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Context Youth-onset type 2 diabetes is a disease of pubertal onset, associated with additional burden of pubertal insulin resistance on the β-cell. Objective Evaluate the impact of metformin treatment during puberty, a critical window of cardiometabolic change, on insulin sensitivity (Si) and compensatory β-cell response in youth with obesity. Setting Pediatric academic hospital clinical translational research center. Participants Healthy youth in early puberty [Tanner stage (T) 2-3] with normoglycemia and obesity (n = 44). Intervention Double-blinded placebo-control trial of metformin during puberty (until T5). Main Outcome Measures Insulin sensitivity (Si), insulin response [acute insulin response to glucose (AIRg)], and disposition index (DI), estimated from frequently sampled intravenous glucose tolerance testing; body fat (dual X-ray absorptiometry); and other laboratory parameters, collected at baseline, T4, and T5. Placebo-subtracted treatment effect was calculated using linear mixed models. Results At T5, metformin treatment, adjusting for sex, race, and baseline value, was associated with improved BMI z-score (−0.44 ± 0.16, P = 0.02), percentage body fat (%body fat; −3.4 ± 1.2%, P = 0.06), and waist circumference (−11.3 ± 3.2cm, P = 0.003). There were no significant treatment effects at T5 on Si or secretion: Si (0.85 ± 0.87 × 10−4/min−1/μIU/mL, P = 0.34), AIRg (−259 ± 386 μIU/mL, P = 0.51), or DI (508 ± 802 × 10−4/min−1, P = 0.53). High baseline DI predicted longitudinal decline in DI. Conclusions Two years of metformin treatment in obese youth during puberty improved BMI and body fat, but not Si or β-cell function. Of note, high DI in early puberty may be predictive of later decline in DI. Further studies are needed to develop strategies for preservation of β-cell function in youth at risk for type 2 diabetes.

Context Physiologic changes in glucose metabolism are well-described to occur during puberty. However, there are important gaps in understanding the interaction between obesity and the normal physiologic changes during puberty, as well as how these changes could contribute to the increased risk of comorbidities, such as type 2 diabetes and dyslipidemia, in youth with obesity. Objective The objective of this study was to compare longitudinal changes in insulin sensitivity (Si) and secretion during pubertal progression in youth with obesity versus those with normal weight. Design Longitudinal observational study evaluating youth from early puberty (Tanner [T]2-T3) until puberty completion (T5). Setting Pediatric academic hospital Clinical Translational Research Center. Participants Pubertal youth with normal weight (n = 47; 22 female, 25 male) and obesity (n = 37; 23 female, 14 male) Main Outcome Measures Si, insulin response (acute insulin response to glucose, AIRg) and disposition index (DI) by intravenous glucose tolerance test at baseline (T2-T3), T4, and T5 Results Youth with obesity had significantly lower Si and higher AIRg at each time point (P Conclusions Obesity significantly impacts Si during puberty, even at the earliest stages. However, in general, obese youth have adequate β-cell compensation for the significantly reduced Si of puberty. Future studies are needed to better predict the subset of youth who fail to maintain β-cell compensation during puberty.

Context Cardiovascular disease (CVD) is a major cause of mortality in adults with type 1 diabetes. Objective We prospectively evaluated CVD risk factors in a large, contemporary cohort of adults with type 1 diabetes living in the United States. Design Observational study of CVD and CVD risk factors over a median of 5.3 years. Setting The T1D Exchange clinic network. Patients Adults (age ≥ 18 years) with type 1 diabetes and without known CVD diagnosed before or at enrollment. Main Outcome Measure Associations between CVD risk factors and incident CVD were assessed by multivariable logistic regression. Results The study included 8,727 participants (53% female, 88% non-Hispanic white, median age 33 years [interquartile ratio {IQR} = 21, 48], type 1 diabetes duration 16 years [IQR = 9, 26]). At enrollment, median HbA1c was 7.6% (66 mmol/mol) (IQR = 6.9 [52], 8.6 [70]), 33% used a statin, and 37% used blood pressure medication. Over a mean follow-up of 4.6 years, 325 (3.7%) participants developed incident CVD. Ischemic heart disease was the most common CVD event. Increasing age, body mass index, HbA1c, presence of hypertension and dyslipidemia, increasing duration of diabetes, and diabetic nephropathy were associated with increased risk for CVD. There were no significant gender differences in CVD risk. Conclusion HbA1c, hypertension, dyslipidemia and diabetic nephropathy are important risk factors for CVD in adults with type 1 diabetes. A longer follow-up is likely required to assess the impact of other traditional CVD risk factors on incident CVD in the current era.

