Relationship between serum leptin and insulin resistance among obese Nigerian women

BACKGROUND: Leptin is a hormone produced directly from adipocytes and has been associated with type 2 diabetes mellitus (T2DM) which is characterized by insulin resistance (IR). Due to the increasing prevalence of obesity in sub-Saharan Africa, serum leptin can be explored as a predictive risk factor for T2DM. Therefore, the aim of this study was to determine the relationship between serum leptin and IR among obese women. METHODS: This was a cross-sectional study of obese, adult Nigerian females. Participants with body mass index (BMI) ≥30 kg/m(2) and nondiabetic were recruited as subjects. Fasting serum leptin, insulin, and plasma glucose were determined. IR was calculated using the formula: Homeostatic model assessment-IR (HOMA-IR) = (glucose × insulin)/22.5. Statistical analyses were performed using SPSS and P < 0.05 was considered to be significant. RESULTS: Eighty obese females with mean ± standard deviation BMI 39.1 ± 7.2 kg/m(2) and serum leptin level 48.4 ± 24.4 ng/ml participated in study. Prevalence of hyperleptinemia was 92.5% (confidence interval: 87.3–97.7%). The relationship between leptin and HOMA-IR among the subjects was: BMI 30–34.9 kg/m(2): n = 27, r = 0.18, P = 0.42; BMI 35–39.9 kg/m(2): n = 24, r = 0.36, P = 0.11; BMI ≥ 40 kg/m(2): n = 29, r = 0.52, P = 0.004*; and after controlling for BMI (n = 29, r = 0.46, P = 0.014*). Multiple linear regression showed that leptin did not predict for IR (P = 0.837). CONCLUSION: Serum leptin levels were positively correlated with IR, which was significant among the Class III (morbid) obesity class. However, leptin was not a predictive factor for IR in obese Nigerian women.