Increased Visceral Adiposity in Obese Adolescents with Hyperglycemia Compared to Normoglycemic Obese Peers

Background: The increase in pediatric obesity in recent decades has led to an increase in the prevalence of type 2 diabetes (T2DM) in children and adolescents. Obesity increases insulin resistance, a known risk factor for T2DM. However, not all adolescents with insulin resistance go on to develop T2DM. Other risk factors, such as family history, also play a role. Excess visceral fat as opposed to subcutaneous fat has been associated with increased metabolic abnormalities. Objective: To investigate the relationship between visceral adiposity and abnormal glucose tolerance in obese adolescents. Methods: This observational cohort study enrolled pubertal children (Tanner stage \u3e1), ages 12 -19 years, BMI 95%ile, and compared those with abnormal glucose tolerance by oral glucose tolerance test (OGTT) or previous diagnosis of T2DM (n=34) (Abnl Gluc Tol), to those with normal glucose tolerance by OGTT (n=80) (Nl Gluc Tol). Visceral fat area (VFAT) was measured by dual x-ray absorptiometry (DXA). VFAT was square root transformed to achieve a normal distribution. Results: Groups were similar in age (14.51 years ± 1.41 (Abnl Gluc Tol) vs 14.49 years ± 1.41 (Nl Gluc Tol), p= 0.94), sex (50% male vs 39% male, p = 0.27), and race (79% African American vs 80% African American, p = 0.77). VFAT was significantly higher in the Abnl Gluc Tol group compared to the Nl Gluc Tol group (90.68 ± 25.22 vs 76.54 ± 25.41, respectively, p = 0.009) by t-test. Linear regression analysis demonstrated that this difference persisted after adjusting for BMI Z-score, age, sex, and race (β =0.892 =p=0.000). Greater BMI z-score, age and male sex were also associated with increased visceral adiposity. Conclusions: Obese adolescents with abnormal glucose tolerance have significantly greater visceral adiposity compared to normoglycemic obese peers, even after adjustment for BMIz-score, sex and age. Future longitudinal studies are needed to determine whether increased visceral adiposity predicts conversion to abnormal glucose tolerance among obese adolescents

Vitamin D3 supplementation in obese, African-American, vitamin D deficient adolescents

Objectives: Obese, African-American (AA) adolescents are at increased risk for vitamin D deficiency. The primary objective of this pilot study was to examine the effect of vitamin D supplementation upon 25-hydroxy vitamin D (25OHD) levels in obese, AA adolescents. Methods: A randomized, double-blinded, controlled pilot study included 26 obese (BMI ≥ 95%ile), vitamin D deficient (25OHD < 20 ng/mL), pubertal AA adolescents (ages 12–17). Subjects received cholecalciferol 1000 IU or 5000 IU daily for 3 months. Serum 25OHD, vitamin D binding protein, parathyroid hormone, and cardiometabolic risk markers were obtained at baseline and post-treatment. Results: Of 39 subjects enrolled, 26 (67%) were vitamin D deficient (mean 25OHD 12.0 ± 3.8 ng/mL) at baseline and were randomized, with 22 completing the study. Sex, age, season, pubertal stage, BMI, insulin resistance (HOMA-IR) and 25OHD were similar at baseline between the 1000 IU and 5000 IU groups. Post-treatment, 25OHD increased less in the 1000 IU group (5.6 ng/mL, p = 0.03) vs. the 5000 IU group (15.6 ng/mL, p = 0.002). 83% of the 5000 IU group and 30% of the 1000 IU group reached post-treatment 25OHD ≥ 20 ng/mL (p = 0.01); 50% of the 5000 IU group, but no subject from the 1000 IU group, achieved 25OHD ≥ 30 ng/mL (p = 0.009). We detected no group differences in mineral metabolites or cardiometabolic risk markers following supplementation. Conclusions: Cholecalciferol dosing in excess of the current Institute of Medicine dietary reference intakes was required to achieve 25OHD levels ≥20 ng/mL in obese, AA adolescents. Supplementation of 5000 IU may be required to achieve the desired goal

Sex differences in the associations of visceral adiposity, homeostatic model assessment of insulin resistance, and body mass index with lipoprotein subclass analysis in obese adolescents.

BACKGROUND: The relationship of lipoprotein particle subclasses to visceral adipose tissue area (VAT-area) in obese children has not been examined previously. OBJECTIVES: The study aims were to compare the relationships of VAT-area, homeostatic model assessment of insulin resistance (HOMA-IR), and body mass index (BMI) with lipids and lipoprotein subclasses in obese adolescents, and to determine if these relationships vary by sex. METHODS: This cross-sectional study of obese adolescents (BMI≥95(th) percentile), ages 12-18y, measured VAT-area by dual energy x-ray absorptiometry (DXA), BMI, fasting lipids, lipoprotein subclasses, and HOMA-IR. Linear regression models evaluated the associations of VAT-area, HOMA-IR, and BMI with lipid cardiometabolic risk factors. Sex-stratified analyses further explored these associations. RESULTS: Included were 127 adolescents (age=14.4±1.5 years; 53.5% female; 88.2% African-American), mean BMI=34.0±5.1 kg/m(2). VAT-area was negatively associated with LDL particle (−P) size (β=−0.28, p=0.0001), HDL-P size (β=−0.33, p<0.0001) and large HDL-P concentration (β=−0.29, p<0.0001), and positively associated with small LDL-P concentration (β=0.23, p=0.0005) and small HDL-P concentration (β=0.25, p=0.05). When VAT-area, HOMA-IR, and BMI associations were compared, VAT-area had the strongest associations with most of the lipoprotein subclasses. After sex-stratification, the associations of VAT-area with HDL cholesterol, LDL-P size, and large LDL-P concentration were significant only for females (all p<0.05). CONCLUSIONS: In a cohort of largely African-American obese adolescents, VAT-area was associated with a more atherogenic lipoprotein subclass profile. When compared to HOMA-IR and BMI, VAT-area had the strongest associations with most lipoprotein subclasses. The relationships between VAT-area and certain lipoprotein subclasses are significantly different in males versus females

Adiponectin Is Associated with Favorable Lipoprotein Profile, Independent of BMI and Insulin Resistance, in Adolescents

Adiponectin levels in adolescents are inversely associated with an atherogenic panel of lipoprotein subclass particles, independent of body mass index and insulin resistance

Body composition estimation using skinfolds in children with and without health conditions affecting growth and body composition.

Background: Body composition prediction equations using skinfolds are useful alternatives to advanced techniques, but their utility across diverse paediatric populations is unknown. Aim: To evaluate published and new prediction equations across diverse samples of children with health conditions affecting growth and body composition. Subjects and methods: Anthropometric and dual-energy X-ray absorptiometry (DXA) body composition measures were obtained in children with Down syndrome (n = 59), Crohn disease (n = 128), steroid-sensitive nephrotic syndrome (n = 67) and a healthy reference group (n = 835). Published body composition equations were evaluated. New equations were developed for ages 3–21 years using the healthy reference sample and validated in other groups and national survey data. Results: Fat mass (FM), fat-free mass (FFM) and percentage body fat (%BF) from published equations were highly correlated with DXA-derived measures (r = 0.71–0.98), but with poor agreement (mean difference = 2.4 kg, −1.9 kg and 6.3% for FM, FFM and %BF). New equations produced similar correlations (r = 0.85–1.0) with improved agreement for the reference group (0.2 kg, 0.4 kg and 0.0% for FM, FFM and %BF, respectively) and in sub-groups. Conclusions: New body composition prediction equations show excellent agreement with DXA and improve body composition estimation in healthy children and those with selected conditions affecting growth