Context Polycystic ovary syndrome (PCOS) is a common endocrine disorder and is associated with metabolic syndrome (MS). Development of MS in PCOS is likely multifactorial and may relate to poor sleep. Objective The objective of this research is to investigate differences in objective markers of sleep in adolescents with obesity and PCOS with and without MS. We also aimed to examine the relationships between markers of sleep with MS markers. Design A cross-sectional study was conducted. Participants Participants included adolescents with PCOS and obesity with MS (N = 30) or without MS (N = 36). Outcome Measures Hormone and metabolic measurements, abdominal magnetic resonance imaging for hepatic fat fraction, actigraphy to estimate sleep, and overnight polysomnography (PSG). Results Adolescents with obesity and PCOS who also had MS had significantly worse sleep-disordered breathing including higher apnea-hypopnea index (AHI, P = .02) and arousal index (P = .01) compared to those without MS. Actigraphy showed no differences in habitual patterns of sleep behaviors including duration, timing, or efficiency between groups. However, a greater number of poor sleep health behaviors was associated with greater number of MS components (P = .04). Higher AHI correlated with higher triglycerides (TG) (r = 0.49, P = .02), and poorer sleep efficiency correlated with higher percentage of liver fat (r = –0.40, P = .01), waist circumference (r = –0.46, P Conclusions Among girls with PCOS and obesity, sleep-disordered breathing was more prevalent in those with MS, and poor sleep behaviors were associated with metabolic dysfunction and more MS symptoms. Sleep health should be included in the assessment of adolescents with PCOS and obesity.

Context As many as 1.8% of adolescents identify as transgender and many more seek care, yet the impact of gender-affirming hormone therapy (GAHT) on cardiometabolic health is unknown. Objective To determine insulin sensitivity and body composition among transgender females (TF) and males (TM) on estradiol or testosterone, compared with cisgender females (CF) and males (CM). Design Pilot, cross-sectional study conducted from 2016–2018. Setting Academic regional transgender referral center. Participants Transgender adolescents on either testosterone or estradiol for at least 3 months were recruited. Nineteen TM were matched to 19 CM and 42 CF on pubertal stage and body mass index (BMI). Eleven TF were matched to 23 CF and 13 TF to 24 CM on age and BMI. Main Outcome Measures 1/[fasting insulin] and body composition (dual-energy x-ray absorptiometry). Results Total body fat was lower in TM than CF mean ± SD: (29% ± 7% vs 33% ± 7%; P = 0.002) and higher than in CM (28% ± 7% vs 24% ± 9%; P = 0.047). TM had higher lean mass than CF (68% ± 7% vs 64% ± 7%, P = 0.002) and lower than CM (69% ± 7% vs 73% ± 8%; P = 0.029). Insulin sensitivity was not different between the groups. TF had lower body fat than CF (31% ± 7% vs 35% ± 8%; P = 0.033) and higher than CM (28% ± 6% vs 20% ± 10%; P = 0.001). TF had higher lean mass than CF (66% ± 6% vs 62% ± 7%; P = 0.032) and lower than CM (69% ± 5% vs 77% ± 9%; P = 0.001). TF were more insulin resistant than CM (0.078 ± 0.025 vs 0.142 ± 0.064 mL/μU; P = 0.011). Conclusions Transgender adolescents on GAHT have significant differences in body composition compared with cisgender controls, with a body composition intermediate between BMI-matched CMs and CFs. These changes in body composition may have consequences for the cardiometabolic health of transgender adolescents. ClinicalTrials.gov NCT02550431

