Single-leg exercise training augments in vivo skeletal muscle oxidative flux and vascular content and function in adults with type 2 diabetes.

KEY POINTS: People with type 2 diabetes (T2D) have impaired skeletal muscle oxidative flux due to limited oxygen delivery. In the current study, this impairment in oxidative flux in people with T2D was abrogated with a single-leg exercise training protocol. Additionally, single-leg exercise training increased skeletal muscle CD31 content, calf blood flow and state 4 mitochondrial respiration in all participants. ABSTRACT: Cardiorespiratory fitness is impaired in type 2 diabetes (T2D), conferring significant cardiovascular risk in this population; interventions are needed. Previously, we reported that a T2D-associated decrement in skeletal muscle oxidative flux is ameliorated with acute use of supplemental oxygen, suggesting that skeletal muscle oxygenation is rate-limiting to in vivo mitochondrial oxidative flux during exercise in T2D. We hypothesized that single-leg exercise training (SLET) would improve the T2D-specific impairment in in vivo mitochondrial oxidative flux during exercise. Adults with (n = 19) and without T2D (n = 22) with similar body mass indexes and levels of physical activity participated in two weeks of SLET. Following SLET, in vivo oxidative flux measured by 31 P-MRS increased in participants with T2D, but not people without T2D, measured by the increase in initial phosphocreatine synthesis (P = 0.0455 for the group × exercise interaction) and maximum rate of oxidative ATP synthesis (P = 0.0286 for the interaction). Additionally, oxidative phosphorylation increased in all participants with SLET (P = 0.0209). After SLET, there was no effect of supplemental oxygen on any of the in vivo oxidative flux measurements in either group (P > 0.02), consistent with resolution of the T2D-associated oxygen limitation previously observed at baseline in subjects with T2D. State 4 mitochondrial respiration also improved in muscle fibres ex vivo. Skeletal muscle vasculature content and calf blood flow increased in all participants with SLET (P < 0.0040); oxygen extraction in the calf increased only in T2D (P = 0.0461). SLET resolves the T2D-associated impairment of skeletal muscle in vivo mitochondrial oxidative flux potentially through improved effective blood flow/oxygen delivery.

Precision and accuracy of hyperglycemic clamps in a multicenter study.

Application of glucose clamp methodologies in multicenter studies brings challenges for standardization. The Restoring Insulin Secretion (RISE) Consortium implemented a hyperglycemic clamp protocol across seven centers using a combination of technical and management approaches to achieve standardization. Two-stage hyperglycemic clamps with glucose targets of 200 mg/dL and >450 mg/dL were performed utilizing a centralized spreadsheet-based algorithm that guided dextrose infusion rates using bedside plasma glucose measurements. Clamp operators received initial and repeated training with ongoing feedback based on surveillance of clamp performance. The precision and accuracy of the achieved stage-specific glucose targets were evaluated, including differences by study center. We also evaluated robustness of the method to baseline physiologic differences and on-study treatment effects. The RISE approach produced high overall precision (3%-9% variance in achieved plasma glucose from target at various times across the procedure) and accuracy (SD < 10% overall). Statistically significant but numerically small differences in achieved target glucose concentrations were observed across study centers, within the magnitude of the observed technical variability. Variation of the achieved target glucose over time in placebo-treated individuals was low (<3% variation), and the method was robust to differences in baseline physiology (youth vs. adult, IGT vs. diabetes status) and differences in physiology induced by study treatments. The RISE approach to standardization of the hyperglycemic clamp methodology across multiple study centers produced technically excellent standardization of achieved glucose concentrations. This approach provides a reliable method for implementing glucose clamp methodology across multiple study centers.NEW & NOTEWORTHY The Restoring Insulin Secretion (RISE) study centers undertook hyperglycemic clamps using a simplified methodology and a decision guidance algorithm implemented in an easy-to-use spreadsheet. This approach, combined with active management including ongoing central data surveillance and routine feedback to study centers, produced technically excellent standardization of achieved glucose concentrations on repeat studies within and across study centers.

Lean NAFLD: an underrecognized and challenging disorder in medicine.

Classically, Non-Alcoholic Fatty Liver Disease (NAFLD) has been thought to be driven by excessive weight gain and obesity. The overall greater awareness of this disorder has led to its recognition in patients with normal body mass index (BMI). Ongoing research has helped to better understand potential causes of Lean NAFLD, the risks for more advanced disease, and potential therapies. Here we review the recent literature on prevalence, risk factors, severity of disease, and potential therapeutic interventions.

Results from the Effects of MEtformin on cardiovasculaR function in AdoLescents with type 1 Diabetes (EMERALD) study: A brief report of kidney and inflammatory outcomes.

