Relationship between BMI, total testosterone, sex hormone-binding-globulin, leptin, insulin and insulin resistance in obese men

Abstract

The objective of this work was to evaluate the relationship between sex steroid hormones, sex hormone-binding-globulin, leptin, insulin and insulin resistance in obese men. Anthropometrical indexes, total testosterone (Tt), free testosterone (fT), estradiol (E), sex hormone-binding-globulin (SHBG), glucemia, insulin and leptin were measured in 77 men, with ages between 20 and 60 years. According to their body mass index (BMI), subjects were grouped into three categories: normal body weight (< 24.9 kg/m2), overweight (25-29.9 kg/m2) and obese group (> 30 kg/m2). Insulin resistance index was obtained by the homeostasis assessment model for insulin resistance (HOMA-IR). Total testosterone and SHBG concentrations were lower in the obese group compared with normal and overweight subjects (p < 0.05). The mean insulin concentration was significantly higher in the obese group compared with the other groups (p < 0.05). T was negatively correlated with the BMI (r = -0.447; p < .01), WC (r = -0.464); p < .01, leptin (r = -0.382; p < .01), insulin (r = -0.391; p < 0.01) and also with the HOMA-IR (r = -0.416; p < 0.01). The SHBG negatively and significantly correlated with BMI (r = -0.334; p < 0.01) and WC index (= -0.322; p < 0.01), as well with insulin levels (r = -0.313; p < 0.01) and insulin resistance (= -0.266; p < 0.05). Our results shows that in a sample of men, Tt and SHBG concentrations proportionally diminished with both the increase of BMI and insulin resistance index.