Context Type 1 diabetes in adolescence is characterized by insulin deficiency and insulin resistance (IR), both thought to increase cardiovascular disease risk. We previously demonstrated that adolescents with type 1 diabetes have adipose, hepatic, and muscle IR, and that metformin lowers daily insulin dose, suggesting improved IR. However, whether metformin improves IR in muscle, hepatic, or adipose tissues in type 1 diabetes was unknown. Objective Measure peripheral, hepatic, and adipose insulin sensitivity before and after metformin or placebo therapy in youth with obesity with type 1 diabetes. Design Double-blind, placebo-controlled clinical trial. Setting Multi-center at eight sites of the T1D Exchange Clinic Network. Participants A subset of 12- to 19-year-olds with type 1 diabetes (inclusion criteria: body mass index ≥85th percentile, HbA1c 7.5% to 9.9%, insulin dosing ≥0.8 U/kg/d) from a larger trial (NCT02045290) were enrolled. Intervention Participants were randomized to 3 months of metformin (N = 19) or placebo (N = 18) and underwent a three-phase hyperinsulinemic euglycemic clamp with glucose and glycerol isotope tracers to assess tissue-specific IR before and after treatment. Main outcome measures Peripheral insulin sensitivity, endogenous glucose release, rate of lipolysis. Results Between-group differences in change in insulin sensitivity favored metformin regarding whole-body IR [change in glucose infusion rate 1.3 (0.1, 2.4) mg/kg/min, P = 0.03] and peripheral IR [change in metabolic clearance rate 0.923 (-0.002, 1.867) dL/kg/min, P = 0.05]. Metformin did not impact insulin suppression of endogenous glucose release (P = 0.12). Adipose IR was not assessable with traditional methods in this highly IR population. Conclusions Metformin appears to improve whole-body and peripheral IR in youth who are overweight/obese with type 1 diabetes.

Context To our knowledge, circadian rhythms have not been examined in girls with polycystic ovarian syndrome (PCOS), despite the typical delayed circadian timing of adolescence, which is an emerging link between circadian health and insulin sensitivity (SI), and decreased SI in PCOS. Objective To examine differences in the circadian melatonin rhythm between obese adolescent girls with PCOS and control subjects, and evaluate relationships between circadian variables and SI. Design Cross-sectional study. Participants Obese adolescent girls with PCOS (n = 59) or without PCOS (n = 33). Outcome Measures Estimated sleep duration and timing from home actigraphy monitoring, in-laboratory hourly sampled dim-light, salivary-melatonin and fasting hormone analysis. Results All participants obtained insufficient sleep. Girls with PCOS had later clock-hour of melatonin offset, later melatonin offset relative to sleep timing, and longer duration of melatonin secretion than control subjects. A later melatonin offset after wake time (i.e., morning wakefulness occurring during the biological night) was associated with higher serum free testosterone levels and worse SI regardless of group. Analyses remained significant after controlling for daytime sleepiness and sleep-disordered breathing. Conclusion Circadian misalignment in girls with PCOS is characterized by later melatonin offset relative to clock time and sleep timing. Morning circadian misalignment was associated with metabolic dysregulation in girls with PCOS and obesity. Clinical care of girls with PCOS and obesity would benefit from assessment of sleep and circadian health. Additional research is needed to understand mechanisms underlying the relationship between morning circadian misalignment and SI in this population.