Youth with type 1 diabetes (T1D) demonstrate insulin resistance, independently of glycaemia, when compared to normoglycaemic peers. Insulin resistance increases the risk of cardiovascular disease and diabetic kidney disease, factors also associated with systemic inflammation. We evaluated the effect of metformin on markers of inflammation and diabetic kidney disease in adolescents with T1D. EMERALD, a double-blind, randomized, placebo-controlled trial of 3 months of metformin in 48 participants aged 12-21 years with T1D, included baseline and follow-up assessments of serum creatinine and cystatin C to estimate glomerular filtration rate (eGFR), aspartate aminotransferase, alanine aminotransferase, high-sensitivity C-reactive protein, white blood count, platelets, adiponectin, leptin, and urine albumin: creatinine ratio (UACR). Metformin was associated with a 13.9 mL/min/1.73 m2 (95% confidence interval 4.7-23.1 mL/min/1.73 m2 ) increase in estimated GFR by serum creatinine versus placebo (P ≤ 0.01), with a significant difference remaining after multivariable adjustments (P = 0.03). Whereas eGFR measured by serum creatinine increased significantly after metformin treatment, no differences were observed in cystatin C, UACR, or systemic inflammatory markers. Additional studies with directly measured GFR in response to metformin in T1D are needed.

Development of type 2 diabetes in adolescent girls with polycystic ovary syndrome and obesity.

OBJECTIVE: Adult women with polycystic ovary syndrome (PCOS) and obesity have an 8-fold increased risk of developing type 2 diabetes (T2D). Our goal was to determine the incidence and risk factors for T2D in adolescents with PCOS and obesity. RESEARCH DESIGN AND METHODS: Retrospective chart review of girls aged 11-21 years with confirmed PCOS (oligomenorrhea and hyperandrogenism) diagnosis between July 2013 and Aug 2018 and at least one follow-up visit and BMI >85%ile. T2D incidence, defined with an HbA1c ≥6.5%, was calculated. A nested case-control study with 1:3 matching by race, ethnicity, and BMI was performed to determine predictors of T2D diagnosis. RESULTS: Four hundred ninety-three patients with PCOS (age 15.6 ± 1.9 years, BMI 36.2 ± 6.3 kg/m2 ) were identified with a follow-up of 1018 person-years. Twenty-three developed T2D (incidence 22.6/1000 person-years) with diagnosis a median of 1.8 years (2 months-5.5 years) after PCOS diagnosis. T2D risk was higher in girls with a prediabetes HbA1c (5.7%-6.4%) (HR 14.6 [4.8-44.5]) and among Hispanic girls with an elevated HbA1c and alanine aminotransferase (HR 19.0 [3.7-97.2]) at the time of PCOS diagnosis. In the 1:3 matched cohort, T2D risk was 18.7 times higher (OR 18.66 [2.27-153.24]) for every 0.1% increase in HbA1c at the time of PCOS diagnoses. CONCLUSIONS: Girls with PCOS and obesity have an 18-fold increase in T2D incidence compared to published rates in non-PCOS youth. Hispanic girls with elevated HbA1c and ALT are at particular risk. Due to the morbidity associated with youth onset T2D, these findings argue for better screening and prevention approaches in this population.

Good agreement between hyperinsulinemic-euglycemic clamp and 2 hours oral minimal model assessed insulin sensitivity in adolescents.

BACKGROUND/OBJECTIVE: Rates of dysglycemia are increasing in youth, secondary to obesity and decreased insulin sensitivity (IS) in puberty. The oral minimal model (OMM) has been developed in order to measure IS using an easy oral glucose load, such as an oral glucose tolerance test (OGTT), instead of an hyperinsulinemic-euglycemic clamp (HE-clamp), a more invasive and time-consuming procedure. However, this model, following a standard 2 hour- OGTT has never been validated in youth, a population known for a different physiologic response to OGTT than adults. Thus, we compared IS measurements obtained from OMM following a 2-hour OGTT to HE-clamp and isotope tracer-assessed tissue IS in adolescents. We also compared the liver/muscle-specific IS from HE-clamp with other liver/muscle-specific IS surrogates following an OGTT previously validated in adults. METHODS: Secondary analysis of a cross-sectional study. Adolescent girls with (n = 26) and without (n = 7) polycystic ovary syndrome (PCOS) (14.6 ± 1.7 years; BMI percentile 23.3%-98.2%) underwent a 2-hour 75 g OGTT and a 4-phase HE-clamp. OMM IS (Si), dynamic Si (Sid ) and other OGTT-derived muscle and liver IS indices were correlated with HE-clamp tissue-specific IS. RESULTS: OMM Si and Sid correlated with HE-clamp-measured peripheral IS (r = 0.64, P <.0001 and r = 0.73; P <.0001, respectively) and the correlation coefficient trended higher than the Matsuda index (r = 0.59; P =.003). The other tissue-specific indices were poorly correlated with their HE-clamp measurements. CONCLUSION: In adolescent girls, the 2-hour OMM provided the best estimate of peripheral IS. Additional surrogates for hepatic IS are needed for youth.

ß-cells in youth with impaired glucose tolerance or early type 2 diabetes secrete more insulin and are more responsive than in adults.

