Associations of abdominal adiposity, fasting insulin, sex hormone binding globulin, and estrone with lipids and lipoproteins in post-menopausal women

Abstract

The associations of abdominal adiposity, fasting serum levels of insulin, and sex hormones with blood lipids, lipoproteins, and apolipoproteins A-I and B were studied cross-sectionally in 75 healthy, postmenopausal white women. In univariate analyses, abdominal adiposity (increased waist-to-hip girth ratio) and fasting insulin concentrations were negatively and significantly associated ( P < 0.05) with plasma high density lipoprotein cholesterol ( r = −0.47 and −0.38, respectively) and apolipoprotein A-I ( r = −0.37 and −0.36), and positively associated with log triglycerides ( r = 0.54 and 0.33) and apolipoprotein B ( r = 0.43 and 0.22). Sex hormone binding globulin was positively and significantly associated with high density lipoprotein cholesterol ( r = 0.32) and negatively associated with log triglyceride ( r = −0.45) and apolipoprotein B ( r = −0.36). Estrone was positively and significantly associated with high density lipoprotein cholesterol ( r = 0.27), apolipoprotein A-I ( r = 0.23) and negatively associated with low density lipoprotein cholesterol ( r= -0.24) and apolipoprotein B ( r= −0.25). Total estradiol, free estradiol, free testosterone, and total testosterone were more weakly associated with the lipid measures. In multivariate analyses, abdominal adiposity remained significantly associated with high density lipoprotein cholesterol, log triglycerides, apolipoproteins A-I and B after adjustment for sex hormone binding globulin, estrone, and insulin concentrations. Insulin remained associated only with apolipoprotein A-I after adjustment for abdominal adiposity, estrone, and sex hormone binding globulin. Sex hormone binding globulin remained marginally associated with log triglyceride ( P = 0.07) after adjustment for the remaining three factors. Estrone remained significantly associated with high density lipoprotein cholesterol. These findings emphasize the potential importance of abdominal adiposity on the relationships of sex hormones and insulin to lipid measures in post-menopausal women. The atherogenic lipid profile of abdominal adiposity appears to be partly mediated through insulin, estrone and sex hormone binding globulin, but it seems likely that other mechanisms also contribute.