Objective: To investigate the relationship between fasting plasma leptin concentrations and insulin resistance in Chinese men and women.
Design: Cross-sectional study design.
Subjects: Ninety-six nondiabetic Chinese (51 men and 45 women) with body mass index (BMI) between 18.4-35.8 kg/m2 were studied.
Measurements: Plasma glucose and insulin concentrations were measured every 30 min for 2 h after a 75 g oral glucose load. The degree of insulin resistance was assessed using a modified insulin suppression test. Plasma leptin values were determined by radioimmunoassay.
Results: Fasting plasma glucose, glucose areas, fasting insulin, insulin areas, most of the lipoprotein concentrations and steady state plasma glucose (SSPG) concentrations were relatively similar between men and women. Despite the fact that men had higher BMI values (26.1 +/- 0.5 vs 24.7 +/- 0.5 kg/m2, P < 0.05), fasting plasma leptin concentrations were significantly lower in men than in women (4.9 +/- 0.5 vs 9.0 +/- 0.8 ng/ml, P < 0.001). Fasting leptin values were positively related to SSPG concentrations by simple correlation analysis in both sexes. However, this relationship persisted in men (r = 0.513, P < 0.01) but not in women (r = 0.119, P = NS) after adjustment for BMI. Multiple regression analysis showed that SSPG concentrations, BMI, glucose and insulin responses together accounted for 62.5% and 52.2% of the variation in plasma leptin concentrations in Chinese men and women respectively.
Conclusion: Fasting plasma leptin concentrations were lower in Chinese men than in Chinese women despite the higher BMI observed in men. After adjustment for BMI, plasma leptin values correlated with the degree of insulin resistance in men but not in women.