OBJECTIVE: Glycemic control deteriorates more rapidly in youth vs adults. We compared model-derived measures of ß-cell function between youth and adults with either impaired glucose tolerance (IGT) or type 2 diabetes to determine if a ß-cell defect differentiates these age groups. METHODS: This is a cross-sectional analysis of baseline data from the Restoring Insulin Secretion (RISE) Study. Youth (54 Y-IGT, 33 Y-D) and adults (250 A-IGT, 104 A-D) underwent 3-hour oral glucose tolerance tests for modeling of insulin secretion rates (ISRs), glucose sensitivity, and rate sensitivity. Insulin sensitivity was quantified as the glucose infusion rate/insulin (M/I) from a hyperglycemic clamp. RESULTS: Youth had lower insulin sensitivity despite similar body mass index. Analyses were adjusted for insulin sensitivity. Youth had higher basal ISRs (Y-IGT 200 ± 161 vs A-IGT 152 ± 74, P < .001; Y-D 245 ± 2.5 vs A-D 168 ± 115 pmol/min/m2 , P = .007) and total ISRs (Y-IGT 124 ± 86 vs A-IGT 98 ± 39, P < .001; Y-D 116 ± 110 vs A-D 97 ± 62 nmol/m2 , P = .002). Within IGT, glucose sensitivity (Y-IGT 140 ± 153 vs A-IGT 112 ± 70 pmol/min/m2 /mM, P = .004) and rate sensitivity (median[interquartile range]:Y-IGT 2271[1611, 3222] vs A-IGT 1164[685, 1565] pmol/m2 /mM, P < .001) were higher in youth, but not different by age group within diabetes. CONCLUSIONS: Model-derived measures of ß-cell function provide additional insight into the pathophysiology of type 2 diabetes in youth with higher ISRs and ß-cell secretion more responsive to glucose in youth relative to adults even after adjusting for differences in insulin sensitivity. It is unknown whether these findings in youth reflect ß-cells that are healthier or whether this is a defect that contributes to more rapid loss of function.

Sleep & Circadian Health are Associated with Mood & Behavior in Adolescents with Overweight/Obesity.

OBJECTIVE/BACKGROUND: Rates of overweight/obesity and insufficient/delayed sleep are high among adolescents and are also unique risk factors for mood/behavior difficulties. This study aimed to evaluate relationships between sleep/circadian health and mood/behavior in a cohort of adolescents with overweight/obesity. PARTICIPANTS: Twenty-two adolescents (16.4 ± 1.1 years) with overweight/obesity attending high school completed in the study. METHODS: Participants completed one week of home sleep monitoring (actigraphy), questionnaires assessing chronotype (diurnal preference; Morningness/Eveningness Scale for Children) and mood/behavior (Strengths & Difficulties Questionnaire), and had in-laboratory salivary melatonin sampling on a Thursday or Friday during the academic year. RESULTS: Linear regressions revealed later weekday bedtime and shorter weekday time in bed and sleep duration were associated with worse mood/behavior scores. Shorter duration of melatonin secretion and greater "eveningness" were also associated with worse mood/behavior scores. CONCLUSIONS: Short and late sleep, shorter melatonin secretion, and eveningness chronotype are associated with worse mood/behavior symptoms in a cohort of adolescents with overweight/obesity. Clinicians should assess for both sleep and mood/behavior symptoms and further research is needed to evaluate the impact of improved sleep on mood/behavior in adolescents with overweight/obesity.

Metformin Improves Insulin Sensitivity and Vascular Health in Youth With Type 1 Diabetes Mellitus.

