Leptin concentrations in type 2 diabetes and non-diabetes Nigerian-Africans

Most studies on leptin in diabetes mellitus (DM) compared to healthy controls were done in Caucasians, with conflicting findings. Paucity of data on this exists in Nigerian-Africans. Therefore, the study determined plasma leptin concentrations in newly diagnosed type-2 diabetes versus controls and its relation to obesity/demographic-metabolic indices. A cross-sectional comparative study on 154 subjects: 67 diabetes and 87 healthy controls at the Ahmadu Bello University Teaching Hospital, Nigeria. Leptin was determined by the sandwich enzyme-linked immunosorbent assay. Mann-Whitney U test, Spearman's Correlation and Step-wise Multiple Logistic Regression analysis of Log-transformed variables determined outcomes. Leptin trended towards lower levels in DM subjects than controls when both sexes were combined, though insignificant (P=0.12). Leptin was significantly (P<0.001) positively correlated with waist circumference (WC) and body mass index (BMI) in DM (WC, r=0.71; BMI, r=0.84) as well as controls (WC, r=0.46, BMI, r=0.51), respectively. Leptin was significantly (P<0.001) higher in females than males, with approximately 2 times Odds of female sex association with log-transformed (Ln₁₀) hyperleptinaemia {Odds Ratio (OR): 1.9, 95% CI, 0.97-3.92, P<0.001}. Age was positively (r=0.21, P=0.05) correlated to leptin in controls, while fasting blood glucose (FBG) negatively correlated to uncontrolled DM (r=-0.26). Leptin showed no significant (P>0.05) correlation to fasting insulin (FI) and HOMA-IR. WC was an independent predictor of Ln₁₀hyperleptinaemia in DM subjects (OR: 1.12, 95% CI, 1.03-1.23, P=0.01). BMI showed significant (P<0.001) association with Ln₁₀hyperleptinaemia in both subjects. Conclusively, leptin trends towards lower levels but are not different in newly diagnosed DM than controls. The association of leptin with obesity is similar but stronger in diabetes than controls, with no relations to FI and HOMA-IR. WC and BMI are independent predictors of hyperleptinaemia.