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Background: The prevalence of childhood obesity and diabetes continues to rise in the United States (US), especially among minority populations. The objective of the Early Tracking of Childhood Health Determinants (ETCHED) study is to investigate the role of adverse fetal and early-life risk exposures that contribute to the development of childhood obesity and metabolic risk. Methods: ETCHED is a longitudinal observational study of American Indian/Alaska Native (AI/AN) and Hispanic pregnant woman and their offspring. Pregnant mothers ≥ 18 years old are enrolled at a large public hospital system in the southwestern US. Enrolled mothers are followed through pregnancy, delivery, and the maternal/offspring dyad will be followed until the child's 18th birthday. At each maternal visit, questionnaires assessing medical history, diet, physical activity, sleep, perceived stress, and socioeconomic and sociocultural information are obtained. Standard laboratory tests during maternal visits include glycemic measures, lipids, and renal function. Additional bio samples obtained include venous blood samples and cord blood for obesity/metabolic biomarkers and genetic/epigenetic testing, urinalysis, placental tissue for examining functional pathways, breast milk for metabolomics, and stool for metabolites and microbiome analysis. The offspring will have 6 infant/toddler visits at 6–12 weeks, 4 months, 6 months, 18 months, 2 and 3 years respectively. Thereafter, they will undergo comprehensive research visits (major visits) at 4–5 years, 6–9 years, 10–13 years, and 14–17 years. The major visits in children include detailed medical history, anthropometry, developmental assessment, socioeconomic and environmental assessments (food insecurity, family structure, and childcare), feeding and activity, biochemical tests, genetics/epigenetic testing, and ultrasound elastography. Electronic health records will be reviewed for additional clinical information. The primary analysis will constitute estimation of correlation coefficients between continuous variables. The planned study duration in this ongoing study is 23-years. Discussion: This is a life course study that that will examine biological and environmental risk factors for obesity and cardiometabolic risk from the intrauterine period to early childhood and adolescence in a population with high-risk of obesity and type 2 diabetes in the United States. The ETCHED study would also provide a unique opportunity to combine multi-omics and clinical data to create novel integrative models to predict the cardiometabolic risk associated with childhood obesity and possibly identify etiopathogenetic mechanisms and future targets of intervention. Trial registration number: ClinicalTrials.gov identifier: NCT03481829. Updated July 19, 2024, https://clinicaltrials.gov/study/NCT03481829?cond=ETCHED&rank=1. [ABSTRACT FROM AUTHOR]

Objective: Rare cases of monogenic obesity, which may respond to specific therapeutics, can remain undetected in populations in which polygenic obesity is prevalent. This study examined rare DNA variation in established monogenic obesity genes within a community using whole‐exome sequence data from 6803 longitudinally studied individuals. Methods: Exome data across 15 monogenic obesity genes were analyzed for nonsynonymous variants observed in any child with a maximum BMI z score > 2 (N = 279) but not observed in a child with a maximum BMI z score ≤ 0 (n = 1542) or that occurred in adults in the top 5th percentile of BMI (n = 263) but not in adults below the median BMI (n = 2629). Variants were then functionally analyzed using luciferase assays. Results: The comparisons between cases of obesity and controls identified eight missense variants in six genes: DYRK1B, KSR2, MC4R, NTRK2, PCSK1, and SIM1. Among these, MC4R p.A303P and p.R165G were previously shown to impair MC4R function. Functional analyses of the remaining six variants suggest that KSR2 p.I402F and p.T193I and NTRK2 p.S249Y alter protein function. Conclusions: In addition to MC4R, rare missense variants in KSR2 and NTRK2 may potentially explain the severe obesity observed for the carriers. [ABSTRACT FROM AUTHOR]

Genetic determinants of interindividual differences in energy expenditure (EE) are largely unknown. Sphingolipids, such as ceramides, have been implicated in the regulation of human EE via mitochondrial uncoupling. In this study, we investigated whether genetic variants within enzymes involved in sphingolipid synthesis and degradation affect EE and insulin-related traits in a cohort of American Indians informative for 24-h EE and glucose disposal rates during a hyperinsulinemic-euglycemic clamp. Association analysis of 10,084 genetic variants within 28 genes involved in sphingolipid pathways identified a missense variant (rs267738, A>C, E115A) in exon 4 of CERS2 that was associated with higher sleeping EE (116 kcal/day) and increased rates of endogenous glucose production during basal (5%) and insulin-stimulated (43%) conditions, both indicators of hepatic insulin resistance. The rs267738 variant did not affect ceramide synthesis in HepG2 cells but resulted in a 30% decrease in basal mitochondrial respiration. In conclusion, we provide evidence that the CERS2 rs267738 missense variant may influence hepatic glucose production and postabsorptive sleeping metabolic rate. Article Highlights: The genetic determinants of interindividual differences in energy expenditure (EE) are not well established. Sphingolipids have been proposed to influence EE by altering mitochondrial function. Association analysis of genetic variants in genes involved in sphingolipid pathways identified a missense variant (rs267738, A>C, E115A) in CERS2 associated with higher sleeping EE assessed by whole-room indirect calorimetry. The rs267738 variant was associated with increased glucose production under basal and insulin-stimulated conditions and with decreased basal mitochondrial respiration. The rs267738 missense variant may affect the expression of key gluconeogenic genes G6PC1 and PCK1. [ABSTRACT FROM AUTHOR]

We sought to identify genetic/immunologic contributors of type 2 diabetes (T2D) in an indigenous American community by genotyping all study participants for both high-resolution HLA-DRB1 alleles and SLC16A11 to test their risk and/or protection for T2D. These genes were selected based on independent reports that HLA-DRB1*16:02:01 is protective for T2D and that SLC16A11 associates with T2D in individuals with BMI <35 kg/m2. Here, we test the interaction of the two loci with a more complete data set and perform a BMI sensitivity test. We defined the risk protection haplotype of SLC16A11 , T-C-G-T-T , as allele 2 of a diallelic genetic model with three genotypes, SLC16A11*11 , *12 , and *22 , where allele 1 is the wild type. Both earlier findings were confirmed. Together in the same logistic model with BMI ≥35 kg/m2, DRB1*16:02:01 remains protective (odds ratio [OR] 0.73), while SLC16A11 switches from risk to protection (OR 0.57 [ *22 ] and 0.78 [ *12 ]); an added interaction term was statistically significant (OR 0.49 [ *12 ]). Bootstrapped (b = 10,000) statistical power of interaction, 0.4801, yielded a mean OR of 0.43. Sensitivity analysis demonstrated that the interaction is significant in the BMI range of 30–41 kg/m2. To investigate the epistasis, we used the primary function of the HLA-DRB1 molecule, peptide binding and presentation, to search the entire array of 15-mer peptides for both the wild-type and ancient human SLC16A11 molecules for a pattern of strong binding that was associated with risk and protection for T2D. Applying computer binding algorithms suggested that the core peptide at SLC16A11 D127G, FSAFASGLL, might be key for moderating risk for T2D with potential implications for type 1 diabetes. Article Highlights: This study enlarged our sample of high-resolution HLA-DRB1 alleles and 5 individually typed mutations for the SLC16A11 locus and used these to test for protection, risk, and interaction for type 2 diabetes. We confirmed our earlier reports of protection (DRB1*16:02) and risk (SLC16A11) and used all genotypes in a sensitivity analysis for BMI. HLA-DRB1*16:02 was found to be protective, and sensitivity analysis demonstrated that SLC16A11 is a risk in lower BMI strata and protective in higher ones. Epistasis for individuals with DRB1*16:02 and T-C-G-T-T reduces the odds for type 2 diabetes in a BMI range of 30–41 kg/m2, and binding studies implicate core peptide FSAFASGLL. [ABSTRACT FROM AUTHOR]

