The prevalence of obesity in children is reaching epidemic proportions. Excess adiposity is more than just a cosmetic problem, having substantial metabolic consequences. Insulin resistance, hyperinsulinemia, impaired glucose tolerance, and frank diabetes are often seen in obese children. In this study the prevalence of impaired glucose (carbohydrate) tolerance in lean children with a family history of diabetes and obese children with acanthosis nigricans with or without a family history of diabetes mellitus will be studied.