Predicting Impaired Glucose Tolerance in Overweight African-American Adolescents

Abstract

Childhood obesity is associated with type 2 diabetes (T2DM) and impaired glucose tolerance (IGT). However, not all overweight adolescents exhibit these conditions suggesting that additional factors mediate the consequences of adolescent obesity. Typically screening for IGT/T2DM is limited to symptomatic, older and more severely obese adolescents. PURPOSE: We investigated whether fitness level (VO2peak), self-reported physical activity, family history of T2DM, severity of obesity, age, and gender predicted IGT in overweight African-American adolescents (AAA). METHODS: Overweight AAA (n=110, mean age=14.4 yrs, 61% female) had relative body mass index (RBMI) calculated as a measure of obesity severity, and completed an oral glucose tolerance test (1-gm glucose/kg) and a treadmill cardiopulmonary test with measurement of VO2peak. IGT was defined as fasting blood glucose ≥100 and <126 mg/dl or 2-hr post-load glucose ≥140 and <200 mg/dl). A 7-day physical activity recall interview was conducted and family history of T2DM was obtained via parental report. IGT group differences was examined using t-tests and Chi-square. Multivariate logistic regression was done to predict IGT. RESULTS: IGT was present in 23% (n=25). The IGT group was similar in age (14.3 vs. 14.4 yrs, p= 0.56), family history of T2DM (66% vs. 61%, p=0.62), RBMI (193 vs. 183, p=0.36), VO2peak (21.5 vs. 20.9 ml/kg/min, p=0.64) compared to the non-IGT group. No differences in self-reported physical activity were found with both groups engaging in <3 days per week of at least 30 minutes of moderate activity and sitting >10 hr on weekdays. Boys were more likely than girls to have IGT (33% vs. 15%, p=0.02; OR: 2.75; 95th CI: 1.10-6.87, p=0.03). Neither severity of obesity, age, family history of T2DM, VO2peak, nor physical activity predicted IGT in this group of predominantly sedentary, overweight AAA. CONCLUSIONS: IGT is prevalent in overweight, sedentary AA adolescents. While national statistics indicate female AAA have a higher prevalence of obesity, our group of obese male AAA had a greater likelihood of IGT. Because neither age, severity of obesity, or family history of type 2 diabetes predict IGT in overweight AA adolescent, these demographics should not be used to limit screening for IGT in this population.