Aim: Reduced renal insulin signalling is implicated in the pathogenesis of albuminuria. We sought to investigate whether insulin action and secretion, measured before diabetes onset, are associated with the development of albuminuria after diabetes onset. Materials and Methods: Baseline body composition, insulin sensitivity by hyperinsulinaemic‐euglycaemic clamp at submaximal and maximal insulin stimulation (240 and 2400 pmol/m2/min; M‐low and M‐high), and insulin secretion by intravenous glucose tolerance test [acute insulin response (AIR)] were measured in 170 Southwestern Indigenous American adults who subsequently developed diabetes. After diabetes onset and during the median follow‐up of 13.6 years, 81 participants (48%) developed albuminuria (urine albumin‐to‐creatinine ratio ≥30 mg/g). Separate associations of M‐low, M‐high and AIR (per 1‐SD change) with the risk of albuminuria were assessed by Cox regression models adjusted for age, sex and body fat (%). Results: Participants who developed albuminuria were of similar age (26.4 ± 5.4 vs. 27.5 ± 6.1 years), sex (46% vs. 48% male), body fat (36.4 ± 7.5 vs. 35.7 ± 7.9%) and AIR [2.3 ± 0.3 vs. 2.3 ± 0.3, pmol/L (log)] as those who did not develop albuminuria but had lower insulin sensitivity [M‐low: 0.33 ± 0.08 vs. 0.36 ± 0.12, p =.03; M‐high: 0.87 ± 0.11 vs. 0.91 ± 0.12, p =.02; mg/kg‐metabolic body size/min (log)]. In separate adjusted models, lower M‐low and M‐high were both associated with an increased risk for albuminuria [hazard ratio (HR) 1.51, 95% confidence interval (CI) 1.14, 2.00, p =.004; HR 1.31, 95% CI 1.06, 1.63, p =.01), whereas AIR was not (HR 1.15, 95% CI 0.87, 1.56, p =.3). Conclusions: Lower insulin sensitivity is associated with the development of albuminuria, suggesting a role for insulin signalling in the pathogenesis of proteinuria. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To examine the role of glycemic measures performed during childhood in predicting future diabetes-related nephropathy and retinopathy in a high-risk indigenous American cohort. RESEARCH DESIGN AND METHODS: We studied associations between glycated hemoglobin (HbA1c) and 2-h plasma glucose (PG), measured during childhood (age 5 to <20 years) in a longitudinal observational study of diabetes and its complications (1965–2007), and future albuminuria (albumin creatinine ratio [ACR] ≥30 mg/g), severe albuminuria (ACR ≥300 mg/g), and retinopathy (at least one microaneurysm or hemorrhage or proliferative retinopathy on direct ophthalmoscopy). Areas under the receiver operating characteristic curve (AUCs) for childhood glycemic measures when predicting nephropathy and retinopathy were compared. RESULTS: Higher baseline levels of HbA1c and 2-h PG significantly increased the risk of future severe albuminuria (HbA1c: hazard ratio [HR] 1.45 per %; 95% CI 1.02–2.05 and 2-h PG: HR 1.21 per mmol/L; 95% CI 1.16–1.27). When categorized by baseline HbA1c, children with prediabetes had a higher incidence of albuminuria (29.7 cases per 1,000 person-years [PY]), severe albuminuria (3.8 cases per 1,000 PY), and retinopathy (7.1 cases per 1,000 PY) than children with normal HbA1c levels (23.8, 2.4, and 1.7 cases per 1,000 PY, respectively); children with diabetes at baseline had the highest incidence of the three complications. No significant differences were observed between AUCs for models with HbA1c, 2-h PG, and fasting PG when predicting albuminuria, severe albuminuria, or retinopathy. CONCLUSIONS: In this study, higher glycemia levels ascertained by HbA1c and 2-h PG during childhood were associated with future microvascular complications; this demonstrates the potential utility of screening tests performed in high-risk children in predicting long-term health outcomes. [ABSTRACT FROM AUTHOR]

Early puberty onset is associated with higher risk of diabetes, but most studies have not accounted for childhood factors that may confound the association. Using data from a study conducted in an Indigenous community in Arizona (1965–2007), we examined associations of timing and velocity of the adolescent growth spurt with type 2 diabetes, and whether these associations are mediated by childhood body mass index and insulinemia. Adolescent growth parameters were derived from the Preece-Baines growth model, a parametric growth curve fitted to longitudinal height data, for 861 participants with height measurements spanning the whole period of growth. In males, older age at take-off, age at peak velocity, and age at maturation were associated with decreased prevalence of diabetes (odds ratio (OR) = 0.43 per year, 95% confidence interval (CI): 0.27, 0.69; OR = 0.50, 95% CI: 0.35, 0.72; OR = 0.58, 95% CI: 0.41, 0.83, respectively), while higher velocity at take-off was associated with increased risk (OR = 3.47 per cm/year, 95% CI: 1.87, 6.42) adjusting for age, birth year, and maternal diabetes. Similar results were observed with incident diabetes. Our findings suggest that an early and accelerated adolescent growth spurt is a risk factor for diabetes, at least in males. These associations are only partially explained by measures of adiposity and insulinemia. [ABSTRACT FROM AUTHOR]

Genome-wide significant loci for metformin response in type 2 diabetes reported elsewhere have not been replicated in the Diabetes Prevention Program (DPP). To assess pharmacogenetic interactions in prediabetes, we conducted a genome-wide association study (GWAS) in the DPP. Cox proportional hazards models tested associations with diabetes incidence in the metformin (MET; n = 876) and placebo (PBO; n = 887) arms. Multiple linear regression assessed association with 1-year change in metformin-related quantitative traits, adjusted for baseline trait, age, sex, and 10 ancestry principal components. We tested for gene-by-treatment interaction. No significant associations emerged for diabetes incidence. We identified four genome-wide significant variants after correcting for correlated traits (P < 9 × 10−9). In the MET arm, rs144322333 near ENOSF1 (minor allele frequency [MAF]AFR = 0.07; MAFEUR = 0.002) was associated with an increase in percentage of glycated hemoglobin (per minor allele, β = 0.39 [95% CI 0.28, 0.50]; P = 2.8 × 10−12). rs145591055 near OMSR (MAF = 0.10 in American Indians) was associated with weight loss (kilograms) (per G allele, β = −7.55 [95% CI −9.88, −5.22]; P = 3.2 × 10−10) in the MET arm. Neither variant was significant in PBO; gene-by-treatment interaction was significant for both variants [P(G×T) < 1.0 × 10−4]. Replication in individuals with diabetes did not yield significant findings. A GWAS for metformin response in prediabetes revealed novel ethnic-specific associations that require further investigation but may have implications for tailored therapy. [ABSTRACT FROM AUTHOR]

Epigenetic markers are potential biomarkers for diabetes and related complications. Using a prospective cohort from the Hong Kong Diabetes Register, we perform two independent epigenome-wide association studies to identify methylation markers associated with baseline estimated glomerular filtration rate (eGFR) and subsequent decline in kidney function (eGFR slope), respectively, in 1,271 type 2 diabetes subjects. Here we show 40 (30 previously unidentified) and eight (all previously unidentified) CpG sites individually reach epigenome-wide significance for baseline eGFR and eGFR slope, respectively. We also develop a multisite analysis method, which selects 64 and 37 CpG sites for baseline eGFR and eGFR slope, respectively. These models are validated in an independent cohort of Native Americans with type 2 diabetes. Our identified CpG sites are near genes enriched for functional roles in kidney diseases, and some show association with renal damage. This study highlights the potential of methylation markers in risk stratification of kidney disease among type 2 diabetes individuals. Epigenetic markers are potential biomarkers for diabetes and related complications. Here, the authors identify CpG sites associated with kidney function and its subsequent decline using both single-site and multisite analyses, which are shown to have functional significance in the kidney. [ABSTRACT FROM AUTHOR]

Aims/hypothesis: There is limited information on how polygenic scores (PSs), based on variants from genome-wide association studies (GWASs) of type 2 diabetes, add to clinical variables in predicting type 2 diabetes incidence, particularly in non-European-ancestry populations. Methods: For participants in a longitudinal study in an Indigenous population from the Southwestern USA with high type 2 diabetes prevalence, we analysed ten constructions of PS using publicly available GWAS summary statistics. Type 2 diabetes incidence was examined in three cohorts of individuals without diabetes at baseline. The adult cohort, 2333 participants followed from age ≥20 years, had 640 type 2 diabetes cases. The youth cohort included 2229 participants followed from age 5–19 years (228 cases). The birth cohort included 2894 participants followed from birth (438 cases). We assessed contributions of PSs and clinical variables in predicting type 2 diabetes incidence. Results: Of the ten PS constructions, a PS using 293 genome-wide significant variants from a large type 2 diabetes GWAS meta-analysis in European-ancestry populations performed best. In the adult cohort, the AUC of the receiver operating characteristic curve for clinical variables for prediction of incident type 2 diabetes was 0.728; with the PS, 0.735. The PS's HR was 1.27 per SD (p=1.6 × 10−8; 95% CI 1.17, 1.38). In youth, corresponding AUCs were 0.805 and 0.812, with HR 1.49 (p=4.3 × 10−8; 95% CI 1.29, 1.72). In the birth cohort, AUCs were 0.614 and 0.685, with HR 1.48 (p=2.8 × 10−16; 95% CI 1.35, 1.63). To further assess the potential impact of including PS for assessing individual risk, net reclassification improvement (NRI) was calculated: NRI for the PS was 0.270, 0.268 and 0.362 for adult, youth and birth cohorts, respectively. For comparison, NRI for HbA1c was 0.267 and 0.173 for adult and youth cohorts, respectively. In decision curve analyses across all cohorts, the net benefit of including the PS in addition to clinical variables was most pronounced at moderately stringent threshold probability values for instituting a preventive intervention. Conclusions/interpretation: This study demonstrates that a European-derived PS contributes significantly to prediction of type 2 diabetes incidence in addition to information provided by clinical variables in this Indigenous study population. Discriminatory power of the PS was similar to that of other commonly measured clinical variables (e.g. HbA1c). Including type 2 diabetes PS in addition to clinical variables may be clinically beneficial for identifying individuals at higher risk for the disease, especially at younger ages. [ABSTRACT FROM AUTHOR]