BACKGROUND: Cardiovascular disease is the leading cause of mortality in type 1 diabetes mellitus (T1DM) and relates strongly to insulin resistance (IR). Lean and obese adolescents with T1DM have marked IR. Metformin improves surrogate markers of IR in T1DM, but its effect on directly measured IR and vascular health in youth with T1DM is unclear. We hypothesized that adolescents with T1DM have impaired vascular function and that metformin improves this IR and vascular dysfunction. METHODS: Adolescents with T1DM and control participants underwent magnetic resonance imaging of the ascending (AA) and descending aorta to assess pulse wave velocity, relative area change, and maximal (WSSMAX) and time-averaged (WSSTA) wall shear stress. Participants with T1DM also underwent assessment of carotid intima-media thickness by ultrasound, brachial distensibility by DynaPulse, fat and lean mass by dual-energy x-ray absorptiometry, fasting laboratories after overnight glycemic control, and insulin sensitivity by hyperinsulinemic-euglycemic clamp (glucose infusion rate/insulin). Adolescents with T1DM were randomized 1:1 to 3 months of 2000 mg metformin or placebo daily, after which baseline measures were repeated. RESULTS: Forty-eight adolescents with T1DM who were 12 to 21 years of age (40% body mass index [BMI] ≥90th percentile; 56% female) and 24 nondiabetic control participants of similar age, BMI, and sex distribution were enrolled. Adolescents with T1DM demonstrated impaired aortic health compared with control participants, including elevated AA and descending aorta pulse wave velocity, reduced AA and descending aorta relative area change, and elevated AA and descending aorta WSSMAX and WSSTA. Adolescents with T1DM in the metformin versus placebo group had improved glucose infusion rate/insulin (12.2±3.2 [mg·kg-1·min-1]/µIU/µL versus -2.4±3.6 [mg·kg-1·min-1]/µIU/µL, P=0.005; 18.6±4.8 [mg·lean kg-1·min-1]/µIU/µL versus -3.4±5.6 [mg·lean kg-1·min-1]/µIU/µL, P=0.005) and reduced weight (-0.5±0.5 kg versus 1.6±0.5 kg; P=0.004), BMI (-0.2±0.15 kg/m2 versus 0.4±0.15 kg/m2; P=0.005), and fat mass (-0.7±0.3 kg versus 0.6±0.4 kg; P=0.01). Glucose infusion rate/insulin also improved in normal-weight participants (11.8±4.4 [mg·kg-1·min-1]/µIU/µL versus -4.5±4.4 [mg·kg-1·min-1]/µIU/µL, P=0.02; 17.6±6.7 [mg·lean kg-1·min-1]/µIU/µL versus -7.0±6.7 [mg·lean kg-1·min-1]/µIU/µL, P=0.02). The metformin group had reduced AA WSSMAX (-0.3±0.4 dyne/cm2 versus 1.5±0.5 dyne/cm2; P=0.03), AA pulse wave velocity (-1.1±1.20 m/s versus 4.1±1.6 m/s; P=0.04), and far-wall diastolic carotid intima-media thickness (-0.04±0.01 mm versus -0.00±0.01 mm; P=0.049) versus placebo. CONCLUSIONS: Adolescents with T1DM demonstrate IR and impaired vascular health compared with control participants. Metformin improves IR, regardless of baseline BMI, and BMI, weight, fat mass, insulin dose, and aortic and carotid health in adolescents with T1DM. Metformin may hold promise as a cardioprotective intervention in T1DM. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov . Unique identifier: NCT01808690.

Amino acid and fatty acid metabolomic profile during fasting and hyperinsulinemia in girls with polycystic ovarian syndrome.

Polycystic ovarian syndrome (PCOS) is associated with insulin resistance (IR) and altered muscle mitochondrial oxidative phosphorylation. IR in adults with obesity and diabetes is associated with changes in amino acid, free fatty acid (FFA), and mitochondrial acylcarnitine (AC) metabolism. We sought to determine whether these metabolites are associated with IR and/or androgens in youth-onset PCOS. We enrolled obese girls with PCOS [ n = 15, 14.5 yr (SD 1.6), %BMI 98.5 (SD 1.0)] and without PCOS [ n = 6, 13.2 yr (SD 1.2), %BMI 98.0 (SD 1.1)]. Insulin sensitivity was assessed by hyperinsulinemic euglycemic clamp. Untargeted metabolomics of plasma was performed while fasting and during hyperinsulinemia. Fasting arginine, glutamine, histidine, lysine, phenylalanine, and tyrosine were higher ( P < 0.04 for all but P < 0.001 for valine), as were glutamine and histidine during hyperinsulinemia ( P < 0.03). Higher valine during hyperinsulinemia was associated with IR ( r = 0.59, P = 0.006). Surprisingly, end-clamp AC C4 was lower in PCOS, and lower C4 was associated with IR ( r = -0.44, P = 0.04). End-clamp FFAs of C14:0, C16:1, and C18:1 were higher in PCOS girls, and C16:1 and C18:1 strongly associated with IR ( r = 0.73 and 0.53, P < 0.01). Free androgen index related negatively to short-, medium-, and long-chain AC ( r = -0.41 to -0.71, P < 0.01) but not FFA or amino acids. Obese girls with PCOS have a distinct metabolic signature during fasting and hyperinsulinemia. As in diabetes, IR related to valine and FFAs, with an unexpected relationship with AC C4, suggesting unique metabolism in obese girls with PCOS.

Youth with type 2 diabetes have hepatic, peripheral, and adipose insulin resistance.

