Increased Risk for Type 2 Diabetes in Relation to Adiposity in Middle-Aged Black South African Men compared to Women

Abstract

Aims: Despite a higher prevalence of overweight and obesity in black South African women compared to men, the prevalence of type 2 diabetes does not differ. We explored if this could be due to sex differences in insulin sensitivity, clearance and or beta cell function, and also sex-specific associations with total and regional adiposity. Methods: This cross-sectional study included 804 black South African men (n=388) and women (n=416). Dual-energy x ray absorptiometry was used to measure total and regional adiposity. Insulin sensitivity (Matsuda index), secretion (C peptide index) and clearance (C peptide/insulin ratio) were estimated from an oral glucose tolerance test. Results: After adjusting for sex differences in fat mass index, men were less insulin sensitive and had lower beta cell function than women (p<0.001), with the strength of the associations with measures of total and central adiposity being greater in men than women (p<0.001 for interactions). Further, the association between total adiposity and type 2 diabetes risk was also greater in men than women (relative risk ratio (95% confidence interval): 2.05 (1.42 to 2.96), p<0.001 vs. 1.38 (1.03 to 1.85), p=0.031). Conclusion: With increasing adiposity, particularly increased centralisation of body fat linked to decreased insulin sensitivity and beta cell function, Black African men are at greater risk for type 2 diabetes than their female counterparts.