Objective Obesity and insulin resistance (IR) predispose to type 2 diabetes mellitus. Yet only half of obese adolescents have IR and far fewer progress to type 2 diabetes mellitus. We hypothesized that amino acid and fatty acid metabolites may serve as biomarkers or determinants of IR in obese teens. Research Design and Methods Fasting blood samples were analyzed by tandem mass spectrometry in 82 obese adolescents. A principal components analysis and multiple linear regression models were used to correlate metabolic components with surrogate measures of IR: homeostasis model assessment index of insulin resistance (HOMA-IR), adiponectin, and triglyceride (TG) to high-density lipoprotein (HDL) ratio. Results Branched-chain amino acid (BCAA) levels and products of BCAA catabolism were higher (P < .01) in males than females with comparable body mass index (BMI) z-score. In multivariate analyses, HOMA-IR in males correlated positively with BMI z-score and a metabolic signature containing BCAA, uric acid, and long-chain acylcarnitines and negatively with byproducts of complete fatty acid oxidation (R2 = 0.659, P < .0001). In contrast, only BMI z-score correlated with HOMA-IR in females. Adiponectin correlated inversely with BCAA and uric acid (R2 = 0.268, P = .0212) in males but not females. TG to HDL ratio correlated with BMI z-score and the BCAA signature in females but not males. Conclusions BCAA levels and byproducts of BCAA catabolism are higher in obese teenage boys than girls of comparable BMI z-score. A metabolic signature comprising BCAA and uric acid correlates positively with HOMA-IR in males and TG to HDL ratio in females and inversely with adiponectin in males but not females. Likewise, byproducts of fatty acid oxidation associate inversely with HOMA-IR in males but not females. Our findings underscore the roles of sex differences in metabolic function and outcomes in pediatric obesity.

The objective of this systematic review was to evaluate the association between serum 25-hydroxyvitamin D (25OHD) and cardiometabolic risk in children and the effect of vitamin D supplementation on risk. We included 35 clinical trials, cross-sectional studies, case-control studies, and cohort studies that evaluated the relationship between 25OHD and blood pressure, lipid levels, insulin/glucose metabolism, endothelial dysfunction, and arterial stiffness. One randomized clinical trial that randomized adolescents to 2000 or 400 IU/d of vitamin D and found improvement in arterial stiffness in the high-dose group and worsening in the low-dose group. One cross-sectional study found no relationship between 25OHD and endothelial dysfunction. Of 12 cross-sectional studies, 10 found an inverse association between 25OHD and systolic blood pressure, although 2 trials found no relationship. There was no consistent association between 25OHD and lipid levels or insulin/glucose metabolism. Insufficient evidence was available to conclude that vitamin D supplementation yields cardiometabolic benefit.

The objective of this retrospective cohort study was to evaluate the effectiveness of the Duke University Healthy Lifestyles Program (HLP), a primary care-based childhood obesity treatment program. The study population included obese 2- through 19-year-old patients who entered the HLP between October 2006 through December 2008 and who had a visit to the HLP between the sixth and eighth month after entry. Most of the 282 patients were female (57%) and non-Hispanic/non-White (61%). The median age was 11 years. At baseline, the mean body mass index standard deviation score (BMI SDS) was 2.51, and patients achieved a mean reduction in BMI SDS of 0.10 (standard deviation = 0.20). For patients with baseline and follow-up measures of comorbidities, there were improvements in blood pressure, triglycerides, total cholesterol, and insulin resistance (P < .05). The patients in our obesity program demonstrated a small reduction in the severity of obesity. Improvements occurred in some obesity-associated comorbidities.