Relation between acanthosis Nigricans and insulin sensitivity in overweight hispanic children at risk for type 2 diabetes

OBJECTIVE - To investigate in a population of Hispanic children if 1) the presence of acanthosis nigricans (AN) is related to insulin sensitivity (S-i) independent of adiposity and 2) scale scoring AN severity adds to the clinical estimation of insulin sensitivity, above and beyond the presence or absence AN alone. RESEARCH DESIGN AND METHODS - The study population, 131 Hispanic overweight children (mean BMI percentile 97.0 +/- 3.1, 72 boys, 59 girls, ages 8-13 years, mean Tanner stage 2.4 +/- 1.5) with a family history of type 2 diabetes, underwent a physical examination of the neck to determine AN absence or presence (0-1), AN extent score (0-4 scale), AN texture score (0-3 scale), and an AN combined score (extent + texture; 0-7 scale). S-i was measured by the frequently sampled intravenous glucose tolerance test and minimal modeling. Multivariate linear regression analysis was used to determine the role of BMI and AN in predicting S-i. RESULTS - BMI was the main predictor of S-i, explaining -41% of the variance. The presence of AN explained an additional 4% of the variability in S-i; scale scoring of AN extent or texture did not significantly improve the prediction. CONCLUSIONS - Although AN is an independent risk factor for insulin resistance in overweight Hispanic children at risk for type 2 diabetes, body adiposity is the primary determinant of insulin sensitivity. In addition, scale scoring AN seems of minimal usefulness in clinically estimating the severity of insulin resistance over and above assessing the presence or absence of AN and calculating BMI.