Adolescents with type 2 diabetes (T2D) have severe insulin resistance (IR) secondary to obesity, genetics, and puberty, and IR predicts metabolic comorbidities. Adults with T2D have multitissue IR, which has guided therapeutic developments, but this is not established in youth. We sought to assess adipose, hepatic, and peripheral insulin sensitivity in adolescents with and without T2D. Twenty-seven youth with T2D [age: 15.6 ± 0.4 yr; female: 78%; body mass index (BMI) percentile: 96.1 (52.6, 95.9), late puberty; hemoglobin A1c (HbA1c) 7.3% (6.2, 10.1)] and 21 controls of similar BMI, pubertal stage, and habitual activity were enrolled. Insulin action was measured with a four-phase hyperinsulinemic-euglycemic clamp (basal, 10, 16, and 80 mU·m-2·min-1 for studying adipose, hepatic, and peripheral IR, respectively) with glucose and glycerol isotope tracers. Total fat mass, fat-free mass, liver fat fraction, and visceral fat were measured with dual-energy x-ray absorptiometry (DXA) and MRI, respectively. Free fatty acids (FFAs), lipid profile, and inflammatory markers were also measured. Adolescents with T2D had higher lipolysis ( P = 0.012), endogenous glucose production ( P < 0.0001), and lower glucose clearance ( P = 0.002) during hyperinsulinemia than controls. In T2D, peripheral IR positively correlated to FFA ( P < 0.001), inflammatory markers, visceral ( P = 0.004) and hepatic fat ( P = 0.007); hepatic IR correlated with central obesity ( P = 0.004) and adipose IR ( P = 0.003). Youth with T2D have profound multitissue IR compared with BMI-equivalent youth without T2D. The development of multitissue interactions appears crucial to the pathogenesis of T2D. Therapeutic targets on multitissue IR may be of benefit, deserving of further research.

Too Late and Not Enough: School Year Sleep Duration, Timing, and Circadian Misalignment Are Associated with Reduced Insulin Sensitivity in Adolescents with Overweight/Obesity.

OBJECTIVES: To examine the relationship between insulin resistance (IR) and sleep/circadian health in overweight/obese adolescents. We hypothesized that insufficient and delayed sleep would be associated with IR in this population. STUDY DESIGN: Thirty-one adolescents (mean age, 16.0 ± 1.4 years; 77% female) with body mass index ≥90th percentile for age/sex were recruited from outpatient clinics at a children's hospital. Participants underwent 1 week of objective home sleep monitoring with wrist actigraphy during the academic year. A 3-hour oral glucose tolerance test was conducted, followed by in-laboratory salivary dim-light melatonin sampling every 30-60 minutes from 5 p.m. to noon the next day. Regression analyses between sleep and circadian variables with IR were examined. RESULTS: Longer sleep time and time in bed on weekends and weekdays and earlier weekday bedtime were significantly associated with better insulin sensitivity. Participants who obtained less than the median duration of sleep per night (6.6 hours) had evidence of IR with compensatory insulin secretion compared with those obtaining ≥6.6 hours of sleep. A wider phase angle between bedtime and melatonin onset, indicating a later circadian timing of sleep onset, was significantly associated with IR. CONCLUSIONS: Short sleep duration, later weekday bedtime, and later circadian timing of sleep were associated with IR in a cohort of adolescents with overweight/obesity during the school year. Further research is needed to better understand the physiology underlying these observations and to evaluate the impact of improved sleep and circadian health on metabolic health in this at-risk population.

A simple method to monitor hepatic gluconeogenesis and triglyceride synthesis following oral sugar tolerance test in obese adolescents.

Hepatic energy metabolism is a key element in many metabolic diseases. Hepatic anaplerosis provides carbons for gluconeogenesis (GNG) and triglyceride (TG) synthesis. We aimed to optimize a protocol that measures hepatic anaplerotic contribution for GNG, TG synthesis, and hepatic pentose phosphate pathway (PPP) activity using a single dose of oral [U-13C3]glycerol paired with an oral sugar tolerance test (OSTT) in a population with significant insulin resistance. The OSTT (75 g glucose + 25 g fructose) was administered to eight obese adolescents with polycystic ovarian syndrome (PCOS) followed by ingestion of [U-13C3]glycerol at t = 180 or t = 210 min. 13C-labeling patterns of serum glucose and TG-glycerol were determined by nuclear magnetic resonance. 13C enrichment in plasma TG-glycerol was detectable and stable from 240 to 390 min with the [U-13C3]glycerol drink at t = 180 min(3.65 ± 2.3 to 4.47 ± 1.4%; P > 0.4), but the enrichment was undetectable at 240 min with the glycerol drink at t = 210 min. The relative contribution from anaplerosis was determined at the end of the OSTT [18.5 ±3.4% (t = 180 min) vs. 16.0 ± 3.5% (t = 210 min); P = 0.27]. [U-13C3]glycerol was incorporated into GNG 390 min after the OSTT with an enrichment of 7.5-12.5%. Glucose derived from TCA cycle activity was 0.3-1%, and the PPP activity was 2.8-4.7%. In conclusion, it is possible to obtain relative measurements of hepatic anaplerotic contribution to both GNG and TG esterification following an OSTT in a highly insulin-resistant population using a minimally invasive technique. Tracer administration should be timed to allow enough de novo TG esterification and endogenous glucose release after the sugar drink.

Clinical prediction score of nonalcoholic fatty liver disease in adolescent girls with polycystic ovary syndrome (PCOS-HS index).

