Adiponectin is associated with insulin sensitivity in white European men but not black African men

Abstract

Aims: We aimed to assess ethnic differences in inflammatory markers and their relationships with insulin sensitivity and regional adiposity between white European and black African men.

Methods: A total of 53 white European and 53 black African men underwent assessment of inflammatory markers alongside Dixon-magnetic resonance imaging to quantify subcutaneous and visceral adipose tissue and intrahepatic lipid. A hyperinsulinaemic-euglycaemic clamp was used to measure whole-body and adipose tissue insulin sensitivity. To assess ethnic differences in relationships, the statistical significance of an interaction term between adipokines and ethnic group was tested in multivariable regression models.

Results: The black African men exhibited significantly lower adiponectin and tumour necrosis factor-α (TNF-α) and greater interleukin-10 (IL-10) compared to white European men (all p < 0.05). There were no statistically significant ethnic differences in leptin, resistin, IL-6, interferon-γ, IL-13, IL-1β, IL-8 and vascular endothelial growth factor. Several relationships differed significantly by ethnicity such that they were stronger in white European than black African men including IL-6 with visceral adipose tissue; adiponectin with subcutaneous adipose tissue; leptin with intrahepatic lipid; adiponectin, IL-6 and TNF-α with whole-body insulin sensitivity and TNF-α with adipose tissue insulin sensitivity (all pinteraction <0.05). Leptin significantly predicted whole-body insulin sensitivity in white European (R² = 0.51) and black African (R² = 0.29) men; however, adiponectin was a statistically significant predictor in only white European men (R² = 0.22).

Conclusions: While adiponectin is lower in black African men, its insulin sensitising effects may be greater in white men suggesting that the role of adipokines in the development of type 2 diabetes may differ by ethnicity.

Keywords: African; adipokine; ethnicity; inflammation; type 2 diabetes.