Search

Aims/hypothesis: Determining how high BMI at different time points influences the risk of developing type 2 diabetes and affects insulin secretion and insulin sensitivity is critical., Methods: By estimating childhood BMI in 441,761 individuals in the UK Biobank, we identified which genetic variants had larger effects on adulthood BMI than on childhood BMI, and vice versa. All genome-wide significant genetic variants were then used to separate the independent genetic effects of high childhood BMI from those of high adulthood BMI on the risk of type 2 diabetes and insulin-related phenotypes using Mendelian randomisation. We performed two-sample MR using external studies of type 2 diabetes, and oral and intravenous measures of insulin secretion and sensitivity., Results: We found that a childhood BMI that was one standard deviation (1.97 kg/m 2 ) higher than the mean, corrected for the independent genetic liability to adulthood BMI, was associated with a protective effect for seven measures of insulin sensitivity and secretion, including increased insulin sensitivity index (β=0.15; 95% CI 0.067, 0.225; p=2.79×10 -4 ) and reduced fasting glucose levels (β=-0.053; 95% CI -0.089, -0.017; p=4.31×10 -3 ). However, there was little to no evidence of a direct protective effect on type 2 diabetes (OR 0.94; 95% CI 0.85, 1.04; p=0.228) independently of genetic liability to adulthood BMI., Conclusions/interpretation: Our results provide evidence of the protective effect of higher childhood BMI on insulin secretion and sensitivity, which are crucial intermediate diabetes traits. However, we stress that our results should not currently lead to any change in public health or clinical practice, given the uncertainty regarding the biological pathway of these effects and the limitations of this type of study., (© 2023. The Author(s).)

Aims/hypothesis: It is well established that physical activity, abdominal ectopic fat and glycaemic regulation are related but the underlying structure of these relationships is unclear. The previously proposed twin-cycle hypothesis (TC) provides a mechanistic basis for impairment in glycaemic control through the interactions of substrate availability, substrate metabolism and abdominal ectopic fat accumulation. Here, we hypothesise that the effect of physical activity in glucose regulation is mediated by the twin-cycle. We aimed to examine this notion in the Innovative Medicines Initiative Diabetes Research on Patient Stratification (IMI DIRECT) Consortium cohorts comprised of participants with normal or impaired glucose regulation (cohort 1: N ≤ 920) or with recently diagnosed type 2 diabetes (cohort 2: N ≤ 435)., Methods: We defined a structural equation model that describes the TC and fitted this within the IMI DIRECT dataset. A second model, twin-cycle plus physical activity (TC-PA), to assess the extent to which the effects of physical activity in glycaemic regulation are mediated by components in the twin-cycle, was also fitted. Beta cell function, insulin sensitivity and glycaemic control were modelled from frequently sampled 75 g OGTTs (fsOGTTs) and mixed-meal tolerance tests (MMTTs) in participants without and with diabetes, respectively. Abdominal fat distribution was assessed using MRI, and physical activity through wrist-worn triaxial accelerometry. Results are presented as standardised beta coefficients, SE and p values, respectively., Results: The TC and TC-PA models showed better fit than null models (TC: χ 2  = 242, p = 0.004 and χ 2  = 63, p = 0.001 in cohort 1 and 2, respectively; TC-PA: χ 2  = 180, p = 0.041 and χ 2  = 60, p = 0.008 in cohort 1 and 2, respectively). The association of physical activity with glycaemic control was primarily mediated by variables in the liver fat cycle., Conclusions/interpretation: These analyses partially support the mechanisms proposed in the twin-cycle model and highlight mechanistic pathways through which insulin sensitivity and liver fat mediate the association between physical activity and glycaemic control.

Aims/hypothesis: Here, we describe the characteristics of the Innovative Medicines Initiative (IMI) Diabetes Research on Patient Stratification (DIRECT) epidemiological cohorts at baseline and follow-up examinations (18, 36 and 48 months of follow-up)., Methods: From a sampling frame of 24,682 adults of European ancestry enrolled in population-based cohorts across Europe, participants at varying risk of glycaemic deterioration were identified using a risk prediction algorithm (based on age, BMI, waist circumference, use of antihypertensive medication, smoking status and parental history of type 2 diabetes) and enrolled into a prospective cohort study (n = 2127) (cohort 1, prediabetes risk). We also recruited people from clinical registries with type 2 diabetes diagnosed 6-24 months previously (n = 789) into a second cohort study (cohort 2, diabetes). Follow-up examinations took place at ~18 months (both cohorts) and at ~48 months (cohort 1) or ~36 months (cohort 2) after baseline examinations. The cohorts were studied in parallel using matched protocols across seven clinical centres in northern Europe., Results: Using ADA 2011 glycaemic categories, 33% (n = 693) of cohort 1 (prediabetes risk) had normal glucose regulation and 67% (n = 1419) had impaired glucose regulation. Seventy-six per cent of participants in cohort 1 was male. Cohort 1 participants had the following characteristics (mean ± SD) at baseline: age 62 (6.2) years; BMI 27.9 (4.0) kg/m 2 ; fasting glucose 5.7 (0.6) mmol/l; 2 h glucose 5.9 (1.6) mmol/l. At the final follow-up examination the participants' clinical characteristics were as follows: fasting glucose 6.0 (0.6) mmol/l; 2 h OGTT glucose 6.5 (2.0) mmol/l. In cohort 2 (diabetes), 66% (n = 517) were treated by lifestyle modification and 34% (n = 272) were treated with metformin plus lifestyle modification at enrolment. Fifty-eight per cent of participants in cohort 2 was male. Cohort 2 participants had the following characteristics at baseline: age 62 (8.1) years; BMI 30.5 (5.0) kg/m 2 ; fasting glucose 7.2 (1.4) mmol/l; 2 h glucose 8.6 (2.8) mmol/l. At the final follow-up examination, the participants' clinical characteristics were as follows: fasting glucose 7.9 (2.0) mmol/l; 2 h mixed-meal tolerance test glucose 9.9 (3.4) mmol/l., Conclusions/interpretation: The IMI DIRECT cohorts are intensely characterised, with a wide-variety of metabolically relevant measures assessed prospectively. We anticipate that the cohorts, made available through managed access, will provide a powerful resource for biomarker discovery, multivariate aetiological analyses and reclassification of patients for the prevention and treatment of type 2 diabetes.

Aims/hypothesis: Many SNPs have been associated with glycaemic traits and type 2 diabetes, but their joint effects on glycaemic traits and the underlying mechanisms leading to hyperglycaemia over time are largely unknown. We aimed to investigate the association of six genetic risk scores (GRSs) with changes in plasma glucose, insulin sensitivity, insulin secretion and incident type 2 diabetes in the prospective METabolic Syndrome In Men (METSIM) study., Methods: We generated weighted GRSs for fasting plasma glucose ([FPG] GRS FPG , 35 SNPs), 2 h plasma glucose ([2hPG] GRS 2hPG , 9 SNPs), insulin secretion (GRS IS , 17 SNPs), insulin resistance (GRS IR , 9 SNPs) and BMI (GRS BMI , 95 SNPs) and a non-weighted GRS for type 2 diabetes (GRS T2D , 76 SNPs) in up to 8749 non-diabetic Finnish men. Linear regression was used to test associations of the GRSs with changes in glycaemic traits over time., Results: GRS T2D , GRS FPG and GRS IS were associated with an increase in FPG, GRS T2D with an increase in glucose AUC and a decrease in insulin secretion, and GRS 2hPG with an increase in 2hPG during the follow-up (p < 0.0017 for all models). GRS T2D , GRS FPG and GRS IS were associated with incident type 2 diabetes (p < 0.008 for all models). GRS BMI and GRS IR were not significantly associated with any changes in glycaemic traits., Conclusions/interpretation: In the METSIM follow-up study, GRS T2D , GRS FPG and GRS IS were associated with the worsening of FPG and an increase in incident type 2 diabetes. GRS T2D was additionally associated with a decrease in insulin secretion, and GRS 2hPG with an increase in 2hPG.