OBJECTIVE: Nonalcoholic fatty liver disease (NAFLD) is common in obese adolescents with polycystic ovary syndrome (PCOS), but there are no inexpensive ways to accurately identify NAFLD in PCOS. The objective was to develop a simple clinical score to screen for NAFLD risk in obese adolescents with PCOS. DESIGN: This is a secondary analysis of 3 cross-sectional studies on metabolic characterization of obese adolescents with PCOS. 108 overweight and obese adolescents with PCOS (BMI > 90th percentile, age 12-19 years) were enrolled from 2012 to 2018. METHODS: Magnetic resonance imaging was used to quantify hepatic fat fraction (HFF). A development cohort of 87 girls were divided by presence of NAFLD (HFF > 5.5%). A logistic regression model with the outcome of NAFLD and candidate predictor variables was fit. A simplified model (PCOS-HS index) was created using backwards stepdown elimination. Validation was performed using 200 bootstrapped sample and in a second cohort of 21 PCOS participants. RESULTS: 52% of the development cohort had NAFLD. The PCOS-HS index that included BMI percentile, waist circumference, ALT and SHBG had an AUCROC of 0.81, sensitivity 82%, specificity 69%, negative predictive value (NPV) 78% and positive predictive value 74%, using a threshold of 0.44 to predict HS. A threshold of 0.15 ruled out NAFLD with a NPV 90%. In the validation cohort, the model showed an accuracy of 81%, sensitivity of 91% and specificity of 70%. CONCLUSIONS: We developed a clinical index to identify NAFLD in girls with PCOS who would need further evaluation and treatment.

Skeletal muscle protein accretion rates and hindlimb growth are reduced in late gestation intrauterine growth-restricted fetal sheep.

KEY POINTS: Adults who were affected by intrauterine growth restriction (IUGR) suffer from reductions in muscle mass, which may contribute to insulin resistance and the development of diabetes. We demonstrate slower hindlimb linear growth and muscle protein synthesis rates that match the reduced hindlimb blood flow and oxygen consumption rates in IUGR fetal sheep. These adaptations resulted in hindlimb blood flow rates in IUGR that were similar to control fetuses on a weight-specific basis. Net hindlimb glucose uptake and lactate output rates were similar between groups, whereas amino acid uptake was significantly lower in IUGR fetal sheep. Among all fetuses, blood O2 saturation and plasma glucose, insulin and insulin-like growth factor-1 were positively associated and norepinephrine was negatively associated with hindlimb weight. These results further our understanding of the metabolic and hormonal adaptations to reduced oxygen and nutrient supply with placental insufficiency that develop to slow hindlimb growth and muscle protein accretion. ABSTRACT: Reduced skeletal muscle mass in the fetus with intrauterine growth restriction (IUGR) persists into adulthood and may contribute to increased metabolic disease risk. To determine how placental insufficiency with reduced oxygen and nutrient supply to the fetus affects hindlimb blood flow, substrate uptake and protein accretion rates in skeletal muscle, late gestation control (CON) (n = 8) and IUGR (n = 13) fetal sheep were catheterized with aortic and femoral catheters and a flow transducer around the external iliac artery. Muscle protein kinetic rates were measured using isotopic tracers. Hindlimb weight, linear growth rate, muscle protein accretion rate and fractional synthetic rate were lower in IUGR compared to CON (P < 0.05). Absolute hindlimb blood flow was reduced in IUGR (IUGR: 32.9 ± 5.6 ml min-1 ; CON: 60.9 ± 6.5 ml min-1 ; P < 0.005), although flow normalized to hindlimb weight was similar between groups. Hindlimb oxygen consumption rate was lower in IUGR (IUGR: 10.4 ± 1.4 µmol min-1  100 g-1 ; CON: 14.7 ± 1.3 µmol min-1  100 g-1 ; P < 0.05). Hindlimb glucose uptake and lactate output rates were similar between groups, whereas amino acid uptake was lower in IUGR (IUGR: 1.3 ± 0.5 µmol min-1  100 g-1 ; CON: 2.9 ± 0.2 µmol min-1  100 g-1 ; P < 0.05). Blood O2 saturation (r2  = 0.80, P < 0.0001) and plasma glucose (r2  = 0.68, P < 0.0001), insulin (r2  = 0.40, P < 0.005) and insulin-like growth factor (IGF)-1 (r2  = 0.80, P < 0.0001) were positively associated and norepinephrine (r2  = 0.59, P < 0.0001) was negatively associated with hindlimb weight. Slower hindlimb linear growth and muscle protein synthesis rates match reduced hindlimb blood flow and oxygen consumption rates in the IUGR fetus. Metabolic adaptations to slow hindlimb growth are probably hormonally-mediated by mechanisms that include increased fetal norepinephrine and reduced IGF-1 and insulin.

Using simple clinical measures to predict insulin resistance or hyperglycemia in girls with polycystic ovarian syndrome.

