Glucocorticoids associate with cardiometabolic risk factors in black South Africans

Circulating glucocorticoids are associated with the metabolic syndrome and related cardiometabolic risk factors in non-Africans. This study investigated these associations in Africans, whose metabolic phenotype reportedly differs from Europeans. Measures of adiposity, blood pressure, glycaemia, insulin resistance, and lipid profile, were measured in 316 African men and 788 African women living in Soweto, Johannesburg. The 2009 harmonized criteria were used to define the metabolic syndrome. Serum glucocorticoids were measured using liquid chromatography-mass spectrometry. Cortisol was associated with greater odds of presenting with the metabolic syndrome (odds ratio (95% confidence interval, 95%CI) =1.50 [1.04, 2.17] and higher systolic (beta coefficient, β (95%CI) =0.04 [0.01, 0.08]) and diastolic (0.05 [0.02, 0.09]) blood pressure, but higher HDL (0.10 [0.02, 0.19]) and lower LDL (-0.14 [-0.24, -0.03]) cholesterol concentrations, in the combined sample of men and women. In contrast, corticosterone was only associated with higher insulin sensitivity (Matsuda index; 0.22 [0.03, 0.41]), but this was not independent of BMI. Sex-specific associations were observed, such that both cortisol and corticosterone were associated with higher fasting glucose (standardized β (95%CI): 0.24 [0.12, 0.36] for cortisol; and 0.12 [0.01, 0.23] for corticosterone) and HbA1c (0.13 [0.01, 0.25] for cortisol; and 0.12 [0.01, 0.24] for corticosterone) in men only, but lower HbA1c (0.10 [ -0.20, -0.01] for cortisol; and -0.09 [-0.18, -0.03] for corticosterone) in women only. Our study reports for the first time that associations between circulating glucocorticoid concentrations and key cardiometabolic risk factors exhibit both glucocorticoid- and sex-specificity in Africans.