Insulin resistance in obese adolescents.

The prevalence of obesity in adolescents is increasing rapidly. Obesity is associated with insulin resistance, which increases the risk for type 2 diabetes. We investigated insulin resistance in obese adolescents and its relationship to acanthosis nigricans. Height, weight and body mass index (BMI) were measured and each was expressed as a standard deviation score (SDS) based on national growth standards. Insulin resistance was estimated by using the homeostasis model assessment (HOMA-IR) score, calculated as fasting insulin (microU/mL) x fasting glucose (mmol/L)/22.5. Obese adolescents had significantly greater weight-SDS, BMI-SDS, fasting insulin levels, and HOMA-IR than did controls with normal weight. Acanthosis nigricans was present in 58.4% of obese adolescents. Fasting insulin levels and BMI-SDS were positively correlated with the degree of acanthosis nigricans (r = 0.383, P<0.0001 and r = 0.164, P < 0.05, respectively). On multiple regression analysis, HOMA-IR and BMI-SDS explained 16.8% of the degree of acanthosis nigricans (P<0.0001). Acanthosis nigricans thus may be a marker of insulin resistance and should be carefully looked for in obese adolescents.