Association of plasma leptin levels and insulin resistance in diabetic women: a cross-sectional analysis in an Iranian population with different results in men and women

Objectives. The objective of this study was to assess the association of serum leptin levels with insulin resistance (IR), metabolic syndrome (MetS), lipid levels, and glucose control in an Iranian type 2 diabetic population. Findings. In this cross-sectional analysis, 132 type 2 diabetic patients (79 women) and 71 healthy non-diabetic and non-hypertensive individuals (40 women; as control subjects) were included. Homeostasis model assessment (HOMA) of insulin values >= 1.8 for females and 1.7 for males was regarded as the cut-point of IR. MetS was defined according to updated 2005 NCEP ATP III criteria. The leptin correlated with HOMA-IR values without adjustment (r = 0.24; p < 0.005) and with adjustment for sex and diabetes (r = 0.44; p < 0.005). Sex had significant effect on the BMI adjusted association of HOMA-IR (quintiles) and leptin (df = 4 F(12.7) = 3.5; p = 0.011). In diabetic women (but not men), leptin levels were different between those with and without IR (27.3 +/- 1.9 vs. 18.2 +/- 3.3; p < 0.05). BMI adjusted leptin values were different between subjects with and without MetS (22.2 +/- 1.7 vs. 14.8 +/- 1.2; p < 0.001). No association was noticed between BMI-adjusted leptin with glycated hemoglobin or blood lipid levels. Conclusions. In this study, plasma leptin concentration correlated with IR independent of the effect of obesity in female but not male diabetic subjects.