Androgenicity and obesity are independently associated with insulin sensitivity in postmenopausal women

Abstract

An increase in androgenicity may contribute to the development of insulin resistance in postmenopausal women. Increased androgenicity in women has been found to be associated with the development of type 2 diabetes. In addition, obesity and central obesity are associated with greater androgenicity. Insulin sensitivity, androgenicity, and body composition were characterized in 34 nondiabetic postmenopausal women age 72 ± 1 years (mean ± SEM) to test the hypothesis that androgenicity is a predictor of insulin sensitivity independent of measures of obesity. Androgenicity was measured using levels of sex hormone-binding globulin (SHBG), total and free testosterone, dehydroepiandrosterone sulfate (DHEA-S), androstenedione, and free androgen index (FAI). Insulin sensitivity (S I) was determined from a frequently sampled intravenous glucose tolerance test. Body composition measures included body mass index (BMI) and dual energy x-ray absorptiometry measurements of total and central fat mass. S I was found to be associated with total fat mass ( r = −.51, P = .002), central fat mass ( r = −.62, P = .0001), BMI ( r = −.55, P = .0008), SHBG levels ( r = .65, P = .0001), and FAI ( r = −.41, P = .01). SHBG levels were inversely correlated with central fat mass ( r = −.59, P = .0002). Using multiple regression, SHBG and central fat mass were the only significant independent predictors of S I, accounting for 50% of its variance ( r = .71, P = .0001); total fat mass, BMI, total and free testosterone, DHEA-S, androstenedione, and FAI did not enter the model. We conclude that there is a significant association between insulin sensitivity and androgenicity in postmenopausal women that is independent of obesity. Interventions to decrease androgenicity may therefore be useful in improving insulin sensitivity in postmenopausal women.