Context: Insulin secretion and sensitivity regulate glycemia, with inadequately compensated deficiencies leading to diabetes. Objective: We investigated effects of weight loss, an intensive lifestyle intervention (ILS), and metformin on the relationship between insulin secretion and sensitivity using repository data from 2931 participants in the Diabetes Prevention Program clinical trial in adults at high risk of developing type 2 diabetes. Methods: Insulin secretion and sensitivity were estimated from insulin and glucose concentrations in fasting and 30-minute postload serum samples at baseline and 1, 2, and 3 years after randomization, during the active intervention phase. The nonlinear relationship of secretion and sensitivity was evaluated by standardized major axis regression to account for variability in both variables. Insulin secretory demand and compensatory insulin secretion were characterized by distances along and away from the regression line, respectively. Results: ILS and metformin decreased secretory demand while increasing compensatory insulin secretion, with greater effects of ILS. Improvements were directly related to weight loss; decreased weight significantly reduced secretory demand (b=-0.144 SD; 95% CI (-0.162, -0.125)/5 kg loss) and increased compensatory insulin secretion (b=0.287 SD, 95% CI (0.261, 0.314)/5 kg loss). In time-dependent hazard models, increasing compensatory insulin secretion (hazard ratio [HR]=0.166 per baseline SD, 95% CI 0.133, 0.206) and weight loss (HR=0.710 per 5 kg loss, 95% CI 0.613, 0.819) predicted lower diabetes risk. Conclusion: Diabetes risk reduction was directly related to the amount of weight loss, an effect mediated by lowered insulin secretory demand (due to increased insulin sensitivity) coupled with improved compensatory insulin secretion. [ABSTRACT FROM AUTHOR]

Background Growth abnormalities in childhood have been related to later cardiometabolic risks, but little is known about these associations in populations at high risk of type 2 diabetes. Objectives We examined the associations of patterns of growth, including weight and height at ages 1–59 months, with cardiometabolic risk factors at ages 5–16 years. Methods We linked anthropometric data collected at ages 1–59 months to cardiometabolic data obtained from a longitudinal study in a southwestern American Indian population at high risk of diabetes. Analyses included 701 children with ≥1 follow-up examination at ages 5–16 years. We derived age- and sex-specific weight-for-height z -scores (WHZ) and height-for-age z -scores (HAZ) at ages 1–59 months. We selected the highest observed WHZ and the lowest observed HAZ at ages 1–59 months and analyzed associations of z -scores and categories of WHZ and HAZ with cardiometabolic outcomes at ages 5–16 years. We used linear mixed-effects models to account for repeated measures. Results Overweight/obesity (WHZ >2) at ages 1–59 months was significantly associated with increased BMI, fasting and 2-hour postload plasma glucose, fasting and 2-hour insulin, triglycerides, systolic blood pressure, diastolic blood pressure, and decreased HDL cholesterol at ages 5–16 years relative to normal weight (WHZ ≤1). For example, at ages 5–9 years, 2-hour glucose was 10.4 mg/dL higher (95% CI: 5.6–15.3 mg/dL) and fasting insulin was 4.29 μU/mL higher (95% CI: 2.96–5.71 μU/mL) in those with overweight/obesity in early childhood. Associations were attenuated and no longer significant when adjusted for concurrent BMI. A low height-for-age (HAZ < −2) at ages 1–59 months was associated with 5.37 mg/dL lower HDL (95% CI: 2.57–8.17 mg/dL) and 27.5 μU/mL higher 2-hour insulin (95% CI: 3.41–57.6 μU/mL) at ages 10–16 years relative to an HAZ ≥0. Conclusions In this American Indian population, findings suggest a strong contribution of overweight/obesity in early childhood to cardiometabolic risks in later childhood and adolescence, mediated through persistent overweight/obesity into later ages. Findings also suggest potential adverse effects of low height-for-age, which require confirmation. [ABSTRACT FROM AUTHOR]

Clinical and biomarker phenotypic associations for carriers of protein function-altering variants may help to elucidate gene function and health effects in populations. We genotyped 1127 Strong Heart Family Study participants for protein function-altering single nucleotide variants (SNV) and indels selected from a low coverage whole exome sequencing of American Indians. We tested the association of each SNV/indel with 35 cardiometabolic traits. Among 1206 variants (average minor allele count = 20, range of 1 to 1064), ~ 43% were not present in publicly available repositories. We identified seven SNV-trait significant associations including a missense SNV at ABCA10 (rs779392624, p = 8 × 10–9) associated with fasting triglycerides, which gene product is involved in macrophage lipid homeostasis. Among non-diabetic individuals, missense SNVs at four genes were associated with fasting insulin adjusted for BMI (PHIL, chr6:79,650,711, p = 2.1 × 10–6; TRPM3, rs760461668, p = 5 × 10–8; SPTY2D1, rs756851199, p = 1.6 × 10–8; and TSPO, rs566547284, p = 2.4 × 10–6). PHIL encoded protein is involved in pancreatic β-cell proliferation and survival, and TRPM3 protein mediates calcium signaling in pancreatic β-cells in response to glucose. A genetic risk score combining increasing insulin risk alleles of these four genes was associated with 53% (95% confidence interval 1.09, 2.15) increased odds of incident diabetes and 83% (95% confidence interval 1.35, 2.48) increased odds of impaired fasting glucose at follow-up. Our study uncovered novel gene-trait associations through the study of protein-coding variants and demonstrates the advantages of association screenings targeting diverse and high-risk populations to study variants absent in publicly available repositories. [ABSTRACT FROM AUTHOR]

Aims: Hormone sensitive lipase (HSL), encoded by the LIPE gene, is involved in lipolysis. Based on prior animal and human studies, LIPE was analysed as a candidate gene for the development of type 2 diabetes (T2D) in a community‐based sample of American Indians. Materials and methods: Whole‐exome sequence data from 6782 participants with longitudinal clinical measures were used to identify variation in LIPE. Results: Amongst the 16 missense variants identified, an Arg611Cys variant (rs34052647; Cys‐allele frequency = 0.087) significantly associated with T2D (OR [95% CI] = 1.38 [1.17–1.64], p = 0.0002, adjusted for age, sex, birth year, and the first five genetic principal components) and an earlier onset age of T2D (HR = 1.22 [1.09–1.36], p = 0.0005). This variant was further analysed for quantitative traits related to T2D. Amongst non‐diabetic American Indians, those with the T2D risk Cys‐allele had increased insulin levels during an oral glucose tolerance test (0.07 SD per Cys‐allele, p = 0.04) and a mixed meal test (0.08 log10µU/ml per Cys‐allele, p = 0.003), and had increased lipid oxidation rates post‐absorptively and during insulin infusion (0.07 mg [kg estimated metabolic body size {EMBS}]−1 min−1 per Cys‐allele for both, p = 0.01 and 0.009, respectively), compared to individuals with the non‐risk Arg‐allele. In vitro functional studies showed that cells expressing the Cys‐allele had a 17.2% decrease in lipolysis under isoproterenol stimulation (p = 0.03) and a 21.3% decrease in lipase enzyme activity measured by using p‐nitrophenyl butyrate as a substrate (p = 0.04) compared to the Arg‐allele. Conclusion: The Arg611Cys variant causes a modest impairment in lipolysis, thereby affecting glucose homoeostasis and risk of T2D. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to identify genetic variants enriched in Southwest American Indian (SWAI) individuals that associate with BMI. Methods: Whole genome sequencing data (n = 296) were used to identify potentially functional variants that are common in SWAI individuals (minor allele frequency ≥10%) but rare in other ethnic groups (minor allele frequency < 0.1%). Enriched variants were tested for association with BMI in 5,870 SWAI individuals. One variant was studied using a luciferase reporter, and haplotypes that included this variant were analyzed for association with various measures of obesity (n = 917‐5,870), 24‐hour energy expenditure (24‐h EE; n = 419), and skeletal muscle biopsy expression data (n = 207). Results: A 5′ untranslated region variant in cytochrome b5 type A (CYB5A), rs548402150, met the enrichment criteria and associated with increased BMI (β = 2%, p = 0.004). Functionally, rs548402150 decreased luciferase expression by 30% (p = 0.003) and correlated with decreased skeletal muscle CYB5A expression (β = −0.5 SD, p = 0.0008). Combining rs548402150 with two splicing quantitative trait loci in CYB5A identified a haplotype carried almost exclusively in SWAI individuals that associated with increased BMI (β = 3%, p = 0.0003) and decreased CYB5A expression, whereas the most common haplotype in all ethnic groups associated with lower BMI and percentage of body fatness, increased 24‐h EE, and increased CYB5A expression. Conclusions: Further studies on the effects of CYB5A on 24‐h EE and BMI may provide insights into obesity‐related physiology. [ABSTRACT FROM AUTHOR]