Aims/hypothesis: Our aim was to investigate the fasting proportions of fatty acids and estimated desaturase and elongase activities in three different lipid fractions in plasma, phospholipids (PLs), cholesteryl esters (CEs) and triacylglycerols (TGs), as predictors for the worsening of glycaemia (area under the glucose curve in an OGTT [glucose AUC]) and incident type 2 diabetes in a 5.9 year follow-up of the Metabolic Syndrome in Men population-based cohort., Methods: Fatty acid proportions were measured in plasma PL, CE and TG fractions in 1,364 Finnish men aged 45-68 years at baseline. The prospective follow-up study included only men who were non-diabetic at baseline and had data available at follow-up (n = 1,302). A total of 71 participants developed new type 2 diabetes during follow-up., Results: After adjusting for confounding factors, total saturated fatty acids, palmitoleic acid (16:1n-7), dihomo-γ-linolenic acid (20:3n-6) and estimated stearoyl-CoA desaturase 1 and Δ(6)-desaturase (D6D) enzyme activities significantly predicted the worsening of glycaemia whereas total polyunsaturated fatty acid, linoleic acid (18:2n-6) and elongase activity predicted a decrease in the glucose AUC. Estimated D6D activity and dihomo-γ-linolenic acid (20:3n-6) were associated with an increased risk of incident type 2 diabetes. Results were consistent across the three different lipid fractions. However, fatty acid proportions in the PL and CE fractions were stronger predictors for glycaemia and incident type 2 diabetes compared with fatty acid proportions in the TG fraction., Conclusions/interpretation: Selected fatty acid proportions of plasma lipid fractions and their ratios, which reflect desaturase and elongase enzyme activities, may be good biomarkers for the worsening of glycaemia and incident type 2 diabetes.

Aims/hypothesis: It is a commonly held view that chronically elevated NEFA levels adversely affect insulin secretion and insulin action (lipotoxicity). However, the effect of NEFA on beta cell function has only been explored using acute NEFA elevations. Our aim was to analyse the relationship between endogenous NEFA levels and beta cell function., Methods: In 1,267 individuals followed-up for 3 years, we measured insulin sensitivity (by clamp) and beta cell function (by C-peptide modelling during OGTT and as the acute insulin response [AIR] to IVGTT)., Results: At baseline, both fasting and insulin-suppressed NEFA levels were higher across glucose tolerance groups, while insulin sensitivity was lower, insulin output was higher, and beta cell glucose sensitivity and AIR were lower (all p < 0.0001). In multiple logistic analyses adjusting for age, BMI, WHR and glucose tolerance, both fasting and insulin-suppressed NEFA levels were inversely related to insulin sensitivity, as expected (both p < 0.0001). Furthermore, after adjusting for insulin sensitivity, insulin-suppressed NEFA were positively associated with total insulin output (p = 0.0042). In contrast, neither fasting nor insulin-suppressed NEFA were related to beta cell glucose sensitivity or AIR. At follow-up, worsening of glucose tolerance (n = 126) was predicted by lower insulin and beta cell glucose sensitivity. In this model, baseline NEFA were not significant predictors of progression., Conclusions/interpretation: In the non-diabetic state and in subjects with impaired glucose tolerance, circulating endogenous NEFA are not independently associated measures of beta cell function, and do not predict deterioration of glucose tolerance. Thus, in the Relationship Between Insulin Sensitivity and Cardiovascular Disease (RISC) cohort there is no evidence for beta cell lipotoxicity of endogenous total NEFA concentrations.

Aims/hypothesis: The aim of this work was to investigate the mechanisms underlying the risk of type 2 diabetes associated with statin treatment in the population-based Metabolic Syndrome in Men (METSIM) cohort., Methods: A total of 8,749 non-diabetic participants, aged 45-73 years, were followed up for 5.9 years. New diabetes was diagnosed in 625 men by means of an OGTT, HbA1c ≥6.5% (48 mmol/mol) or glucose-lowering medication started during the follow-up. Insulin sensitivity and secretion were evaluated with OGTT-derived indices., Results: Participants on statin treatment (N = 2,142) had a 46% increased risk of type 2 diabetes (adjusted HR 1.46 [95% CI 1.22, 1.74]). The risk was dose dependent for simvastatin and atorvastatin. Statin treatment significantly increased 2 h glucose (2hPG) and glucose AUC of an OGTT at follow-up, with a nominally significant increase in fasting plasma glucose (FPG). Insulin sensitivity was decreased by 24% and insulin secretion by 12% in individuals on statin treatment (at FPG and 2hPG <5.0 mmol/l) compared with individuals without statin treatment (p < 0.01). Decreases in insulin sensitivity and insulin secretion were dose dependent for simvastatin and atorvastatin., Conclusions/interpretation: Statin treatment increased the risk of type 2 diabetes by 46%, attributable to decreases in insulin sensitivity and insulin secretion.

Aims/hypothesis: The DIRECT (Diabetes Research on Patient Stratification) Study is part of a European Union Framework 7 Innovative Medicines Initiative project, a joint undertaking between four industry and 21 academic partners throughout Europe. The Consortium aims to discover and validate biomarkers that: (1) predict the rate of glycaemic deterioration before and after type 2 diabetes onset; (2) predict the response to diabetes therapies; and (3) help stratify type 2 diabetes into clearly definable disease subclasses that can be treated more effectively than without stratification. This paper describes two new prospective cohort studies conducted as part of DIRECT., Methods: Prediabetic participants (target sample size 2,200-2,700) and patients with newly diagnosed type 2 diabetes (target sample size ~1,000) are undergoing detailed metabolic phenotyping at baseline and 18 months and 36 months later. Abdominal, pancreatic and liver fat is assessed using MRI. Insulin secretion and action are assessed using frequently sampled OGTTs in non-diabetic participants, and frequently sampled mixed-meal tolerance tests in patients with type 2 diabetes. Biosamples include venous blood, faeces, urine and nail clippings, which, among other biochemical analyses, will be characterised at genetic, transcriptomic, metabolomic, proteomic and metagenomic levels. Lifestyle is assessed using high-resolution triaxial accelerometry, 24 h diet record, and food habit questionnaires., Conclusions/interpretation: DIRECT will yield an unprecedented array of biomaterials and data. This resource, available through managed access to scientists within and outside the Consortium, will facilitate the development of new treatments and therapeutic strategies for the prevention and management of type 2 diabetes.

Aims/hypothesis: The insulin receptor (INSR) has two protein isoforms based on alternative splicing of exon 11. INSR-A promotes cell growth whereas INSR-B predominantly regulates glucose homeostasis. In this study we investigated whether weight loss regulates INSR alternative splicing and the expression of splicing factors in adipose tissue., Methods: To determine the relative ratio of the INSR splice variants, we implemented the PCR-capillary electrophoresis method with adipose tissue samples from two weight-loss-intervention studies, the Kuopio Obesity Surgery study (KOBS, n = 108) and a very low calorie diet (VLCD) intervention (n = 32), and from the population-based Metabolic Syndrome in Men study (METSIM, n = 49)., Results: Expression of INSR-B mRNA variant increased in response to weight loss induced by both bariatric surgery (p = 1 × 10(-5)) and the VLCD (p = 1 × 10(-4)). The adipose tissue expression of INSR-B correlated negatively with fasting insulin levels in the pooled data of the three studies (p = 3 × 10(-22)). Finally, expression of several splicing factors correlated negatively with the expression of the INSR-B variant. The strongest correlation was with HNRNPA1 (p = 1 × 10(-5)), a known regulator of INSR exon 11 splicing., Conclusions/interpretation: INSR splicing is regulated by weight loss and associates with insulin levels. The effect of weight loss on INSR splicing could be mediated by changes in the expression of splicing factors.

Aims/hypothesis: Human complex metabolic traits are in part regulated by genetic determinants. Here we applied exome sequencing to identify novel associations of coding polymorphisms at minor allele frequencies (MAFs) >1% with common metabolic phenotypes., Methods: The study comprised three stages. We performed medium-depth (8×) whole exome sequencing in 1,000 cases with type 2 diabetes, BMI >27.5 kg/m(2) and hypertension and in 1,000 controls (stage 1). We selected 16,192 polymorphisms nominally associated (p < 0.05) with case-control status, from four selected annotation categories or from loci reported to associate with metabolic traits. These variants were genotyped in 15,989 Danes to search for association with 12 metabolic phenotypes (stage 2). In stage 3, polymorphisms showing potential associations were genotyped in a further 63,896 Europeans., Results: Exome sequencing identified 70,182 polymorphisms with MAF >1%. In stage 2 we identified 51 potential associations with one or more of eight metabolic phenotypes covered by 45 unique polymorphisms. In meta-analyses of stage 2 and stage 3 results, we demonstrated robust associations for coding polymorphisms in CD300LG (fasting HDL-cholesterol: MAF 3.5%, p = 8.5 × 10(-14)), COBLL1 (type 2 diabetes: MAF 12.5%, OR 0.88, p = 1.2 × 10(-11)) and MACF1 (type 2 diabetes: MAF 23.4%, OR 1.10, p = 8.2 × 10(-10))., Conclusions/interpretation: We applied exome sequencing as a basis for finding genetic determinants of metabolic traits and show the existence of low-frequency and common coding polymorphisms with impact on common metabolic traits. Based on our study, coding polymorphisms with MAF above 1% do not seem to have particularly high effect sizes on the measured metabolic traits.

