Predictors of changes in glucose tolerance status in obese youth.

OBJECTIVE Type 2 diabetes in obese youth is an emerging problem. The metabolic and anthropometric predictors of change in glucose tolerance status in obese youth are unknown. RESEARCH DESIGN AND METHODS A total of 117 obese children and adolescents were studied by performing an oral glucose tolerance test (OGTT) at baseline and after approximately 2 years. Data from both OGTTs and changes in weight were examined to identify youth at highest risk for developing diabetes and the factors that have the strongest impact on glucose tolerance. RESULTS Eighty-four subjects had normal glucose tolerance (NGT) and 33 impaired glucose tolerance (IGT) at baseline. Eight subjects (all of whom had IGT at baseline) developed type 2 diabetes, whereas 15 subjects with IGT reverted to NGT. In this cohort, severe obesity, impaired glucose tolerance, and African-American background emerged as the best predictors of developing type 2 diabetes, whereas fasting glucose, insulin, and C-peptide were nonpredictive. Changes in insulin sensitivity, strongly related to weight change, had a significant impact on the 2-h glucose level on the follow-up study. CONCLUSIONS Severely obese children and adolescents with IGT, particularly of African-American descent, are at very high risk for developing type 2 diabetes over a short period of time. Parameters derived from an OGTT and not fasting samples can serve as predictors of changes in glucose tolerance.