BACKGROUND: Polycystic ovarian syndrome (PCOS) includes insulin resistance (IR) and impaired glucose tolerance (IGT) in youth, and a greatly elevated risk of type 2 diabetes in adulthood. Identifying IR is challenging and documenting IGT requires an oral glucose tolerance test (OGTT). OBJECTIVE: Identify easily applied surrogate measures for IR and IGT in girls with PCOS. METHODS: We studied 28 girls with PCOS (body mass index [BMI] percentile 98 (83.99); 15.5 (14.5,16.6) years of age) and 20 with normal menses [BMI percentile (97 (88.99); 15.5 (13.3,16.1) years]. Hyperinsulinemic-euglycemic clamps (insulin dose of 80 µU/ml/min) to determine glucose infusion rate (GIR) and a 75 g OGTT were performed. Surrogates for IR including fasting insulin, homeostatic model assessment-insulin resistant (HOMA-IR), Matsuda index, and estimate of insulin sensitivity (e-IS) were compared to IGT status and GIR. Spearman correlations were performed between surrogates and GIR or IGT, and receiver operator curve (ROC) analysis to predict GIR below the median or IGT status. RESULTS: GIR was lower in PCOS (12.9 ± 4.6 vs 17.1 ± 5.1 mg/kg fat-free mass·min; P = 0.01). Within PCOS, HOMA-IR (r = -0.78, P < 0.0001), e-IS (r = 0.70, P < 0.001), and Matsuda (r = 0.533, P < 0.001) correlated with GIR. e-IS provided a good sensitivity (100%) and specificity (71%) to identify IR (e-IS cutoff: <6.3, ROC-area under curve = 0.898). Fasting insulin >22 IU/mL had the best sensitivity (88%), specificity (78%), and ROC (0.760) for IGT status. CONCLUSIONS: Girls with PCOS have significant IR, and IGT is common. Both e-IS and fasting insulin are obtainable without an OGTT or clamp and could be used clinically to guide treatment in PCOS.

Achieving ADA/ISPAD clinical guideline goals is associated with higher insulin sensitivity and cardiopulmonary fitness in adolescents with type 1 diabetes: Results from RESistance to InSulin in Type 1 ANd Type 2 diabetes (RESISTANT) and Effects of MEtformin on CardiovasculaR Function in AdoLescents with Type 1 Diabetes (EMERALD) Studies.

OBJECTIVE: Most youth with type 1 diabetes do not meet the American Diabetes Association (ADA) and International Society for Pediatric and Adolescent Diabetes (ISPAD) targets for hemoglobin A1c (HbA1c), blood pressure (BP), lipids, and body mass index (BMI). We hypothesized that ISPAD/ADA goal achievement would be associated with better insulin sensitivity (IS) and cardiopulmonary fitness. METHODS: IS was quantified as glucose infusion rate (GIR) from a hyperinsulinemic-euglycemic clamp in youth with type 1 diabetes from the RESistance to InSulin in Type 1 ANd Type 2 diabetes (RESISTANT) (n = 86) and Effects of MEtformin on CardiovasculaR Function in AdoLescents with Type 1 Diabetes (EMERALD) (n = 41) cohorts (n = 127; age 15.7 ± 2.2 years, 52% girls). Cardiopulmonary fitness was measured as peak oxygen consumption (VO2 peak/kg) during upright (RESISTANT) or supine (EMERALD) cycle ergometry and were stratified by cycle type. Goal achievement was defined as HbA1c < 7.5%, BP < 90th percentile, LDL-cholesterol < 100 mg/dL, HDL-cholesterol > 35 mg/dL, triglycerides < 150 mg/dL and BMI < 85th percentile. Participants were stratified into 3 groups: achieving 0-3 goals (n = 52), 4 goals (n = 48), and 5-6 goals (n = 27). Differences between groups were examined with generalized linear models. RESULTS: IS was lower in youth who met 0-3 goals (5.2 ± 3.4 mg/kg/min) vs those who met 4 goals (7.4 ± 4.1 mg/kg/min, P = .04) and those who met 5-6 goals (8.5 ± 4.3 mg/kg/min, P = .003), and remained significant after adjustments for sex and diabetes duration. Upright VO2 peak was lower in youth who met 0-3 goals (25.8 ± 4.6 mL/kg/min) vs those who met 4 goals (33.0 ± 7.8 mL/kg/min, P = .01) and those who met 5-6 goals (33.2 ± 4.4 mL/kg/min, P = .004). Similar and significant relationships were observed in EMERALD participants for supine VO2 peak. CONCLUSIONS: ADA/ISPAD goal achievement was associated with greater IS and cardiopulmonary fitness.

The role of glycemia in insulin resistance in youth with type 1 and type 2 diabetes.