Aims/hypothesis: This study investigates the role of serine/threonine protein kinase 25 (STK25), a member of the sterile 20 (STE20) superfamily of kinases, in the regulation of skeletal muscle metabolism., Methods: The effect of depleting STK25 in muscle cells was studied by reducing the mRNA and protein content of this target in the rat myoblast cell line L6 by small interfering (si)RNA. The changes in the mRNA and protein levels of several members of the fatty acid oxidative and glucose metabolic pathways were measured by quantitative real-time (qRT)-PCR and western blot. The rate of palmitate oxidation and glucose uptake was measured after transfection with siRNA for Stk25. Expression of STK25 was also evaluated in skeletal muscle biopsies from 41 white Europid men and women with normal and impaired glucose tolerance and type 2 diabetes using qRT-PCR., Results: We demonstrate that partial depletion of STK25 increases the expression of uncoupling protein 3 (Ucp3), accompanied by increased lipid oxidation, in myoblasts. In addition, a reduced level of STK25 enhances the expression of Slc2a1 (also known as Glut1), Slc2a4 (also known as Glut4) and hexokinase 2, and correspondingly, improves insulin-stimulated glucose uptake in muscle cells. Consistent with these results, significantly higher STK25 levels were observed in the skeletal muscle of type 2 diabetic patients, compared with individuals with normal glucose tolerance., Conclusions/interpretation: This is the first study indicating a possible role for STK25 in the regulation of glucose and lipid metabolism in L6 myoblasts. This kinase appears to be an interesting new mediator to be evaluated for therapeutic intervention in type 2 diabetes and related complications, as controlled increase in lipid oxidation and insulin-stimulated glucose uptake in skeletal muscle is favourable and can restore energy balance in metabolically compromised states.

Aims/hypothesis: The natural history and physiological determinants of glucose intolerance in subjects living in Europe have not been investigated. The aim of this study was to increase our understanding of this area., Methods: We analysed the data from a population-based cohort of 1,048 non-diabetic, normotensive men and women (aged 30-60 years) in whom insulin sensitivity was measured by the glucose clamp technique (M/I index; average glucose infusion rate/steady-state insulin concentration) and beta cell function was estimated by mathematical modelling of the oral glucose tolerance test at baseline and 3 years later., Results: Seventy-seven per cent of the participants had normal glucose tolerance (NGT) and 5% were glucose intolerant both at baseline and follow up; glucose tolerance worsened in 13% (progressors) and improved in 6% (regressors). The metabolic phenotype of the latter three groups was similar (higher prevalence of familial diabetes, older age, higher waist-to-hip ratio, higher fasting and 2 h plasma glucose, higher fasting and 2 h plasma insulin, lower insulin sensitivity and reduced beta cell glucose sensitivity with increased absolute insulin secretion). Adjusting for these factors in a logistic model, progression was predicted by insulin resistance (bottom M/I quartile, OR 2.52 [95% CI 1.51-4.21]) and beta cell glucose insensitivity (bottom quartile, OR 2.39 [95% CI 1.6-3.93]) independently of waist-to-hip ratio (OR 1.44 [95% CI 1.13-1.84] for one SD). At follow up, insulin sensitivity and beta cell glucose sensitivity were unchanged in the stable NGT and stable non-NGT groups, worsened in progressors and improved in regressors., Conclusions/interpretation: Glucose tolerance deteriorates over time in young, healthy Europids. Progressors, regressors and glucose-intolerant participants share a common baseline phenotype. Insulin sensitivity and beta cell glucose sensitivity predict and track changes in glucose tolerance independently of sex, age and obesity.

Aims/hypothesis: The aim of this study was to investigate the association of the rs10811661 polymorphism near the CDKN2B/CDKN2A genes with glucose tolerance, insulin sensitivity and insulin release in three samples of white people with European ancestry., Methods: Sample 1 comprised 845 non-diabetic offspring of type 2 diabetes patients recruited in five European centres participating in the EUGENE2 study. Samples 2 and 3 comprised, respectively, 864 and 524 Italian non-diabetic participants. All individuals underwent an OGTT. Screening for the rs10811661 polymorphism was performed using a TaqMan allelic discrimination assay., Results: The rs10811661 polymorphism did not show a significant association with age, BMI and insulin sensitivity. Participants carrying the TT genotype showed a significant reduction in insulin release, measured by an OGTT-derived index, compared with carriers of the C allele, in the three samples. When these results were pooled with those of three published studies, and meta-analysed with a random-effects model, the T allele was significantly associated with reduced insulin secretion (-35.09 [95% CI 14.68-55.52], p = 0.0008 for CC+CT vs TT; and -29.45 [95% CI 9.51-49.38], p = 0.0038, for the additive model). In addition, in our three samples, participants carrying the TT genotype exhibited an increased risk for impaired glucose tolerance (IGT) compared with carriers of the C allele (OR 1.55 [95% CI 1.20-1.95] for the meta-analysis of the three samples)., Conclusions/interpretation: Our data, together with the meta-analysis of previously published studies, show that the rs10811661 polymorphism is associated with impaired insulin release and IGT, suggesting that this variant may contribute to type 2 diabetes by affecting beta cell function.

Aims/hypothesis: In epidemiological and genetic studies surrogate indices are needed to investigate insulin resistance in different insulin-sensitive tissues. Our objective was to develop a surrogate index for hepatic insulin resistance., Methods: A sample of 368 non-diabetic participants (age 43.0 ± 8.2 years, BMI 26.0 ± 4.0 kg/m(2); mean ± SD) whose endogenous glucose production (EGP) was measured with [6-6(2)H(2)]glucose in the fasting state and during the euglycaemic-hyperinsulinaemic clamp were included in the study. EGP multiplied by fasting plasma insulin (FPI) concentration was the reference measurement for liver insulin resistance (liver IR). Liver IR index was calculated with linear regression analysis including age, obesity indices, lipids, lipoproteins and several variables regulating glucose metabolism., Results: The following variables were significantly associated with liver IR in multiple forward stepwise regression analysis: insulin AUC in an OGTT, fat mass, HDL-cholesterol and BMI. Liver IR index correlated significantly with EGP×FPI (r = 0.65, p < 0.001). In participants with abnormal glucose tolerance, the correlation of liver IR with EGP×FPI was slightly stronger (r = 0.69, p < 0.001) than in those with normal glucose tolerance (r = 0.62, p < 0.001)., Conclusions/interpretation: We generated a novel surrogate index for liver insulin resistance correlating strongly with EGP × FPI.

Aims/hypothesis: Of the confirmed type 2 diabetes susceptibility loci only a few are known to affect insulin sensitivity. We examined the association of indices of hepatic and adipocyte insulin resistance (IR) with 19 confirmed type 2 diabetes risk loci in a large population-based study., Methods: Non-diabetic participants (n = 8,460, age 57.3 ± 7.0 years, BMI 26.8 ± 3.8 kg/m(2); mean ± SD) from a population-based cohort underwent an OGTT. Of them, 6,733 non-diabetic men were genotyped for single nucleotide polymorphisms (SNPs) in or near PPARG2 (also known as PPARG), KCNJ11, TCF7L2, SLC30A8, HHEX, CDKN2B, IGF2BP2, CDKAL1, HNF1B, WFS1, JAZF1, CDC123, TSPAN8, THADA, ADAMTS9, NOTCH2, KCNQ1, MTNR1B and SNP rs7480010. We investigated hepatic IR with a new index of liver IR. The adipocyte IR index was defined as a product of fasting NEFA and plasma insulin levels., Results: Type 2 diabetes risk SNPs in or near KCNJ11 and HHEX were significantly (p < 0.0013), and those in or near CDKN2B, NOTCH2 and MTNR1B were nominally (p < 0.05), associated with decreased liver IR index. The Pro12 allele of PPARG2 was significantly associated with a high adipocyte IR index and nominally associated with high liver IR., Conclusions/interpretation: The Pro12 allele of PPARG2 seems to impair insulin's antilipolytic effect, leading to high NEFA release in the fasting state and IR. In addition, the type 2 diabetes risk alleles of KCNJ11 and HHEX, which are known to impair insulin secretion, were associated with increased hepatic insulin sensitivity.