We assessed whether the relationship between insulin secretion and sensitivity predicted development of type 2 diabetes in American Indians participating in a longitudinal epidemiologic study. At baseline, when all participants did not have diabetes, 1,566 underwent oral tests and 420 had intravenous measures of glucose regulation, with estimates of insulin secretion and sensitivity. Standardized major axis regression was used to study the relationship between secretion and sensitivity. Distances away from and along the regression line estimated compensatory insulin secretion and secretory demand, respectively. This relationship differed according to glucose tolerance and BMI category. The distance away from the line is similar to the disposition index (DI), defined as the product of estimated secretion and sensitivity, but the regression line may differ from a line with constant DI (i.e., it is not necessarily hyperbolic). Participants with the same DI but different levels of insulin secretion and sensitivity had different incidence rates of diabetes; lower sensitivity with higher secretory demand was associated with greater diabetes risk. Insulin secretion and insulin sensitivity, analyzed together, predict diabetes better than DI alone. Physiologically, this may reflect long-term risk associated with increased allostatic load resulting from the stimulation of insulin hypersecretion by increased glycemia. [ABSTRACT FROM AUTHOR]

Purpose Of Review: The present review focuses on the epidemiology of type 2 diabetes (T2D) in Indigenous communities in the continental United States (U.S.)-including disease prevention and management-and discusses special considerations in conducting research with Indigenous communities.Recent Findings: Previous studies have reported the disparately high prevalence of diabetes, especially T2D, among Indigenous peoples in the U.S. The high prevalence and incidence of early-onset T2D in Indigenous youth relative to that of all youth in the U.S. population pose challenges to the prevention of complications of diabetes. Behavioral, dietary, lifestyle, and genetic factors associated with T2D in Indigenous communities are often investigated. More limited is the discussion of the historical and ongoing consequences of colonization and displacement that impact the aforementioned risk factors. Future research is necessary to assess community-specific needs with respect to diabetes prevention and management across the diversity of Indigenous communities in the U.S. [ABSTRACT FROM AUTHOR]

Objective: In an ongoing effort to identify the genetic variation that contributes to obesity in American Indians, known Bardet–Biedl syndrome (BBS) genes were analyzed for an effect on BMI and leptin signaling. Methods: Potentially deleterious variants (Combined Annotation Dependent Depletion score > 20) in BBS genes were identified in whole‐exome sequence data from 6,851 American Indians informative for BMI. Common variants (detected in ≥ 10 individuals) were analyzed for association with BMI; rare variants (detected in < 10 individuals) were analyzed for mean BMI of carriers. Functional assessment of variants' effect on signal transducer and activator of transcription 3 (STAT3) activity was performed in vitro. Results: One common variant, rs59252892 (Thr549Ile) in BBS9, was associated with BMI (P = 0.0008, β = 25% increase per risk allele). Among rare variants for which carriers had severe obesity (mean BMI > 40 kg/m2), four were in BBS9. In vitro analysis of BBS9 found the Ile allele at Thr549Ile had a 20% increase in STAT3 activity compared with the Thr allele (P = 0.01). Western blot analysis showed the Ile allele had a 15% increase in STAT3 phosphorylation (P = 0.006). Comparable functional results were observed with Ser545Gly and Val209Leu but not Leu665Phe and Lys810Glu. Conclusions: Potentially functional variants in BBS genes in American Indians are reported. However, functional evidence supporting a causal role for BBS9 in obesity is inconclusive. [ABSTRACT FROM AUTHOR]

Microbial resistance to currently available antibiotics poses a great threat in the global fight against infections. An important step in determining bacterial antibiotic resistance can be selective DNA sequence capture and fluorescence labeling. In this paper, we demonstrate the fabrication of simple, robust, inexpensive microfluidic devices for DNA capture and fluorescence detection of a model antibiotic resistance gene sequence. We laser micromachined polymethyl methacrylate microchannels and enclosed them using pressure-sensitive adhesive tapes. We then formed porous polymer monoliths with DNA capture probes in these microchannels and used them for sequence-specific capture, fluorescent labeling, and laser-induced fluorescence detection of picomolar (pM) concentrations of synthetic and plasmid antibiotic resistance gene targets. The relative fluorescence for the elution peaks increased with loaded target DNA concentration. We observed higher fluorescence signal and percent recovery for synthetic target DNA compared to plasmid DNA at the same loaded target concentration. A non-target gene was used for control experiments and produced < 3% capture relative to the same concentration of target. The full analysis process including device fabrication was completed in less than 90 min with a limit of detection of 30 pM. The simplicity of device fabrication and good DNA capture selectivity demonstrated herein have potential for application with processes for bacterial plasmid DNA extraction and single-particle counting to facilitate determination of antibiotic susceptibility. [ABSTRACT FROM AUTHOR]

Insulin is an essential hormone that regulates glucose homeostasis and metabolism. Insulin resistance (IR) arises when tissues fail to respond to insulin, and it leads to serious health problems including Type 2 Diabetes (T2D). Obesity is a major contributor to the development of IR and T2D. We previously showed that gene expression of alcohol dehydrogenase 1B (ADH1B) was inversely correlated with obesity and IR in subcutaneous adipose tissue of Mexican Americans. In the current study, a meta-analysis of the relationship between ADH1B expression and BMI in Mexican Americans, African Americans, Europeans, and Pima Indians verified that BMI was increased with decreased ADH1B expression. Using established human subcutaneous pre-adipocyte cell lines derived from lean (BMI < 30 kg m−2) or obese (BMI ≥ 30 kg m−2) donors, we found that ADH1B protein expression increased substantially during differentiation, and overexpression of ADH1B inhibited fatty acid binding protein expression. Mature adipocytes from lean donors expressed ADH1B at higher levels than obese donors. Insulin further induced ADH1B protein expression as well as enzyme activity. Knockdown of ADH1B expression decreased insulin-stimulated glucose uptake. Our findings suggest that ADH1B is involved in the proper development and metabolic activity of adipose tissues and this function is suppressed by obesity. [ABSTRACT FROM AUTHOR]

Aims/hypothesis: Prevalence of type 2 diabetes differs among human ancestry groups, and many hypotheses invoke differential natural selection to account for these differences. We sought to assess the potential role of differential natural selection across major continental ancestry groups for diabetes and related traits, by comparison of genetic and phenotypic differences. Methods: This was a cross-sectional comparison among 734 individuals from an urban sample (none of whom was more closely related to another than third-degree relatives), including 83 African Americans, 523 American Indians and 128 European Americans. Participants were not recruited based on diabetes status or other traits. BMI was calculated, and diabetes was diagnosed by a 75 g oral glucose tolerance test. In those with normal glucose tolerance (n = 434), fasting insulin and 30 min post-load insulin, adjusted for 30 min glucose, were taken as measures of insulin resistance and secretion, respectively. Whole exome sequencing was performed, resulting in 97,388 common (minor allele frequency ≥ 5%) variants; the coancestry coefficient (FST) was calculated across all markers as a measure of genetic divergence among ancestry groups. The phenotypic divergence index (PST) was also calculated from the phenotypic differences and heritability (which was estimated from genetic relatedness calculated empirically across all markers in 761 American Indian participants prior to the exclusion of close relatives). Under evolutionary neutrality, the expectation is PST = FST, while for traits under differential selection PST is expected to be significantly greater than FST. A bootstrap procedure was used to test the hypothesis PST = FST. Results: With adjustment for age and sex, prevalence of type 2 diabetes was 34.0% in American Indians, 12.4% in African Americans and 10.4% in European Americans (p = 2.9 × 10−10 for difference among groups). Mean BMI was 36.3, 33.4 and 33.0 kg/m2, respectively (p = 1.9 × 10−7). Mean fasting insulin was 63.8, 48.4 and 45.2 pmol/l (p = 9.2 × 10−5), while mean 30 min insulin was 559.8, 553.5 and 358.8 pmol/l, respectively (p = 5.7 × 10−8). FST across all markers was 0.130, while PST for liability to diabetes, adjusted for age and sex, was 0.149 (p = 0.35 for difference with FST). PST was 0.094 for BMI (p = 0.54), 0.095 for fasting insulin (p = 0.54) and 0.216 (p = 0.18) for 30 min insulin. For type 2 diabetes and BMI, the maximum divergence between populations was observed between American Indians and European Americans (PST-MAX = 0.22, p = 0.37, and PST-MAX = 0.14, p = 0.61), which suggests that a relatively modest 22% or 14% of the genetic variance, respectively, can potentially be explained by differential selection (assuming the absence of neutral drift). Conclusions/interpretation: These analyses suggest that while type 2 diabetes and related traits differ significantly among continental ancestry groups, the differences are consistent with neutral expectations based on heritability and genetic distances. While these analyses do not exclude a modest role for natural selection, they do not support the hypothesis that differential natural selection is necessary to explain the phenotypic differences among these ancestry groups. [ABSTRACT FROM AUTHOR]