Context: Obesity, insulin resistance (IR), and diabetes are increasing in youth, especially in girls. IR is associated with muscle mitochondrial dysfunction in youth and adults with diabetes. However, it is unknown whether this relationship is present in youth prior to development of diabetes. Objective: Assess IR and mitochondrial function, including sex differences, in nondiabetic youth. Design: Cross-sectional study of youth in the Exploring Perinatal Outcomes among Children, Resistance to InSulin in Type 1 And Type 2 diabetes, and Androgens and Insulin Resistance Study cohorts. Setting: Academic medical university. Participants: Two hundred seventy-five youth, 13 to 19 years old [43% males: 17.1 (16.52, 17.63) years, body mass index z-score (BMI-Z) 0.36, 64.7% Tanner 5; 57% females: 17.2 (16.43, 17.67) years, BMI-Z 0.72, 78.9% Tanner 5]. Interventions: Fasting laboratories, oral glucose tolerance test, and 31P magnetic resonance spectroscopy. Main Outcome Measures: IR [triglyceride:high-density lipoprotein (HDL) ratio, Matsuda index, and homeostasis model for insulin resistance (HOMA-IR)] and muscle mitochondrial function (adenosine 5′-diphosphate time constant and oxidative phosphorylation rate). Results: Compared with males, females were more insulin resistant, with higher triglyceride:HDL ratio [1.95 (1.30, 2.79) vs 1.69 (1.21, 2.23), P = 0.042], HOMA-IR [3.18 (2.42, 4.39) vs 2.76 (2.02, 4.08), P = 0.035], and fasting free fatty acids (FFAs) and lower Matsuda score [3.98 (2.71, 5.96) vs 5.39 (3.43, 7.57), P < 0.001]. After adjustment for the higher BMI and Tanner stage and lower physical activity levels seen in females, there were no sex differences in mitochondrial function nor in any IR measure except FFAs. We did not find an association between measures of IR and mitochondrial function. Conclusions: The greater IR seen in adolescent girls vs boys is mostly explained by differences in BMI and physical activity. Mitochondrial function does not appear to be related to IR in a large cohort of nondiabetic youth.

Insulin resistance (IR) and type 2 diabetes are increasing, particularly in Hispanic (H) vs non-Hispanic White (NHW) populations. Adiponectin has a known role in IR, and therefore, understanding ethnic and sex-specific behavior of adiponectin across the lifespan is of clinical significance.To compare ethnic and sex differences in adiponectin, independent of body mass index, across the lifespan and relationship to IR.Cross-sectional.Primary care, referral center.A total of 187 NHW and 117 H participants (8-57 y) without diabetes. Life stage: pre-/early puberty (Tanner 1/2), midpubertal (Tanner 3/4), late pubertal (Tanner 5,21 years), and adult (Tanner 5, ≥21).None.Fasting adiponectin, insulin, glucose, and revised homeostatic model assessment of insulin resistance.Adiponectin was significantly inversely correlated with revised homeostatic model assessment of insulin resistance. Regarding puberty, adiponectin trended downward in late puberty, but only males were significantly lower in adulthood. By sex, adiponectin was lower in adult males vs females of both ethnicities. Regarding ethnicity, H adults of both sexes had lower adiponectin than NHW adults. Of note, in NHW females, adiponectin trended highest in adulthood, whereas in H females, adiponectin fell in late puberty and remained lower in adulthood.Adiponectin inversely correlated with IR, trended down in late puberty, and was lowest in adult males. H adults of both sexes had lower adiponectin than NHW adults, and H females followed a more "male pattern," lacking the rebound in adiponectin seen in NHW females after puberty. These data suggest that adiponectin, independent of body mass index, may relate to the greater cardiometabolic risk seen in H populations and in particular H females.

The optimal screening test for diabetes and prediabetes in obese youth is controversial.We examined whether glycosylated hemoglobin (HbA1c) or the oral glucose tolerance test (OGTT) is a better predictor of free-living glycemia as measured by continuous glucose monitoring (CGM).This was a cross-sectional study of youth 10-18 years old, body mass index (BMI) 85th percentile or greater, with diabetes risk factors.Participants (n = 118) with BMI 85th percentile or greater, not on medications for glucose management, were recruited from primary care and pediatric endocrinology clinics around Denver, Colorado.HbA1c, fasting plasma glucose, and 2-hour glucose were collected and all participants wore a blinded CGM for 72 hours.CGM outcomes were determined and descriptive statistics calculated. Performance characteristics at current American Diabetes Association cutpoints were compared with CGM outcomes.CGM data were successfully collected on 98 obese youth. Those with prediabetes had significantly higher average glucose, area under the curve (AUC), peak glucose, and time greater than 120 and greater than 140 mg/dL (P.01) on CGM than youth with normal HbA1c or OGTT. HbA1c had a greater magnitude of correlation to CGM average glucose, AUC, and minimum glucose; 2-hour glucose had a greater magnitude of correlation to CGM SD, peak glucose, and time greater than 140 and greater than 200 mg/dL. However, there were no overall differences in the strength comparisons between 2-hour glucose and HbA1c correlations to CGM outcomes.In obese youth, HbA1c and 2-hour glucose performed equally well at predicting free-living glycemia on CGM, suggesting that both are valid tests for dysglycemia screening.