Aims/hypothesis: Rare mutations in the gene HNF4A, encoding the transcription factor hepatocyte nuclear factor 4α (HNF-4A), account for ~5% of cases of MODY and more frequent variants in this gene may be involved in multifactorial forms of diabetes. Two low-frequency, non-synonymous variants in HNF4A (V255M, minor allele frequency [MAF] ~0.1%; T130I, MAF ~3.0%)-known to influence downstream HNF-4A target gene expression-are of interest, but previous type 2 diabetes association reports were inconclusive. We aimed to evaluate the contribution of these variants to type 2 diabetes susceptibility through large-scale association analysis., Methods: We genotyped both variants in at least 5,745 cases and 14,756 population controls from the UK and Denmark. We also undertook an expanded association analysis that included previously reported and novel genotype data obtained in Danish, Finnish, Canadian and Swedish samples. A meta-analysis incorporating all published association studies of the T130I variant was subsequently carried out in a maximum sample size of 14,279 cases and 26,835 controls., Results: We found no association between V255M and type 2 diabetes in either the initial (p = 0.28) or the expanded analysis (p = 0.44). However, T130I demonstrated a modest association with type 2 diabetes in the UK and Danish samples (additive per allele OR 1.17 [95% CI 1.08-1.28]; p = 1.5 × 10⁻⁴), which was strengthened in the meta-analysis (OR 1.20 [95% CI 1.10-1.30]; p = 2.1 × 10⁻⁵)., Conclusions/interpretation: Our data are consistent with T130I as a low-frequency variant influencing type 2 diabetes risk, but are not conclusive when judged against stringent standards for genome-wide significance. This study exemplifies the difficulties encountered in association testing of low-frequency variants.

Aims/hypothesis: Physical activity reduces cardiovascular disease (CVD) and total mortality rates in patients with type 2 diabetes. However, it is not known whether or not the effects of physical activity on mortality rates depend on the presence of proteinuria in type 2 diabetic patients., Methods: We prospectively followed up 577 patients with type 2 diabetes who were aged 45 to 64 years and were free of CVD at baseline. Participants were stratified according to the presence of proteinuria (300 mg/l) and the degree of physical activity (0-4 metabolic equivalent tasks [MET] or >4 MET). The Cox proportional hazards model was used to estimate the association of physical activity and proteinuria with risk of mortality., Results: During the 18-year follow-up, 356 patients died, of whom 217 died from CVD. Physically more active patients had significantly reduced total, CVD and CHD mortality rates if they did not have proteinuria. In contrast, physically active proteinuric patients had significantly increased total and CVD mortality rates (HR 1.83, 95% CI 1.00-3.36, p=0.049) in univariate analyses, with HR 2.43 (95% CI 1.09-5.40, p=0.030) in multivariate analyses., Conclusions/interpretation: Physical activity reduces total and CVD mortality rates in type 2 diabetic patients without proteinuria. However, in proteinuric patients, no protective effect was observed. Larger studies are needed to confirm the latter finding and to define which exercise intensity leads to possible harmful effects.

Aims/hypothesis: It is commonly thought that hyperglycaemia results from insufficient compensation of insulin secretion for insulin resistance. To verify this hypothesis, we assessed beta cell function and insulin sensitivity (IS) in a large cohort of volunteers with normal glucose tolerance (NGT) or impaired glucose regulation (IGR), i.e. impaired glucose tolerance or impaired fasting glucose., Methods: In men and women with NGT (n=1,123) or IGR(n=156) (age 44 +/- 8 years, BMI 25+/-4 kg/m2, mean +/- SD)we measured: (1) IS by clamp; (2) insulin secretion rates(ISR) and beta cell glucose sensitivity (=slope of the insulin secretion/plasma glucose dose-response) by C-peptide deconvolution and OGTT modelling; and (3) acute insulin response to intravenous glucose., Results: After controlling for centre, sex, age and BMI, fasting and total ISR were inversely related to IS in both groups,whereas beta cell glucose sensitivity was not. Acute insulin response was reciprocally related to IS in both groups, but the relationships were incompatible with inadequate compensation and significance was lost after controlling for fasting ISR. InIGR vs NGT, IS was impaired (92 [75] vs 133 [86] micromol min(-1)[kg fat-free mass](-1) [nmol/l](-1), median [interquartile range],p<0.0001) as was beta cell glucose sensitivity (69 [46] vs 119[83] pmol min(-1) m(-2) [nmol/l](-1), p<0.0001), whereas fasting and total ISR were increased (35% and 25%, respectively, p<0.0001). In fully adjusted models, beta cell glucose sensitivity was the strongest determinant of OGTT glucose levels., Conclusions/interpretation: Insulin resistance normally upregulates the secretory tone, with no evidence of defective compensation in IGR. In contrast, beta cell glucose sensitivity is independent of insulin resistance, but a key determinant of glucose tolerance. This suggests that hyperglycaemia results from an intrinsic beta cell defect rather than from inadequate compensation for insulin resistance.

Aims/hypothesis: We investigated whether variation in MTNR1B, which was recently identified as a common genetic determinant of fasting glucose levels in healthy, diabetes-free individuals, is associated with measures of beta cell function and whole-body insulin sensitivity., Methods: We studied 1,276 healthy individuals of European ancestry at 19 centres of the Relationship between Insulin Sensitivity and Cardiovascular disease (RISC) study. Whole-body insulin sensitivity was assessed by euglycaemic-hyperinsulinaemic clamp and indices of beta cell function were derived from a 75 g oral glucose tolerance test (including 30 min insulin response and glucose sensitivity). We studied rs10830963 in MTNR1B using additive genetic models, adjusting for age, sex and recruitment centre., Results: The minor (G) allele of rs10830963 in MTNR1B (frequency 0.30 in HapMap Centre d'Etude du Polymorphisme [Utah residents with northern and western European ancestry] [CEU]; 0.29 in RISC participants) was associated with higher levels of fasting plasma glucose (standardised beta [95% CI] 0.17 [0.085, 0.25] per G allele, p = 5.8 x 10(-5)), consistent with recent observations. In addition, the G-allele was significantly associated with lower early insulin response (-0.19 [-0.28, -0.10], p = 1.7 x 10(-5)), as well as with decreased beta cell glucose sensitivity (-0.11 [-0.20, -0.027], p = 0.010). No associations were observed with clamp-assessed insulin sensitivity (p = 0.15) or different measures of body size (p > 0.7 for all)., Conclusions/interpretation: Genetic variation in MTNR1B is associated with defective early insulin response and decreased beta cell glucose sensitivity, which may contribute to the higher glucose levels of non-diabetic individuals carrying the minor G allele of rs10830963 in MTNR1B.

