Relationship between insulin resistance, sex hormones and sex hormone-binding globulin in the serum lipid and lipoprotein profiles of Japanese postmenopausal women.

The purpose of the present study was to investigate the relationship between insulin resistance, sex hormones and sex hormone-binding globulin (SHBG) in regard to the serum lipid and lipoprotein profiles of 82 Japanese postmenopausal women. A multiple regression analysis for lipids, lipoproteins, and apoproteins as dependent variables was performed. All regression models included the following variables as potential independent variables; BMI, percentage of body fat, waist-hip ratio, free testosterone (Free T) and SHBG. In addition, model A included insulin resistance evaluated by HOMA-R and model B included fasting insulin (FIRI). In model A, both Free T and HOMA-R were independent predictors of total-C (TC)/high-density lipoprotein-C (HDL-C) and low-density lipoprotein-C (LDL-C)/HDL-C. The BMI was independently associated with HDL-C. The Free T was a single independent predictor of TC and LDL-C. Both BMI and HOMA-R were independent predictors of triglyceride (TG). In addition, SHBG was also independently associated with apoprotein B (Apo B) and Apo B/Apo AI. In model B, FIRI was an independent predictor of lipid metabolism with similar results to those observed in model A. These results suggest that the lipid characteristics in postmenopausal women might be associated with insulin resistance and/or hyperinsulinemia, and relative hyperandrogenicity which thus induces an increase in the amount of Free T and a decrease in the SHBG within physiological ranges.