Context: Cardiovascular disease is the major cause of death in adults with diabetes, yet little is specifically known about the effects of type 1 diabetes (T1D) on cardiovascular outcomes in youth. Although insulin resistance (IR) likely contributes to exercise and cardiovascular dysfunction in T2D, IR is not typically considered a contributor in T1D. Objective: We hypothesized that cardiopulmonary fitness would be reduced in T1D youth in association with IR and cardiovascular dysfunction. Design and Participants: This cross-sectional study at an academic hospital included 12 T1D adolescents compared with 12 nondiabetic controls, similar in age, pubertal stage, activity level, and body mass index. Outcome Measures: Cardiopulmonary fitness was measured by peak oxygen consumption (VO2peak) and oxygen uptake kinetics (VO2kinetics), IR by hyperinsulinemic clamp, cardiac function by echocardiography, vascular function by venous occlusion plethysmography, intramyocellular lipid by magnetic resonance spectroscopy, and body composition by dual-energy x-ray absorptiometry. Results: T1D adolescents had significantly decreased VO2peak, peak work rate, and insulin sensitivity compared with nondiabetic adolescents. T1D youth also had reduced vascular reactivity and evidence of diastolic dysfunction and left ventricular hypertrophy. Despite their IR and reduced cardiovascular fitness, T1D youth had paradoxically normal intramyocellular lipid, waist to hip ratio, and serum lipids and high adiponectin levels. In multivariate analysis, IR primarily, and forearm blood flow secondarily, independently predicted VO2peak. Conclusions: T1D youth demonstrated IR, impaired functional exercise capacity and cardiovascular dysfunction. The phenotype of IR in T1D youth was unique, suggesting a pathophysiology that is different from T2D, yet may adversely affect long-term cardiovascular outcomes.

The incidence of pediatric type 2 diabetes (T2D) is rising, with unclear effects on the cardiovascular system. Cardiopulmonary fitness, a marker of morbidity and mortality, is abnormal in adults with T2D, yet the mechanisms are incompletely understood.We hypothesized that cardiopulmonary fitness would be reduced in youth with T2D in association with insulin resistance (IR) and cardiovascular dysfunction.We conducted a cross-sectional study at an academic hospital that included 14 adolescents (age range, 12-19 yr) with T2D, 13 equally obese adolescents and 12 lean adolescents similar in age, pubertal stage, and activity level.Cardiopulmonary fitness was measured by peak oxygen consumption (VO(2)peak) and oxygen uptake kinetics (VO(2)kinetics), IR by hyperinsulinemic clamp, cardiac function by echocardiography, vascular function by venous occlusion plethysmography, body composition by dual-energy x-ray absorptiometry, intramyocellular lipid by magnetic resonance spectroscopy, and inflammation by serum markers.Adolescents with T2D had significantly decreased VO(2)peak and insulin sensitivity, and increased soleus intramyocellular lipid, C-reactive protein, and IL-6 compared to obese or lean adolescents. Adolescents with T2D also had significantly prolonged VO(2)kinetics, decreased work rate, vascular reactivity, and adiponectin, and increased left ventricular mass and fatty acids compared to lean adolescents. In multivariate linear regression analysis, IR primarily, and fasting free fatty acids and forearm blood flow secondarily, were significant independent predictors of VO(2)peak.Given the strong relationship between decreased cardiopulmonary fitness and increased mortality, these findings in children are especially concerning and represent early signs of impaired cardiac function.