Cortisol and Its Relation to Insulin Resistance before and after Weight Loss in Obese Children

Abstract

Background: Insulin resistance occurs both in obesity and in Cushing’s syndrome suggesting a pathogenetic role of cortisol in insulin-resistant obese subjects. Methods: We examined serum cortisol in 81 insulin-resistant (homeostasis model assessment (HOMA) >4) obese children (age in median 12 years) and 151 obese children without insulin resistance (HOMA ≤4) (age in median 10 years) and compared these to cortisol of 83 healthy children of normal weight (age in median 12 years). Multivariate linear regression analysis was conducted for the dependent variable insulin resistance (HOMA), including weight status (BMI), age, gender, pubertal stage and cortisol concentration as independent variables. Furthermore, we analyzed cortisol and insulin resistance in 45 obese children with significant weight loss (reduction in SDS-BMI ≧0.5) and in 109 obese children without significant weight loss (reduction in SDS-BMI <0.5) over the time period of 1 year. Results: Cortisol was significantly (p = 0.006) higher in obese insulin-resistant children (median 14.6 µg/dl) compared to those of normal weight (median 11.4 µg/dl) or obese without insulin resistance (median 11.7 µg/dl). Insulin resistance was significantly influenced by weight status (BMI), age and cortisol using multivariate linear regression analysis. A reduction in overweight showed a significant decrease in cortisol (p = 0.005) and insulin resistance (p = 0.002) in insulin-resistant children, whilst there were no significant changes in children not reducing their overweight and in non-insulin-resistant children. Conclusions: Cortisol was moderately increased in insulin-resistant, obese children and related to insulin resistance. Weight reduction led to a decrease in cortisol and insulin resistance. These facts point to an association between cortisol and insulin resistance in obesity.