Background: Obesity and energy expenditure (EE) are heritable and genetic variants influencing EE may contribute to the development of obesity. We sought to identify genetic variants that affect EE in American Indians, an ethnic group with high prevalence of obesity.Methods: Whole-exome sequencing was performed in 373 healthy Pima Indians informative for 24-hour EE during energy balance. Genetic association analyses of all high-quality exonic variants (≥5 carriers) was performed, and those predicted to be damaging were prioritized.Results: Rs752074397 introduces a premature stop codon (Cys264Ter) in DAO and demonstrated the strongest association for 24-hour EE, where the Ter allele associated with substantially lower 24-hour EE (mean lower by 268 kcal/d) and sleeping EE (by 135 kcal/d). The Ter allele has a frequency = 0.5% in Pima Indians, whereas is extremely rare in most other ethnic groups (frequency < 0.01%). In vitro functional analysis showed reduced protein levels for the truncated form of DAO consistent with increased protein degradation. DAO encodes D-amino acid oxidase, which is involved in dopamine synthesis which might explain its role in modulating EE.Conclusion: Our results indicate that a nonsense mutation in DAO may influence EE in American Indians. Identification of variants that influence energy metabolism may lead to new pathways to treat human obesity.Clinical Trial Registration Number: NCT00340132. [ABSTRACT FROM AUTHOR]

Aims/hypothesis: The aim of this work was to examine the associations of average weight and weight velocity in three growth periods from birth through adolescence with type 2 diabetes incidence. Methods: Child participants were selected from a 43 year longitudinal study of American Indians to represent three growth periods: pre-adolescence (birth to ~8 years); early adolescence (~8 to ~13 years); and late adolescence (~13 to ~18 years). Age-, sex- and height-standardised weight z score mean and weight z score velocity (change/year) were computed for each period. Participants were followed for up to 25 years from the end of each growth period until they developed diabetes. Associations of weight z score mean or weight z score velocity with diabetes incidence were determined with sex-, birth date- and maternal diabetes-adjusted Poisson regression models. Results: Among 2100 participants representing the pre-adolescence growth period, 1558 representing the early adolescence period and 1418 representing the late adolescence period, there were 290, 315 and 380 incident diabetes cases, respectively. During the first 10 years of follow-up, the diabetes incidence rate ratio (95% CI) was 1.72 (1.40, 2.11)/SD of log10 weight z score mean in pre-adolescence, 2.09 (1.68, 2.60)/SD of log10 weight z score mean in early adolescence and 1.85 (1.58, 2.17)/SD of log10 weight z score mean in late adolescence. The diabetes incidence rate ratio (95% CI) was 1.79 (1.49, 2.17)/SD of log10 weight z score velocity in pre-adolescence, 1.13 (0.91, 1.41)/SD of log10 weight z score velocity in early adolescence and 1.29 (1.09, 1.51)/SD of log10 weight z score velocity in late adolescence. There were strong correlations in the weight z score means and weak correlations in the weight z score velocities between successive periods. Conclusions/interpretation: Higher weight and accelerated weight gain in all growth periods associate with increased type 2 diabetes risk. Importantly, higher weight and greater weight velocity during pre-adolescence jointly associate with the highest type 2 diabetes risk. [ABSTRACT FROM AUTHOR]

Objective: Insulinlike growth factor II (IGF-II) regulates metabolism and growth. In humans, both positive and negative relationships have been reported between serum IGF-II levels and obesity. This study assessed the relationship between serum IGF-II levels and BMI and determined whether IGF-II levels predict weight gain.Methods: Serum samples were available from 911 American Indians with a recorded BMI. IGF-II was measured using enzyme-linked immunosorbent assay.Results: Serum IGF-II levels were negatively correlated with BMI (r = -0.17, P = 4.4 × 10-7 , adjusted for age, sex, and storage time). The strongest correlation was in participants aged ≥ 30 years (r = -0.28, P = 3.4 × 10-8 , N = 349), a modest correlation was in participants aged 20 to 29 years (r = -0.15, P = 7.6 × 10-3 , N = 322), and participants aged 15 to 19 years had no correlation (r = 0.05, P = 0.48, N = 240). IGF-II levels did not predict weight gain. However, among individuals who had genotypes for 64 established obesity variants (age ≥ 20 years, N = 671), a genetic risk score for high BMI was associated with lower IGF-II (β = -0.08 SD of IGF-II per SD of the genetic risk score, P = 0.025).Conclusions: There is a negative relationship between IGF-II levels and BMI, in which the correlation is stronger at older ages. The association between genetic risk for BMI and IGF-II levels suggests that this correlation may be due to an effect of obesity on IGF-II. [ABSTRACT FROM AUTHOR]

Type 2 diabetes is a common disease worldwide, but its prevalence varies widely by geographical region and by race/ethnicity. This review summarises differences in the frequencies of type 2 diabetes according to race, ethnicity, socioeconomic position, area of residence and environmental toxins. Type 2 diabetes susceptibility often begins early in life, starting with genetic susceptibility at conception and continuing in later life, via in utero, childhood and adult exposures. Early-life factors may lead to overt type 2 diabetes in childhood or in later life, supporting the concept of developmental origins of health and disease. The causes of the racial/ethnic differences in incidence of type 2 diabetes are not well understood. Specifically, the relative contributions of genetic and environmental factors to such differences are largely unknown. With a few exceptions in isolated populations, there is little evidence that differences in frequencies of known type 2 diabetes susceptibility genetic alleles account for racial/ethnic differences, although the search for genetic susceptibility has not been uniform among the world's racial/ethnic groups. In the USA, race/ethnicity is associated with many other risk factors for type 2 diabetes, including being overweight/obese, diet and socioeconomic status. Some studies suggest that some of these factors may account for the race/ethnic differences in prevalence of type 2 diabetes, although there is inadequate research in this area. A better understanding of the impact of these factors on type 2 diabetes risk should lead to more effective prevention and treatment of this disease. This has not yet been achieved but should be a goal for future research. [ABSTRACT FROM AUTHOR]

Aims/hypothesis: Variants in CREBRF (rs12513649 and rs373863828) have been strongly associated with increased BMI and decreased risk of type 2 diabetes in Polynesian populations; the A allele at rs373863828 is common in Polynesians but rare in most other global populations. The aim of the present study was to assess the association of CREBRF variants with obesity and diabetes in Pacific Islander (largely Marianas and Micronesian) populations from Guam and Saipan. Methods: CREBRF rs12513649 and rs373863828 were genotyped in 2022 participants in a community-based cross-sectional study designed to identify determinants of diabetes and end-stage renal disease (ESRD). Associations were analysed with adjustment for age, sex, ESRD and the first four genetic principal components from a genome-wide association study (to account for population stratification); a genomic control procedure was used to account for residual stratification. Results: The G allele at rs12513649 had an overall frequency of 7.7%, which varied from 2.2% to 20.7% across different Marianas and Micronesian populations; overall frequency of the A allele at rs373863828 was 4.2% (range: 1.1–5.4%). The G allele at rs12513649 was associated with higher BMI (β = 1.55 kg/m2 per copy; p = 0.0026) as was the A allele at rs373863828 (β = 1.48 kg/m2, p = 0.033). The same alleles were associated with lower risk of diabetes (OR per copy: 0.63 [p = 0.0063] and 0.49 [p = 0.0022], respectively). Meta-analyses combining the current results with previous results in Polynesians showed a strong association between the A allele at rs373863828 and BMI (β = 1.38 kg/m2; p = 2.5 × 10−29) and diabetes (OR 0.65, p = 1.5 × 10−13). Conclusions/interpretation: These results confirm the associations of CREBRF variants with higher BMI and lower risk of diabetes and, importantly, they suggest that these variants contribute to the risk of obesity and diabetes in Oceanic populations. [ABSTRACT FROM AUTHOR]