Aims/hypothesis: Early environmental factors and genetic variants have been reported to be involved in the pathogenesis of type 2 diabetes. The aim of this study was to investigate whether there is an interaction between birthweight and common variants in the TCF7L2, HHEX, PPARG, KCNJ11, SLC30A8, IGF2BP2, CDKAL1, CDKN2A/2B and JAZF1 genes in the risk of developing type 2 diabetes., Methods: A total of 2,003 participants from the Helsinki Birth Cohort Study, 311 of whom were diagnosed with type 2 diabetes by an OGTT, were genotyped for the specified variants. Indices for insulin sensitivity and secretion were calculated., Results: Low birthweight was associated with type 2 diabetes (p = 0.008) and impaired insulin secretion (p = 0.04). Of the tested variants, the risk variant in HHEX showed a trend towards a low birthweight (p = 0.09) and the risk variant in the CDKN2A/2B locus was associated with high birthweight (p = 0.01). The TCF7L2 risk allele was associated with increased risk of type 2 diabetes. Pooling across all nine genes, each risk allele increased the risk of type 2 diabetes by 14%. [corrected] Risk variants in the HHEX, CDKN2A/2B and JAZF1 genes interacted with birthweight, so that the risk of type 2 diabetes was highest in those with lower birthweight (p

Aims/hypothesis: A recent genome-wide association study identified the SLC30A8 rs13266634 polymorphism encoding an Arg325Trp polymorphism in the zinc transporter protein member 8 (ZnT-8) to be associated with type 2 diabetes. Here, we investigate whether the polymorphism is related to altered insulin release in response to intravenous and oral glucose loads in non-diabetic offspring of type 2 diabetic patients., Methods: We genotyped SLC30A8 rs13266634 in 846 non-diabetic offspring of type 2 diabetic patients from five different white populations: Danish (n = 271), Finnish (n = 217), German (n = 149), Italian (n = 109) and Swedish (n = 100). Participants were subjected to both IVGTTs and OGTTs, and measurements of insulin sensitivity., Results: Homozygous carriers of the major type 2 diabetes C risk-allele showed a 19% decrease in first-phase insulin release (0-10 min) measured during the IVGTT (CC 3,624 +/- 3,197; CT 3,763 +/- 2,674; TT 4,478 +/- 3,032 pmol l(-1) min(-1), mean +/- SD; p = 0.007). We found no significant genotype effect on insulin release measured during the OGTT or on estimates of insulin sensitivity., Conclusions/interpretation: Of European non-diabetic offspring of type 2 diabetes patients, 46% are homozygous carriers of the Arg325Trp polymorphism in ZnT-8, which is known to associate with type 2 diabetes. These diabetes-prone offspring are characterised by a 19% decrease in first-phase insulin release following an intravenous glucose load, suggesting a role for this variant in the pathogenesis of pancreatic beta cell dysfunction.

Aims/hypothesis: We examined the phenotype of individuals with impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT) with regard to insulin release and insulin resistance., Methods: Non-diabetic offspring (n=874; mean age 40+/-10.4 years; BMI 26.6+/-4.9 kg/m(2)) of type 2 diabetic patients from five different European Centres (Denmark, Finland, Germany, Italy and Sweden) were examined with regard to insulin sensitivity (euglycaemic clamps), insulin release (IVGTT) and glucose tolerance (OGTT). The levels of glucagon-like peptide-1 (GLP-1) and gastric inhibitory polypeptide (GIP) were measured during the OGTT in 278 individuals., Results: Normal glucose tolerance was found in 634 participants, while 110 had isolated IFG, 86 had isolated IGT and 44 had both IFG and IGT, i.e. about 28% had a form of reduced glucose tolerance. Participants with isolated IFG had lower glucose-corrected first-phase (0-10 min) and higher second-phase insulin release (10-60 min) during the IVGTT, while insulin sensitivity was reduced in all groups with abnormal glucose tolerance. Similarly, GLP-1 but not GIP levels were reduced in individuals with abnormal glucose tolerance., Conclusions/interpretation: The primary mechanism leading to hyperglycaemia in participants with isolated IFG is likely to be impaired basal and first-phase insulin secretion, whereas in isolated IGT the primary mechanism leading to postglucose load hyperglycaemia is insulin resistance. Reduced GLP-1 levels were seen in all groups with abnormal glucose tolerance and were unrelated to the insulin release pattern during an IVGTT.

Aims/hypothesis: AGEs, modification products formed by glycation or glycoxidation of proteins and lipids, have been linked to premature atherosclerosis in patients with diabetes. We investigated whether increased serum levels of AGEs predict total, cardiovascular (CVD) or CHD mortality in a population-based study., Subjects and Methods: Serum levels of AGEs were determined by immunoassay in a random sample of 874 Finnish diabetic study participants (488 men, 386 women), aged 45-64 years. These participants were followed for 18 years for total, CVD and CHD mortality., Results: Multivariate Cox regression models revealed that serum levels of AGEs were significantly associated with total (p = 0.002) and CVD mortality (p = 0.021) in women, but not in men. Serum levels of AGEs in the highest sex-specific quartile predicted all-cause (hazards ratio [HR] 1.51; 95% confidence intervals [CI], 1.14-1.99; p = 0.004), CVD (HR 1.56; 95% CI 1.12-2.19; p = 0.009), and CHD (HR 1.68; 95% CI 1.11-2.52; p = 0.013) mortality in women, even after adjustment for confounding factors, including high-sensitivity C-reactive protein., Conclusions/interpretation: Increased serum levels of AGEs predict total and CVD mortality in women with type 2 diabetes.

Aims/hypothesis: We investigated the association of variants of the transcription factor 7-like 2 (TCF7L2) gene with: (1) incident diabetes in the Finnish Diabetes Prevention Study (DPS, Study I); (2) type 2 diabetes and impaired glucose regulation (i.e. IGT or IFG) in a cross-sectional study (Study II); and (3) insulin secretion, insulin sensitivity and adipose tissue expression of TCF7L2 in offspring of type 2 diabetic probands (III)., Subjects and Methods: Study I (the DPS) included 507 individuals with IGT who were randomly allocated to control and intervention groups and followed for an average of 3.9 years to monitor for progression to diabetes. Study II was a population-based cross-sectional study of 1,766 men, aged 50-70 years, randomly selected from the population of Kuopio, eastern Finland. Study III included 238 non-diabetic offspring of patients with type 2 diabetes. Genotyping of rs12255372 and rs7903146 of TCF7L2 was carried out., Results: In the DPS, the TT genotype of rs12255372 was significantly associated with an adjusted 2.85-fold risk (95% CI 1.17-6.95, p = 0.021) of incident diabetes in the control group, but not in the intervention group. In Study II, the adjusted odds ratio in subjects with the TT genotype was 3.40 (1.45-7.97, p = 0.005) for the comparison of diabetic subjects with normoglycaemic subjects. The T allele of rs12255372 was significantly associated with decreased insulin secretion (Studies II, III). Expression of TCF7L2 in adipose tissue tended to be lower in subjects with the TT risk genotypes of rs12255372 and rs7903146., Conclusions/interpretation: The variant of rs12255372 of TCF7L2 was associated with incident type 2 diabetes in the DPS and in a separate population-based cross-sectional study. Impaired insulin secretion is likely to be the main cause for our findings.

Aims/hypothesis: Adiponectin is a circulating peptide derived from adipose tissue. It mediates its insulin-sensitising and anti-atherogenic effects on target tissues through two known receptors, adiponectin receptors 1 and 2 (ADIPOR1; ADIPOR2), which are encoded by the genes ADIPOR1 and ADIPOR2. Our aim was to study the association of ADIPOR1 gene variations with body size and risk of type 2 diabetes in subjects with impaired glucose tolerance, who participated in the Finnish Diabetes Prevention Study (DPS)., Subjects and Methods: We selected seven single nucleotide polymorphisms (SNPs) of the ADIPOR1 gene to perform association studies with anthropometrics and metabolic parameters at baseline, and with the risk of type 2 diabetes during the 3-year follow-up in the DPS study population. Both single SNP analysis and haplotype effects were studied., Results: Three out of seven markers studied (rs10920534, rs22757538 and rs1342387) were significantly associated with various body size measurements including weight, height, waist and hip circumference, sagittal diameter and body mass index. Furthermore, three markers (rs10920534, rs12045862 and rs7539542), of which two were different from those associating with body size, were linked to fasting and 2-h insulin levels, particularly in men at baseline. The haplotype analysis with five markers revealed seven major haplotypes in the DPS study population. The haplotype effects on body size measures were in line with those of single SNP analysis. However, none of the markers were associated with the risk of type 2 diabetes., Conclusions/interpretation: Our findings suggest that ADIPOR1 has a putative role in the development of body size, and that traits for central adiposity and insulin resistance may be dissociated from each other.

