Gender differences in predictors of insulin resistance in children: Results from NHANES

Context: The prevalence of childhood obesity continues to increase and is associated with an increasing risk of diabetes. Insulin resistance in adult females is associated primarily with body composition while in males it is also associated with cardiovascular fitness. The pattern in children is not well defined and has implications for counseling. Objective: To determine the relationship between insulin resistance, waist circumference, and VO2max among children. Design/Setting: cross-sectional national community-based sample from NHANES 1999-2002. Participants: 2,079 children ages 12-18yr, fasting subsample, 50% male/female. Measures: HOMA, an estimate of insulin resistance calculated from fasting glucose and insulin and log transformed, VO2max from a submaximal treadmill exercise test, waist circumference, BMI. Statistics: Pearson correlation coefficients and linear regression analysis, utilizing SUDAAN with NHANES weights for complex sampling design. Results: In both genders, lnHOMA was significantly correlated with waist circumference and BMI. In males, lnHOMA was significantly and inversely correlated with VO2max, but not in females. In regression analyses controlling for age, race, and BMI, both VO2max and waist circumference were independent predictors of lnHOMA in males (r2 = 0.35) while only waist circumference was an independent predictor in females (r2 = 0.43). When examined by BMI categories, the same pattern of importance of VO2max for males and waist circumference for females was evident in overweight/obese children. Conclusion: Gender specific analyses in children suggest that fitness may be a more important determinant of insulin resistance for males while central adiposity as measured by waist circumference may be the stronger determinant in females.