Aims/hypothesis: The aim of this work was to estimate the impact of birthweight on early-onset (age <40 years) type 2 diabetes. Methods: A longitudinal study of American Indians, aged ≥5 years, was conducted from 1965 to 2007. Participants who had a recorded birthweight were followed until they developed diabetes or their last examination before the age of 40 years, whichever came first. Age- and sex-adjusted diabetes incidence rates were computed and Poisson regression was used to model the effect of birthweight on diabetes incidence, adjusted for sex, BMI, a type 2 diabetes susceptibility genetic risk score (GRS) and maternal covariates. Results: Among 3039 participants, there were 652 incident diabetes cases over a median follow-up of 14.3 years. Diabetes incidence increased with age and was greater in the lowest and highest quintiles of birthweight. Adjusted for covariates, the effect of birthweight on diabetes varied over time, with a non-linear effect at 10–19 years (p < 0.001) and a negative linear effect at older age intervals (20–29 years, p < 0.001; 30–39 years, p = 0.003). Higher GRS, greater BMI and maternal diabetes had additive but not interactive effects on the association between birthweight and diabetes incidence. Conclusions/interpretation: In this high-risk population, both low and high birthweights were associated with increased type 2 diabetes risk in adolescence (age 10–19 years) but only low birthweight was associated with increased risk in young adulthood (20–39 years). Higher type 2 diabetes GRS, greater BMI and maternal diabetes added to the risk of early-onset diabetes. [ABSTRACT FROM AUTHOR]

Objective: Meta-analyses of genome-wide association studies in Europeans have identified > 98 loci for BMI. Transferability of these established associations in Pima Indians was analyzed.Methods: Among 98 lead single nucleotide polymorphisms (SNPs), 82 had minor allele frequency ≥ 0.01 in Pima Indians and were analyzed for association with the maximum BMI in adulthood (n = 3,491) and BMI z score in childhood (n = 1,958). Common tag SNPs across 98 loci were also analyzed for additional signals.Results: Among the lead SNPs, 13 (TMEM18, TCF7L2, MRPS33P4, PRKD1, ZFP64, FTO, TAL1, CALCR, GNPDA2, CREB1, LMX1B, ADCY9, NLRC3) were associated with BMI (P  ≤ 0.05) in Pima adults. A multi-allelic genetic risk score (GRS), which summed the risk alleles for 82 lead SNPs, showed a significant trend for a positive relationship between GRS and BMI in adulthood (beta = 0.48% per risk allele; P = 1.6 × 10-9 ) and BMI z score in childhood (beta = 0.024 SD; P = 1.7 × 10-7 ). GRS was significantly associated with BMI across all age groups ≥ 5 years, except for those ≥ 50 years. The strongest association was seen in adolescence (age 14-16 years; P = 1.84 × 10-9 ).Conclusions: In aggregate, European-derived lead SNPs had a notable effect on BMI in Pima Indians. Polygenic obesity in this population manifests strongly in childhood and adolescence and persists throughout much of adult life. [ABSTRACT FROM AUTHOR]

Abstract: Prevalence of diabetes and obesity in Mexican Pima Indians is low, while prevalence in US Pima Indians is high. Although lifestyle likely accounts for much of the difference, the role of genetic factors is not well explored. To examine this, we genotyped 359 single nucleotide polymorphisms, including established type 2 diabetes and obesity variants from genome‐wide association studies (GWAS) and 96 random markers, in 342 Mexican Pimas. A multimarker risk score of obesity variants was associated with body mass index (BMI; β = 0.81 kg/m2 per SD, P = 0.0066). The mean value of the score was lower in Mexican Pimas than in US Pimas (P = 4.3 × 10−11), and differences in allele frequencies at established loci could account for approximately 7% of the population difference in BMI; however, the difference in risk scores was consistent with evolutionary neutrality given genetic distance. To identify loci potentially under recent natural selection, allele frequencies at 283 variants were compared between US and Mexican Pimas, accounting for genetic distance. The largest differences were seen at HLA markers (e.g., rs9271720, difference = 0.75, P = 8.7 × 10–9); genetic distances at HLA were greater than at random markers (P = 1.6 × 10–46). Analyses of GWAS data in 937 US Pimas also showed sharing of alleles identical by descent at HLA that exceeds its genomic expectation (P = 7.0 × 10–10). These results suggest that, in addition to the widely recognized balancing selection at HLA, recent directional selection may also occur, resulting in marked allelic differentiation between closely related populations. [ABSTRACT FROM AUTHOR]

Objectives: The risk of early‐onset type 2 diabetes associated with the severity of obesity in youth is not well understood. This study aims to determine metabolic alterations and type 2 diabetes risk among American Indian children who are obese or severely obese. Methods: Incidence rates of diabetes before 20 years (youth‐onset) and 45 years were computed in 2728 children who were from 5 to <10 years and 4317 adolescents who were from 10 to <18 years without diabetes examined between 1965 and 2007. Obesity was defined as age‐sex‐adjusted body mass index (BMI) ≥95th percentile, and its severity was quantified as the percentage of the 95th percentile (%BMIp95). Results: In the younger cohort, 0.9% of those non‐obese and 2.9% of those with 100% to <120%BMIp95 had impaired glucose tolerance (IGT) compared to 8.6% of those with ≥140%BMIp95. In the older cohort, 2.9% of those non‐obese and 9.8% of those with 100% to <120%BMIp95 had IGT compared to 13.3% of those with ≥160%BMIp95. The incidence of youth‐onset diabetes was 3.8 and 4.9/1000 person‐years in the child and adolescent cohorts, respectively, and before the age of 45 was 12.3 and 16.8/1000 person‐years, respectively. Incidence rates of youth‐onset diabetes in those with the most severe obesity (≥140%BMIp95) were 2.3 to 5.1 times as high as in those with the least severe obesity (100 to <120%BMIp95), and for onset of diabetes before the age of 45 were 1.6 to 2.2 times as high. Conclusions: Severe obesity in an American Indian population is a major driver of type 2 diabetes developing in adolescents and young adults. [ABSTRACT FROM AUTHOR]

Background. Inflammation linked to diabetic kidney disease (DKD) may affect white blood cell (WBC) counts and differentials. We examined the cross-sectional associations of total WBC count and WBC fractions with structural lesions of DKD in 108 Pima Indians with Type 2 diabetes who underwent research kidney biopsies. We also examined the longitudinal association of these WBC variables with renal function loss (RFL) in 941 Europeans with Type 2 diabetes from the SURDIAGENE study. Methods. Associations of WBC variables with morphometric parameters were assessed by linear regression. RFL was defined as ⩾40% loss of estimated glomerular filtration rate from baseline. Associations with RFL were evaluated by Cox regression. Hazard ratios (HRs) were reported per standard deviation increment of eachWBC variable. Results. After multivariable adjustment, lymphocyte (r =-0.20, P=0.043) and eosinophil (r=0.21, P=0.032) fractions in the Pima Indians correlated with glomerular basement membrane width. Eosinophil fraction also correlated with glomerular filtration surface density (r =-0.21, P=0.031). Lymphocyte fraction (r=0.25, P=0.013), neutrophil fraction (r =-0.23, P=0.021) and the neutrophil:lymphocyte ratio (r =-0.22, P=0.024) correlated with percentage of normally fenestrated endothelial cells. During median follow-up of 4.5 years, 321 SURDIAGENE participants developed RFL. Lower lymphocyte fraction [HR=0.67, 95% confidence interval (95% CI) 0.60-0.76] and higher neutrophil fraction (HR=1.35, 95% CI 1.20-1.52), total WBC count (HR=1.20, 95% CI 1.08-1.35) and neutrophil:lymphocyte ratio (HR=1.44, 95% CI 1.28-1.62) each predicted RFL in this cohort. Conclusions. WBC fractions associate with morphometric lesions of DKD and predict RFL in individuals with Type 2 diabetes. [ABSTRACT FROM AUTHOR]

Aims: Insulin-like growth factor 1 receptor (IGF1R) is involved in cell growth and glucose homeostasis. In the current study, the IGF1R locus was analysed as a candidate gene for type 2 diabetes (T2D) in American Indians.Materials and Methods: Whole genome sequence data from 335 American Indians identified 3 novel missense variants in IGF1R. The associations of IGF1R variants with T2D, age of T2D onset and birth weight were analysed in a population-based sample of 7701 American Indians.Results: A novel glycine-to-aspartic acid substitution (G310D) in IGF1R was identified, which associated with T2D in a sex-specific manner (Psex interaction = 0.02). In women, the aspartic acid (D) allele (frequency = 0.034) was associated with increased risk for T2D (n = 4292, P = 2.0 × 10-5 adjusted for age, birth year, and the first 5 genetic principal components; odds ratio [OR] = 2.23 [1.54-3.23] per risk allele) and an earlier age of T2D onset (n = 4292, P = 2 × 10-4 , hazard rate ratio = 1.45 [1.20-1.75], Psex interaction = 0.05). Female carriers of the D-allele also had lower birth weight (n = 1313, β = -163 g, P = .006, Psex interaction = 0.008). Among 85 siblings discordant for G310D, carriers of the D-allele had shorter stature as compared with carriers of the G-allele (β = -1.6 cm, P = .001, within family model). The G310D variant was functionally studied in vitro, where the D-allele had a 22% increase (P = .0005) in FOXO1-induced transcriptional activity, due to decreased activation of the PI3K/AKT pathway mediated through reduced IGF1R activity.Conclusion: A unique G310D variant in IGF1R, which occurs in 6% American Indians, may impair IGF1R signalling pathways, thereby increasing the risk of T2D. [ABSTRACT FROM AUTHOR]