Aims/hypothesis: The mechanisms by which the calpain-10 gene (CAPN10) affects the risk of type 2 diabetes are unclear. Therefore, we investigated the effects of four polymorphisms in CAPN10 (single nucleotide polymorphism [SNP]-43, SNP-44, Insertion/Deletion [Indel]-19 and SNP-63) on insulin secretion, insulin action and abdominal fat distribution in offspring of patients with type 2 diabetes., Subjects and Methods: Insulin secretion was determined by an IVGTT, insulin action by the hyperinsulinaemic-euglycaemic clamp and abdominal fat distribution by computed tomography in 158 non-diabetic offspring (age 34.9+/-6.3 years [mean+/-SD], BMI 26.2+/-4.9 kg/m(2)) of type 2 diabetic patients., Results: SNP-43 (p=0.009 over the three genotypes, adjusted for age, sex, BMI and family relationship) and haplotypes carrying the A allele of SNP-43 were associated with intra-abdominal fat area. The A allele of SNP-43 was associated with intra-abdominal fat area in men (p=0.014) but not in women. SNP-44, InDel-19 and SNP-63 were not associated with intra-abdominal fat area or insulin action. Furthermore, we demonstrated in a separate sample of middle-aged men (n=234) who had a history of type 2 diabetes in first-degree relatives that the A allele of SNP-43 was associated with a large waist circumference, and high insulin levels in an OGTT., Conclusions/interpretation: SNP-43 of CAPN10 may contribute to the risk of diabetes by regulating abdominal obesity in subjects with high risk of type 2 diabetes.

Aims/hypothesis: Proteinuria predicts cardiovascular disease (CVD), but it is unclear whether this is explained by the association of the metabolic syndrome with proteinuria. Therefore, we investigated proteinuria and the metabolic syndrome as independent predictors of CVD death in men and women., Methods: The cohort comprised 574 non-diabetic men, 707 non-diabetic women, 371 diabetic men and 349 diabetic women, all free of CVD at baseline. Modified World Health Organization criteria were used to define the metabolic syndrome, and a urinary protein concentration of >or=0.1 g/l (or >or=0.2 g/l) to define proteinuria. The endpoint was CVD mortality during the 18-year follow-up., Results: Among non-diabetic men, CVD mortality per 1,000 person-years was as follows: no metabolic syndrome, no urinary protein group: 5.3; no metabolic syndrome, positive for urinary protein: 8.9; positive for metabolic syndrome, no urinary protein: 13.3; and positive for metabolic syndrome and urinary protein: 14.9. For non-diabetic women the corresponding values were: 0.9, 2.3, 4.9 and 7.9, respectively. Among diabetic men, CVD mortality per 1,000 person-years was 15.2, 32.5, 23.6 and 42.0 for the respective groups. Among diabetic women it was 25.3, 38.0, 26.3 and 40.3 (urinary protein in all cases defined as >or=0.1 g/l). In multivariate Cox models including both urinary protein and metabolic syndrome, the hazard ratios (HRs, 95% CI) of proteinuria for CVD mortality were 1.5 (0.9-2.4) in non-diabetic men, 1.8 (0.8-4.2) in non-diabetic women, 1.6 (1.0-2.6) in diabetic men and 1.6 (1.1-2.3) in diabetic women. Urinary protein as a continuous variable was associated with CVD mortality in all groups. The corresponding HRs for metabolic syndrome were: 1.6 (0.9-2.7), 4.0 (1.7-9.7), 1.5 (1.1-2.0) and 1.1 (0.8-1.5)., Conclusions/interpretation: Proteinuria predicted CVD mortality independently of the presence of metabolic syndrome in non-diabetic and diabetic subjects. Metabolic syndrome predicted CVD mortality in non-diabetic women and in diabetic men, independently of the presence of proteinuria.

Aims/hypothesis: One-third of normoalbuminuric type 1 diabetic patients show immunoreactive nephrin in urine. Offspring of type 2 diabetic patients are insulin-resistant and susceptible to the development of diabetes. We investigated whether the offspring of type 2 diabetic patients show nephrin in urine and whether possible nephrinuria is associated with insulin resistance., Methods: Urinary proteins from timed overnight urine collections from 128 offspring of type 2 diabetic patients and 9 control subjects were analysed by western blotting using an antibody against nephrin. Glucose metabolism was assessed by OGTT and IVGTT and the euglycaemic-hyperinsulinaemic clamp technique., Results: Of the offspring, 12.5% were strongly and 14.1% weakly positive for a 100-kDa urinary protein. All controls were negative. During the first 10 min of an IVGTT, the offspring strongly positive for the urinary protein had a higher insulin response than the offspring without the protein (3,700 vs 2,306 pmol l(-1)min(-1), p=0.007). Insulin sensitivity (the rate of whole-body glucose uptake divided by the steady-state insulin level x 100) was lower among the offspring strongly positive for the urinary protein than among the offspring negative for the protein (11.3 vs 15.8 micromol kg(-1)min(-1)pmol(-1)l(-1), p=0.008)., Conclusions/interpretation: A 100-kDa urinary protein detectable with a nephrin antibody is associated with insulin resistance in offspring of type 2 diabetic patients.

Aims/hypothesis: Decreased expression of the peroxisomal proliferator activated receptor gamma coactivator 1 alpha gene (PPARGC1A) is found in patients with type 2 diabetes, and variants in this gene have been linked with type 2 diabetes. Therefore, we investigated the effects of single nucleotide polymorphisms in PPARGC1A on body composition and glucose tolerance and on insulin sensitivity and secretion., Methods: Non-diabetic offspring (n=156, age 34.9+/-0.5 years [mean+/-SEM], BMI 26.2+/-0.4 kg/m2) underwent an OGTT and an IVGTT and the hyperinsulinaemic-euglycaemic clamp. The promoter and coding regions of PPARGC1A were sequenced., Results: Two haplotype blocks in PPARGC1A were observed, one in the promoter region (G-1774A, A-1679G, T-1422C, A-1278G, C-543A) and one in the coding region and 3' regions (Thr394Thr, Asp475Asp, Gly482Ser, Thr528Thr, Thr612Met, G+2381A). The coding region haplotype carrying the rare allele in codons 482 and 528 was associated with elevated glucose levels in an OGTT (p=0.024, adjusted for age, sex and BMI) and a haplotype carrying the rare alleles in codons 394 and 475 was associated with low BMI (p=0.033), high rates of whole-body glucose uptake (p=0.045) and low glucose levels in the OGTT (p=0.037)., Conclusions/interpretation: We conclude that PPARGC1A is likely to contribute to the risk of diabetes in offspring of patients with type 2 diabetes.

Aim/hypothesis: We investigated the effects of the common polymorphisms in the peroxisome proliferator-activated receptor gamma2 (PPAR-gamma2; Pro12Ala) and in PPAR-gamma coactivator 1alpha (PGC-1alpha; Gly482Ser) genes on the conversion from impaired glucose tolerance to type 2 diabetes in participants in the STOP-NIDDM trial. This trial aimed to study the effect of acarbose in the prevention of type 2 diabetes., Methods: Genotyping was performed in 770 study subjects whose DNA was available. The Gly482Ser variant in the PGC-1alpha gene was determined with the polymerase chain reaction amplification, Hpa II enzyme digestion, and gel electrophoresis. The Pro12Ala polymorphism of the PPAR-gamma2 gene was determined by the polymerase chain reaction-single-strand conformation polymorphism analysis., Results: The Pro12Pro genotype of the PPAR-gamma2 gene predicted the conversion to diabetes in women in the acarbose group (odds ratio 2.89, 95% CI 1.20 to 6.96; p=0.018). The 482Ser allele of the PGC-1alpha gene had a significant interaction with the mode of treatment (p=0.012), and in the placebo group the 482Ser allele was associated with a 1.6-fold higher risk for type 2 diabetes compared to the Gly482Gly genotype (95% CI 1.06 to 2.33; p=0.023). Acarbose prevented the development of diabetes independently of the genotype of the PPAR-gamma2 gene, but only the carriers of the 482Ser allele of the PGC-1alpha gene were responsive to acarbose treatment., Conclusion/interpretation: We conclude that the Pro12Pro genotype of the PPAR-gamma2 gene and the 482Ser allele of the PGC-1alpha gene are associated with the conversion from impaired glucose tolerance to type 2 diabetes in the STOP-NIDDM trial.

