The 24-hour average concentration of cortisol is elevated in obese African-American youth with type 2 diabetes.

Abstract

24-h average (IC) plasma concentrations of cortisol and growth hormone are lower in obese youth and adults without Type 2 diabetes (T2D) compared to lean subjects. Here we examined IC-cortisol and IC-growth hormone levels in obese youth with and without T2D. We pooled ½-hourly samples from 20 to 24-hour sampling to create an IC for cortisol, cortisone, C-peptide, insulin, growth hormone and cortisol-binding-globulin in obese African-American youth with (n = 8) and without T2D (N = 9). Analytes were assayed by standard methods. The groups were similar in age and sex, all participants had BMI% ≥94. T2D patients had slightly lower BMI z-score (2.25 ± 0.36 versus 2.58 ± 0.16, p = 0.0429). IC-cortisol (5.70 ± 1.8 μg/dl vs 4.18 ± 1.07 μg/dl, p = 0.0481) was higher and IC-C-peptide (2.33 ± 0.89 ng/ml vs 4.36 ± 1.12 ng/ml, p = 0.001) lower in T2D. There were no differences in cortisone/cortisol or for other analytes between groups. IC-cortisol was correlated with IC-cortisone (r = 0.46, p = 0.0471) but not with ICs of insulin, C-peptide, cortisol-binding-globulin, or growth hormone. IC-cortisol levels are higher and IC-C-peptide lower in obese African-American youth with T2D. Higher levels of IC-cortisol in obese youth with T2D may indicate a change in hypothalamic-pituitary-adrenal regulation which may exacerbate hyperglycemia and other metabolic complications of obesity.