Type 2 diabetes (T2D) affects more than 415 million people worldwide, and its costs to the health care system continue to rise. To identify common or rare genetic variation with potential therapeutic implications for T2D, we analyzed and replicated genome-wide protein coding variation in a total of 8,227 individuals with T2D and 12,966 individuals without T2D of Latino descent. We identified a novel genetic variant in the IGF2 gene associated with ∼20% reduced risk for T2D. This variant, which has an allele frequency of 17% in the Mexican population but is rare in Europe, prevents splicing between IGF2 exons 1 and 2. We show in vitro and in human liver and adipose tissue that the variant is associated with a specific, allele-dosage-dependent reduction in the expression of IGF2 isoform 2. In individuals who do not carry the protective allele, expression of IGF2 isoform 2 in adipose is positively correlated with both incidence of T2D and increased plasma glycated hemoglobin in individuals without T2D, providing support that the protective effects are mediated by reductions in IGF2 isoform 2. Broad phenotypic examination of carriers of the protective variant revealed no association with other disease states or impaired reproductive health. These findings suggest that reducing IGF2 isoform 2 expression in relevant tissues has potential as a new therapeutic strategy for T2D, even beyond the Latin American population, with no major adverse effects on health or reproduction. [ABSTRACT FROM AUTHOR]

Background: The adaptive immune system is involved in type 2 diabetes mellitus (T2DM), indicating the presence of unidentified autoantibodies that might be useful biomarkers for emerging immunomodulatory therapy. A prior microarray study with a small number of participants suggested the association of novel autoantibodies with T2DM in Southwest American Indians. We therefore sought to determine whether antibodies against 14 target proteins are associated with T2DM in a large case-control study.Methods: Participants were adults (age 20-59 y) of Southwest American Indian heritage. Plasma antibodies against 14 possible target proteins were measured in 476 cases with T2DM of less than 5 years duration and compared with 424 controls with normal glucose regulation.Results: Higher levels of antibodies against prefoldin subunit 2 (PFDN2) were associated with T2DM (P = .0001; Bonferroni-corrected threshold for multiple tests = 0.0036 [α = 0.05]). The association between anti-PFDN2 antibodies and T2DM remained in multivariable logistic regression (odds ratio 1.27; 95% confidence interval, 1.09-1.49; per one SD difference in anti-PFDN2 antibody). The odds of T2DM were increased in the highest anti-PFDN2 antibody quintile by 66% compared with the lowest quintile. Differences in anti-PFDN2 antibodies were most prominent among cases with earlier onset of disease (ie, age 20-39 y) compared with controls.Conclusions: Anti-PFDN2 antibodies are associated with T2DM and might be a useful biomarker. These findings indicate that autoimmunity may play a role in T2DM in Southwest American Indians, especially among adults presenting with young onset of disease. [ABSTRACT FROM AUTHOR]

Pima Indians living in Arizona have a high prevalence of obesity, and we have previously shown that a relatively lower energy expenditure (EE) predicts weight and fat mass gain in this population. EE is a familial trait (heritability = 0.52); therefore, in the current study, we aimed to identify genetic variants that affect EE and thereby influence BMI and body fatness in Pima Indians. Genotypic data from 491,265 variants were analyzed for association with resting metabolic rate (RMR) and 24-h EE assessed in a whole-room calorimeter in 507 and 419 Pima Indians, respectively. Variants associated with both measures of EE were analyzed for association with maximum BMI and percent body fat (PFAT) in 5,870 and 912 Pima Indians, respectively. rs11014566 nominally associated with both measures of EE and both measures of adiposity in Pima Indians, where the G allele (frequency: Pima Indians = 0.60, Europeans <0.01) associated with lower 24-h EE (β = -33 kcal/day per copy), lower RMR (β = -31 kcal/day), higher BMI (β = +0.6 kg/m2), and higher PFAT (β = +0.9%). However, the association of rs11014566 with BMI did not directionally replicate when assessed in other ethnic groups. rs11014566 tags rs144895904, which affected promoter function in an in vitro luciferase assay. These variants map to GPR158, which is highly expressed in the brain and interacts with two other genes (RGS7 and CACNA1B) known to affect obesity in knockout mice. Our results suggest that common ethnic-specific variation in GPR158 may influence EE; however, its role in weight gain remains controversial, as it either had no association with BMI or associated with BMI but in the opposite direction in other ethnic groups. [ABSTRACT FROM AUTHOR]

Objective: Relationships were examined between persistent organic pollutants (POPs) and incident type 2 diabetes, end-stage renal disease (ESRD) and mortality.Methods: In a nested case-control study, 300 persons without diabetes had baseline examinations between 1969 and 1974; 149 developed diabetes (cases) and 151 remained non-diabetic (controls) during 8.0 and 23.1 years of follow-up, respectively. POPs were measured at baseline. ORs for diabetes were computed by logistic regression analysis. The cases were followed from diabetes onset to ESRD, death or 2013. HRs for ESRD and mortality were computed by cause-specific hazard models. Patterns of association were explored using principal components analysis.Results: PCB151 increased the odds for incident diabetes, whereas hexachlorobenzene (HCB) was protective after adjusting for age, sex, body mass index, sample storage characteristics, glucose and lipid levels. Associations between incident diabetes and polychlorinatedbiphenyl (PCB) or persistent pesticide (PST) components were mostly positive but non-significant. Among the cases, 29 developed ESRD and 48 died without ESRD. PCB28, PCB49 and PCB44 increased the risk of ESRD after adjusting for baseline demographic and clinical characteristics. Several PCBs and PSTs increased the risk of death without ESRD. The principal components analysis identified PCBs with low-chlorine load positively associated with ESRD and death without ESRD, and several PSTs associated with death without ESRD.Conclusions: Most POPs were positively but not significantly associated with incident diabetes. PCB151 was significantly predictive and HCB was significantly protective for diabetes. Among participants with diabetes, low-chlorine PCBs increase the risk of ESRD and death without ESRD, whereas several PSTs predict death without ESRD. [ABSTRACT FROM AUTHOR]

Background: Eight new loci for type 2 diabetes mellitus (T2DM) were identified in an East Asian genome-wide association study meta-analysis. We assess tag SNPs across these loci for associations with T2DM in American Indians.Methods: A total of 435 SNPs that tag (R2  ≥ .85) common variation across the 8 loci were analyzed for association with T2DM (n = 7710), early onset T2DM (n = 1060), body mass index (n = 6839), insulin sensitivity (n = 555), and insulin secretion (n = 298).Results: Tag SNPs within FITM2-R3HDML-HNF4A, GLIS3, KCNK16, and ZFAND3 associated with T2DM after accounting for locus-wide multiple testing. The T2DM association in FITM2-R3HDML-HNF4A (rs3212183; P = .0002; OR = 1.19 [1.09-1.30]) was independent from the East Asian lead SNP (rs6017317), which did not associate with T2DM in American Indians. The top signals in GLIS3 (rs7875253; P = .0004; OR = 1.23 [1.10-1.38]) and KCNK16 (rs1544050; P = .002; OR = 1.16 [1.06-1.27]) were attenuated after adjustment for the East Asian lead SNPs (rs7041847 in GLIS3; rs1535500 in KCNK16), both of which also associated with T2DM in American Indians (P = .02; OR = 1.11 [1.01-1.21]; P = .007; OR = 1.19 [1.05-1.36] respectively). The top SNP in ZFAND3 (rs9470794; P = .002; OR = 1.43 [1.14-1.80]) was the identical East Asian lead SNP. Additional SNPs in GLIS3 (rs180867004) and ZFAND3 (rs4714120 and rs9470701) had significant genotype × sex interactions (P ≤ .008). The GLIS3 SNP (rs180867004) associated with T2DM only in men (P = .00006, OR = 1.94 [1.40-2.68]). The ZFAND3 SNPs (rs4714120 and rs9470701) associated with T2DM only in women (P = .0002, OR = 1.35 [1.16-1.59]; P = .0003, OR = 1.37 [1.16-1.63] respectively).Conclusions: Replication of lead T2DM SNPs in GLIS3, KCNK16, and ZFAND3 was observed in American Indians. Sex-specific T2DM signals in GLIS3 and ZFAND3, which are distinct from the East Asian GWAS signals, were also identified. [ABSTRACT FROM AUTHOR]