Aims/hypothesis: Impaired insulin secretion has a strong genetic component. In this study we investigated whether the 12Glu9 polymorphism in the gene encoding the alpha2B-adrenergic receptor ( ADRA2B) is associated with insulin secretion and/or the incidence of Type 2 diabetes in individuals with impaired glucose tolerance., Methods: We investigated a total of 506 subjects with impaired glucose tolerance participating in the Finnish Diabetes Prevention Study (DPS). Participants were randomly assigned to an intervention group or a control group. Anthropometric measurements and an oral glucose tolerance test were performed at baseline and at annual follow-up. In a subgroup of patients (n=83), a frequently sampled intravenous glucose tolerance test (FSIGT) was performed at baseline., Results: All patients had similar anthropometric measurements and insulin and glucose levels at baseline. Multiple logistic regression analysis revealed significant interaction (p=0.003) between study group and genotype across the entire study population. In the control group, subjects with the Glu9 allele had an increased risk of developing Type 2 diabetes compared with subjects with the Glu12/12 genotype (odds ratio [OR]=2.68, 95% CI 1.02-7.09, p=0.047 for Glu12/12, and OR=5.17, 95% CI 1.76-15.21, p=0.003 for Glu9/9). This increased risk was not observed in the intervention group, who showed significant weight loss during the trial. In the subgroup who underwent the FSIGT, subjects with the Glu9/9 genotype showed the lowest acute insulin response (p=0.005 for trend)., Conclusions/interpretation: The 12Glu9 polymorphism of ADRA2B is associated with impaired first-phase insulin secretion and may predict the development of Type 2 diabetes in subjects with impaired glucose tolerance who are not subjected to a lifestyle intervention.

The STOP-NIDDM Trial has shown that acarbose treatment in subjects with impaired glucose tolerance is associated with a significant risk reduction in the development of diabetes, hypertension and cardiovascular complications. Kaiser and Sawicki have accused the investigators of the STOP-NIDDM Trial of major biases in the conduct of the study, of manipulating the data and of conflict of interest. The aim of this paper is to present data and explanations refuting these allegations. In the STOP-NIDDM Trial, 61 subjects were excluded from the efficacy analysis before unblinding for legitimate reasons: failure to satisfy major entry criteria (n=17) and lack of post-randomisation data (n=44). Blinding and randomisation were carried out by an independent biostatistician. Titration of placebo/acarbose is well described in the protocol and in the study design paper. Of the study population, 9.3% had a fasting plasma glucose of > or =7.0 mmol/l at screening and could have been diabetic according to the new diagnostic criteria. However, even if these subjects are excluded, patients having acarbose treatment still saw a significant risk reduction in the development of diabetes (p=0.0027). The changes in weight are consistent in different publications and are related to different times of follow-up and assessment. Weight change does have an effect on the development of diabetes, but acarbose treatment is still effective even after adjusting for this (p=0.0063). The cardiovascular endpoints were a clearly designated assessment in the original protocol, and only those defined in the protocol and ascertained by the independent Cardiovascular Event Adjudication Committee were used in the analysis. Hypertension was defined according to the most recent diagnostic criteria. The STOP-NIDDM Trial results are scientifically sound and credible. The investigators stand strongly behind these results demonstrating that acarbose treatment is associated with a delay in the development of diabetes, hypertension and cardiovascular complications in a high-risk population with IGT.

Aims/hypothesis: Type 2 diabetes is a complex disorder with strong heritability. The aim of our study was to investigate whether common polymorphisms in the genes regulating the early insulin signalling pathway (insulin; A-23T, insulin-like growth factor 1 receptor [IGF-1R]; GAG1013GAA, plasma cell membrane glycoprotein 1 [PC-1]; K121Q, insulin receptor substrate [IRS-1]; G972R, insulin receptor substrate 2 [IRS-2]; G1057D and phosphatidylinositol 3-kinase p85 alpha [PI3K]; M326I) affect the weight change and development of Type 2 diabetes in the Finnish Diabetes Prevention Study., Methods: We screened for the polymorphisms in 490 overweight subjects with impaired glucose tolerance whose DNA was available from the Finnish Diabetes Prevention Study. These subjects were randomly allocated into a control group and an intervention group characterised by intensive, individualised diet and exercise., Results: In carriers of the GAA1013GAA genotype of IGF-1R, the R972 allele of IRS-1 and the D1057D genotype of IRS-2, lifestyle intervention did not lead to significant differences in weight loss between the intervention and control groups, implying a role of these risk genotypes in the regulation of body weight. We observed a statistically significant difference in the conversion rate from IGT to diabetes between the genotypes of the IGF-1R gene (GAG1013GAG: 18.6%, GAG1013GAA: 10.4%, GAA1013GAA: 19.5%, p=0.033). Common polymorphisms in the insulin, PC-1 and PI3K genes did not regulate weight change or conversion to diabetes., Conclusions/interpretation: The common polymorphisms of the IGF-1R, IRS-1 and IRS-2 genes may modify the weight change response to a lifestyle intervention but not the conversion from IGT to Type 2 diabetes, whereas IGF-1R may also regulate the risk of developing Type 2 diabetes.

Aims/hypothesis: ATP-sensitive potassium (K(ATP)) channels are crucial for the regulation of insulin secretion from pancreatic beta cells and mutations in either the Kir6.2 or SUR1 subunit of this channel can cause congenital hyperinsulinism (CHI). The aim of this study was to analyse the functional consequences of four CHI mutations (A1457T, V1550D and L1551V in SUR1, and K67N in Kir6.2) recently identified in the Finnish population., Methods: Wild type or mutant Kir6.2 and SUR1 subunits were coexpressed in Xenopus oocytes. The functional properties of the channels were examined by measuring currents in intact oocytes or giant inside-out membrane patches. Surface expression was measured by enzyme-linked immunosorbance assay, using HA-epitope-tagged subunits., Results: Two mutations (A1457T and V1550D) prevented trafficking of the channel to the plasma membrane. The L1551V mutation reduced surface expression 40-fold, and caused loss of MgADP and diazoxide activation. Both these factors will contribute to the lack of K(ATP) current activation observed in response to metabolic inhibition in intact oocytes. The L1551V mutation also increased the channel open probability, thereby producing a reduction in ATP-sensitivity (from 10 micro mol/l to 120 micro mol/l). The fourth mutation (K67N mutation in Kir6.2) did not affect surface expression nor alter the properties of K(ATP) channels in excised patches, but resulted in a reduced K(ATP) current amplitude in intact cells on metabolic inhibition, through an unidentified mechanism., Conclusion/interpretation: The four CHI mutations disrupted K(ATP) channel activity by different mechanisms. Our results are discussed in relation to the CHI phenotype observed in patients with these mutations.

Aims/hypothesis: Information on the association of hyperinsulinaemia with coronary heart disease (CHD) in patients with Type II (non-insulin-dependent) diabetes is limited and controversial. Therefore, we carried out a prospective study to examine the predictive value of fasting plasma insulin and "hyperinsulinaemia cluster" with regard to the risk of CHD mortality., Methods: At baseline risk factors for CHD were determined in 902 patients aged 45 to 64 years with Type II diabetes not treated by insulin (499 men and 403 women). These patients were followed up to 7 years for CHD mortality., Results: Coronary heart disease mortality (16.2% in men, 9.2% in women) increased significantly in men with increasing plasma insulin tertiles (p = 0.006) and in both sexes combined (p = 0.010) but not in women (p = 0.090). The predictive value of hyperinsulinaemia with regard to death from CHD was independent of conventional cardiovascular risk factors but not of risk factors clustering with hyperinsulinaemia. By applying factor analysis and principal component analysis we showed that "hyperinsulinaemia cluster" (a factor having high positive loadings for body mass index, triglycerides and insulin; and a high negative loading for high-density lipoprotein cholesterol) was predictive of death from CHD in patients with Type II diabetes (hazard ratio with 95% confidence intervals 1.43 (1.18, 1.73), p < 0.001)., Conclusion/interpretation: Our results support the notion that cardiovascular risk factors clustering with endogenous hyperinsulinaemia increase the risk of death from CHD in patients with Type II diabetes not treated with insulin.