BACKGROUND: Hyperglycemia has traditionally been considered a major contributor to insulin resistance (IR) in type 1 diabetes (T1D), yet studies examining the relationship between HbA1c and IR are conflicting. Glucose measures captured by continuous glucose monitoring (CGM) (eg, peak glucose, standard deviation, hypoglycemia) in youth have not been explored as predictors of insulin sensitivity (IS). OBJECTIVE: Assess the relationship between IS and glycemia in youth with T1D and type 2 diabetes (T2D). METHODS: Sedentary 12-19 year olds with diabetes had peripheral IS measured by hyperinsulinemic-euglycemic clamp. HbA1c and 3 days of CGM data were also collected. Spearman correlation coefficients were calculated to examine the association between variables. RESULTS: Participants included 100 youth with T1D [46% male, median body mass index (BMI) 74 percentile, HbA1c 8.5%] and 42 with T2D (26% male, BMI 99 percentile, HbA1c 6.9%). Nineteen with T1D and 13 with T2D also wore CGM. In T2D youth, higher HbA1c, average sensor glucose, area under the CGM curve, and metabolic syndrome characteristics correlated with lower IS. In T1D youth, higher BMI percentile, waist circumference, triglycerides, and LDL cholesterol, but not HbA1c, correlated with lower IS. Moreover, higher CGM overnight means glucose correlated with greater IS, and CGM hypoglycemia correlated with lower IS. CONCLUSIONS: Markers of metabolic syndrome and hyperglycemia predicted decreased IS in T2D youth. Paradoxically, hypoglycemia predicted decreased IS in T1D youth and hyperglycemia, particularly overnight, predicted improved IS. These preliminary results imply different mechanisms underlying IR in T1D vs T2D and suggest a role for non-insulin therapies in T1D to improve IR.

Obese adolescents with polycystic ovarian syndrome have elevated cardiovascular disease risk markers.

Women with polycystic ovarian syndrome (PCOS) have evidence of subclinical cardiovascular disease (CVD). However, insulin resistance, an important factor in the development of CVD in adults, is common in adolescents with PCOS, yet data in adolescents are limited. Therefore, we sought to measure insulin resistance and CVD markers in obese youth with and without PCOS. Thirty-six PCOS and 17 non-PCOS adolescent girls who were obese, sedentary, and non-hypertensive were recruited from clinics located within the Children's Hospital Colorado. Following 3 days of controlled diet and restricted exercise, fasting plasma samples were obtained prior to a hyperinsulinemic euglycemic clamp. PCOS girls were more insulin resistant than controls (glucose infusion rate 5.24±1.86 mg/kg/min vs 9.10±2.69; p<0.001). Girls with PCOS had blood pressure in the normal range, but had greater carotid intima-media thickness (cIMT) (0.49±0.07 mm vs 0.44±0.06; p=0.038), beta stiffness index (5.1±1.3 U vs 4.4±0.9; p=0.037), and reduced arterial compliance (1.95±0.47 mm2/mmHg × 10-1 vs 2.13±0.43; p=0.047). PCOS girls had a normal mean lipid profile, yet had a more atherogenic lipoprotein cholesterol distribution and had persistent elevations of free fatty acids despite hyperinsulinemia (68±28 µmol/mL vs 41±10; p=0.001), both potential contributors to CVD. Free fatty acid concentrations correlated best with all CVD markers. In summary, adolescent girls with PCOS have greater cIMT and stiffer arteries than girls without PCOS, perhaps related to altered lipid metabolism, even when clinical measures of blood pressure and cholesterol profiles are 'normal'. Therefore, management of adolescent PCOS should include assessment of CVD risk factor development.

Modeling changes in glucose and glycerol rates of appearance when true basal rates of appearance cannot be readily determined.

Advancing diabetes care requires accurate physiological assessments. Hyperinsulinemic clamps with stable isotope tracers can simultaneously measure insulin's ability to suppress lipolysis and hepatic glucose release. Traditionally, these methods require an assessment of basal glucose and glycerol rate of appearance (Ra). Basal Ra is challenging to measure in insulin-dependent diabetes, where exogenous insulin required to maintain normoglycemia can raise peripheral insulin concentrations sufficiently to suppress basal Ra. Thus we identified two alternative statistical approaches to describe changes in glucose and glycerol Ra that are less reliant on basal assessments. Sixteen youths (4 type 1 diabetic, 4 type 2 diabetic, 4 lean controls, and 4 obese nondiabetic) underwent a four-phase ("basal" and 10, 16, and 80 mU·m(2)·min(-1)) hyperinsulinemic euglycemic clamp with glucose and glycerol tracers. Glucose and glycerol Ra were calculated per phase. A statistical method, the standard two-stage (STS) algorithm, was applied to the individual log insulin vs. Ra curves to calculate a single predicted Ra value. A population-based mixed-effects model (MEM) compared the group average Ra with log insulin curves and described individual deviations from group means and was used to calculate individual predicted Ra. Both models were applied to the participant data, and predicted Ras at the mean insulin concentration per phase (10 for glycerol, 16 for glucose) were calculated, with good agreement between observed and predicted values. In our data set, the MEM was better able to detect group differences. Both STS and MEM can model lipolysis and endogenous glucose release in insulin-dependent states when basal Ra cannot be accurately measured.