Objective: Long-term data validating glycated hemoglobin (HbA1c) in assessing the risk of type 2 diabetes in children are limited. HbA1c, fasting plasma glucose (FPG), and 2-h postload plasma glucose (2hPG) concentrations were measured in a longitudinal study of American Indians to determine their utility in predicting incident diabetes, all of which is thought to be type 2 in this population.Research Design and Methods: Incident diabetes (FPG ≥126 mg/dL [7.0 mmol/L], 2hPG ≥200 mg/dL [11.1 mmol/L], HbA1c ≥6.5% [8 mmol/mol], or clinical diagnosis) was determined in 2,095 children without diabetes ages 10-19 years monitored through age 39, and in 2,005 adults ages 20-39 monitored through age 59. Areas under the receiver operating characteristic (ROC) curve for HbA1c, FPG, and 2hPG in predicting diabetes within 10 years were compared.Results: During long-term follow-up of children and adolescents who did not initially have diabetes, the incidence rate of subsequent diabetes was fourfold (in boys) as high and more than sevenfold (in girls) as high in those with HbA1c ≥5.7% as in those with HbA1c ≤5.3%-greater rate ratios than experienced by adults in the same HbA1c categories. Analyses of ROCs revealed no significant differences between HbA1c, FPG, and 2hPG in sensitivity and specificity for identifying children and adolescents who later developed diabetes.Conclusions: HbA1c is a useful predictor of diabetes risk in children and can be used to identify prediabetes in children with other type 2 diabetes risk factors with the same predictive value as FPG and 2hPG. [ABSTRACT FROM AUTHOR]

Objective: To determine whether early administration of losartan slows progression of diabetic kidney disease over an extended period.Research Design and Methods: We conducted a 6-year clinical trial in 169 American Indians with type 2 diabetes and urine albumin/creatinine ratio <300 mg/g; 84 participants were randomly assigned to receive losartan and 85 to placebo. Primary outcome was a decline in glomerular filtration rate (GFR; iothalamate) to ≤60 mL/min or to half the baseline value in persons who entered with GFR <120 mL/min. At enrollment, GFR averaged 165 mL/min (interquartile range 49-313 mL/min). During the trial, nine persons reached the primary outcome with a hazard ratio (HR; losartan vs. placebo) of 0.50 (95% CI 0.12-1.99). Participants were then followed posttrial for up to 12 years, with treatment managed outside the study. The effect of losartan on the primary GFR outcome was then reanalyzed for the entire study period, including the clinical trial and posttrial follow-up.Results: After completion of the clinical trial, treatment with renin-angiotensin system inhibitors was equivalent in both groups. During a median of 13.5 years following randomization, 29 participants originally assigned to losartan and 35 to placebo reached the primary GFR outcome with an HR of 0.72 (95% CI 0.44-1.18).Conclusions: Long-term risk of GFR decline was not significantly different between persons randomized to early treatment with losartan and those randomized to placebo. Accordingly, we found no evidence of an extended benefit of early losartan treatment on slowing GFR decline in persons with type 2 diabetes. [ABSTRACT FROM AUTHOR]

Genetic variants in SLC16A11 were recently reported to be associated with type 2 diabetes in Mexican and other Latin American populations. The diabetes risk haplotype had a frequency of 50% in Native Americans from Mexico but was rare in Europeans and Africans. In the current study, we analyzed SLC16A11 in 12,811 North American Indians and found that the diabetes risk haplotype, tagged by the rs75493593 A allele, was nominally associated with type 2 diabetes (P = 0.001, odds ratio 1.11). However, there was a strong interaction with BMI (P = 5.1 × 10(-7)) such that the diabetes association was stronger in leaner individuals. rs75493593 was also strongly associated with BMI in individuals with type 2 diabetes (P = 3.4 × 10(-15)) but not in individuals without diabetes (P = 0.77). Longitudinal analyses suggest that this is due, in part, to an association of the A allele with greater weight loss following diabetes onset (P = 0.02). Analyses of global gene expression data from adipose tissue, skeletal muscle, and whole blood provide evidence that rs75493593 is associated with expression of the nearby RNASEK gene, suggesting that RNASEK expression may mediate the effect of genotype on diabetes. [ABSTRACT FROM AUTHOR]

Missense variants in KCNJ11 and ABCC8, which encode the KIR6.2 and SUR1 subunits of the β-cell KATP channel, have previously been implicated in type 2 diabetes, neonatal diabetes, and hyperinsulinemic hypoglycemia of infancy (HHI). To determine whether variation in these genes affects risk for type 2 diabetes or increased birth weight as a consequence of fetal hyperinsulinemia in Pima Indians, missense and common noncoding variants were analyzed in individuals living in the Gila River Indian Community. A R1420H variant in SUR1 (ABCC8) was identified in 3.3% of the population (N = 7,710). R1420H carriers had higher mean birth weights and a twofold increased risk for type 2 diabetes with a 7-year earlier onset age despite being leaner than noncarriers. One individual homozygous for R1420H was identified; retrospective review of his medical records was consistent with HHI and a diagnosis of diabetes at age 3.5 years. In vitro studies showed that the R1420H substitution decreases KATP channel activity. Identification of this loss-of-function variant in ABCC8 with a carrier frequency of 3.3% affects clinical care as homozygous inheritance and potential HHI will occur in 1/3,600 births in this American Indian population. [ABSTRACT FROM AUTHOR]

New biomarkers for type 2 diabetes mellitus (T2DM) may aid diagnosis, drug development or clinical treatment. Evidence is increasing for the adaptive immune system’s role in T2DM and suggests the presence of unidentified autoantibodies. While high-density protein microarrays have emerged as a useful technology to identify possible novel autoantigens in autoimmune diseases, its application in T2DM has lagged. In Pima Indians, the HLA haplotype (HLA-DRB1*02) is protective against T2DM and, when studied when they have normal glucose tolerance, subjects with this HLA haplotype have higher insulin secretion compared to those without the protective haplotype. Possible autoantibody biomarkers were identified using microarrays containing 9480 proteins in plasma from Pima Indians with T2DM without the protective haplotype (n = 7) compared with those with normal glucose regulation (NGR) with the protective haplotype (n = 11). A subsequent validation phase involving 45 cases and 45 controls, matched by age, sex and specimen storage time, evaluated 77 proteins. Eleven autoantigens had higher antibody signals among T2DM subjects with the lower insulin-secretion HLA background compared with NGR subjects with the higher insulin-secretion HLA background (p<0.05, adjusted for multiple comparisons). PPARG2 and UBE2M had lowest p-values (adjusted p = 0.023) while PPARG2 and RGS17 had highest case-to-control antibody signal ratios (1.7). A multi-protein classifier involving the 11 autoantigens had sensitivity, specificity, and area under the receiver operating characteristics curve of 0.73, 0.80, and 0.83 (95% CI 0.74–0.91, p = 3.4x10-8), respectively. This study identified 11 novel autoantigens which were associated with T2DM and an HLA background associated with reduced insulin secretion. While further studies are needed to distinguish whether these antibodies are associated with insulin secretion via the HLA background, T2DM more broadly, or a combination of the two, this study may aid the search for autoantibody biomarkers by narrowing the list of protein targets. [ABSTRACT FROM AUTHOR]

Objective: The global epidemics of type 2 diabetes and obesity have been attributed to the interaction between lifestyle changes and genetic predisposition to these diseases. We compared the prevalences of type 2 diabetes and obesity in Mexican Pima Indians, presumed to have a high genetic predisposition to these diseases, to those in their non-Pima neighbors, both of whom over a 15-year period experienced a transition from a traditional to a more modern lifestyle.Research Design and Methods: Prevalence of diabetes, impaired fasting glucose, impaired glucose tolerance, and obesity in Mexican Pimas (n = 359) and non-Pima Mexicans (n = 251) were determined in 2010 using methods identical to those used in 1995.Results: During this 15-year period, age-adjusted diabetes prevalence was unchanged in Pima men (5.8% in 1995 vs. 6.1% in 2010) yet increased in non-Pima men from 0.0 to 8.6% (P < 0.05). Diabetes prevalence tended to increase in both Pima women (9.4 vs. 13.4%) and non-Pima women (4.8 vs. 9.5%). Age-adjusted prevalence of obesity increased significantly in all groups (6.6 vs. 15.7% in Pima men; 8.5 vs. 20.5% in non-Pima men; 18.9. vs 36.3% in Pima women; 29.5 vs. 42.9% in non-Pima women).Conclusions: Type 2 diabetes prevalence increased between 1995 and 2010 in non-Pima men, and to a lesser degree in women of both groups, but it did not increase in Pima men. Prevalence of obesity increased among Pimas and non-Pimas of both sexes. These changes occurred concomitantly with an environmental transition from a traditional to a more modernized lifestyle. [ABSTRACT FROM AUTHOR]