Aims/hypothesis: This study was undertaken to investigate metabolic and genetic characteristics of latent autoimmune diabetes in adults (LADA)., Methods: We evaluated insulin secretory capacity with oral and intravenous glucose tolerance tests (early insulin response) and hyperglycaemic clamp (insulin secretory capacity) and the rates of whole body glucose uptake with the euglycaemic clamp, HLA-DQB1 genotypes (time-resolved fluorescence) and islet cell antibodies (ICA) (immunofluorescence) and antibodies to glutamic acid decarboxylase (GAD) (radio-immunoprecipitation) in 36 non-diabetic offspring (LADA-offspring) of patients with Type II (non-insulin-dependent) diabetes mellitus who tested positive for ICA and/or GAD antibodies during the 10-year follow-up from the diagnosis and in 19 healthy control subjects without a family history of diabetes., Results: The early insulin response during the first 10 min of an intravenous glucose tolerance test was about 40% lower in the LADA-offspring than in the control group (p = 0.008). Insulin secretory capacity in the hyperglycaemic clamp was also about 30% lower in the LADA-offspring (p = 0.048). The rates of whole body glucose uptake were similar in both groups. The frequency of low risk HLA-DQB1 genotypes was higher in the LADA-offspring than among Finnish healthy blood donors (p = 0.033). The risk conferring genotypes were associated with the lowest tertile of insulin secretory capacity in the LADA-offspring (p = 0.032). There were no associations between the autoantibodies and early insulin response or insulin secretory capacity within the study groups., Conclusion/interpretation: We conclude that LADA is a familial disease involving most likely gene defects leading to a slow progressive beta-cell destruction and insulin deficiency.

Unlabelled: AIMS/HYPOTHESIS; The aim of the Diabetes Prevention Study is to assess the efficacy of an intensive diet-exercise programme in preventing or delaying Type II (non-insulin-dependent) diabetes mellitus in subjects with impaired glucose tolerance, to evaluate the effects of the intervention programme on cardiovascular risk factors and to assess the determinants for the progression to diabetes in persons with impaired glucose tolerance., Methods: A total of 523 overweight subjects with impaired glucose tolerance ascertained by two oral glucose tolerance tests were randomised to either a control or intervention group. The control subjects received general information at the start of the trial about the lifestyle changes necessary to prevent diabetes and about annual follow-up visits. The intervention subjects had seven sessions with a nutritionist during the first year and a visit every 3 months thereafter aimed at reducing weight, the intake of saturated fat and increasing the intake of dietary fibre. Intervention subjects were also guided individually to increase their physical activity., Results: During the first year, weight loss in the first 212 study subjects was 4.7 +/- 5.5 vs 0.9 +/- 4.1 kg in the intervention and control group, respectively (p < 0.001). The plasma glucose concentrations (fasting: 5.9 +/- 0.7 vs 6.4 +/- 0.8 mmol/l, p < 0.001; and 2-h 7.8 +/- 1.8 vs 8.5 +/- 2.3 mmol/l, p < 0.05) were significantly lower in the intervention group after the first year of intervention. Favourable changes were also found in blood pressure, serum lipids and anthropometric indices in the intervention group., Conclusion/interpretation: The interim results show the efficacy and feasibility of the lifestyle intervention programme.

Hexokinase II (HKII) catalyses a key step in glucose metabolism and can be regarded as a candidate gene for insulin resistance and type 2 (non-insulin-dependent) diabetes mellitus. We observed previously four amino acid substitutions among Finnish type 2 diabetic patients: Gln142His, Ala314Val; 0.9%, Arg353Cys; 2.7% and Arg775Gln; 2.7%. The Arg775Gln mutation was also observed in normal control subjects (2.1%) and the Gln142His substitution was found in both Type II diabetic and normal subjects with similar frequencies (approximately 20%). Since Gln at position 142, Ala at 314 and Arg at 775 are present in human and rat hexokinases and could be important for structure and function of the enzyme, we generated all four substitutions by site-directed mutagenesis and expressed them in E.coli. None of these substitutions had any effect on HKII catalytic activity, K(m) or Vmax for glucose values in vitro. Thus unless these substitutions have an impact on enzyme activity or regulation in vivo, it is unlikely that these substitutions contribute to the aetiology of Type II diabetes.

The polymorphisms in the uncoupling protein 1 (UCP1, A to G) and beta3-adrenergic receptor (beta3-AR, Trp64Arg) genes have been suggested to be associated with an increased tendency to gain weight. We investigated the frequency of the A to G polymorphism of the UCP1 gene and its effect on basal metabolic rate (BMR) among obese Finns. We also examined the effects of the simultaneous occurrence of the polymorphisms in the UCP1 and beta3-AR genes on BMR. Altogether 170 obese subjects (29 men, 141 women, BMI 34.7beta3.8 kg/m2, age 43+/-8 years, mean+/-SD) participated in the study. The A to G substitution of the UCP1 gene was verified by digestion of the PCR product with Bcl I. The frequency of the A to G polymorphism of the UCP1 gene in obese subjects did not differ significantly from the population-based control subjects (5 vs 1 % for homozygotes (GG) and 35 vs 42 % for heterozygotes (AG), p=0.077, for trend). BMR adjusted for lean body mass, age and sex (adjBMR) was similar among the three UCP1 gene genotypes of obese subjects (AA n=90, AG n=72 or GG n=8). However, the subjects with the polymorphisms in both UCP1 and beta3-AR genes (n=18) had a 79 kcal/day (95% CI 30-128) lower adjBMR than the subjects without these polymorphisms (n=76) (1551+/-77 vs 1629+/-141 kcal/day, p=0.002). Furthermore, adjBMR was 63 kcal/day (95 % CI 7-118 kcal/day) lower in the subjects with both polymorphisms (n=18) compared with the subjects (n=14) who had only the polymorphism in the beta3-AR gene (1551+/-77 vs 1613+/-76 kcal/day, p=0.028). The A to G polymorphism of the UCP1 gene did not have an independent effect on BMR, but its simultaneous existence with the Trp64Arg polymorphism of the beta3-AR gene resulted in more lowered BMR than the Trp64Arg polymorphism of beta3-AR gene alone.

Hexokinase II (HKII) plays an important role in facilitating glucose uptake by skeletal muscle, heart, and adipose tissue in response to insulin. We have cloned and sequenced the proximal promoter region of the human HKII gene, determined the transcription start sites and screened the 2.0 kb of the proximal 5' flanking region for variants in non-insulin-dependent diabetic patients and control subjects. We found three variants in this region, one in the 5' untranslated region (G-->C at +217) and two in the promoter region (T-->G at -1043 and G-->A at -1159). The allele frequencies of these variants did not differ between the diabetic and control subjects and these variants are not associated with insulin resistance. Various segments of the human HKII promoter were tested for driving expression of the luciferase reporter gene. The proximal 500 bp and 400 bp of the promoter were sufficient to drive maximal activity in adipocyte (3T3F442A) and myocyte (C2C12F3) cell lines, respectively. This region of the promoter is GC-rich and contains eight consensus binding sites for the transcription factor Sp-1, five for AP-2, two putative response elements for each of insulin and cyclic AMP. The proximal 175 bases of the promoter retained only 7-15% of maximal activity. Sequence elements located between positions -304 and -215 accounted for approximately 80% of the basal HKII promoter. In addition, the region between -215 and -184 contains a negative regulatory element for expression in 3T3F442A but not in C2C12F3 cells.

Impaired glycogen synthesis after insulin stimulation accounts for most of the insulin resistance in patients with non-insulin-dependent diabetes mellitus (NIDDM). The glycogen synthase gene (GYS1), which encodes the rate-limiting enzyme for glycogen synthesis, is a promising candidate gene for NIDDM. Therefore, we screened all 16 exons of this gene by single-strand conformation polymorphism analysis in 40 patients with NIDDM (age 67 +/- 2 years, body mass index 28.2 +/- 0.6 kg/m2) from Taipalsaari, eastern Finland. The Gly464Ser variant (exon 11) and a silent polymorphism TTC342TTT (exon 7) have been reported previously. In addition, we found a new variant Gln71His (exon 2) and a new amino acid polymorphism Met416Val (exon 10). An additional sample of 65 patients with NIDDM and 82 normoglycaemic men (age 54 +/- 1 years, body mass index 26.3 +/- 1.4 kg/m2) were screened. The allele frequency of the TTC342TTT silent substitution was 0.29 in both NIDDM and normoglycaemic subjects. The Gln71His and Gly464Ser variants were found in 1 (1%) and 3 (3%) subjects, respectively, of the 105 NIDDM patients and in none of the 82 normoglycaemic men. The Met416Val polymorphism was found in 16 (15%) of the 105 NIDDM patients and in 14 (17%) of the 82 control subjects (all heterozygous). The Met416Val polymorphism was not associated with insulin resistance in two groups of normoglycaemic subjects. In conclusion, the new Gln71His and Met416Val substitutions and other variants of the glycogen synthase gene are unlikely to make a major contribution to insulin resistance and NIDDM in diabetic patients from eastern Finland.