Sex differences in the association of endogenous sex hormone levels and glucose tolerance status in older men and women.
OBJECTIVE: Some evidence suggests an inverse association between type 2 diabetes and androgens in men and a positive association between type 2 diabetes and androgens in women. The purpose of this community-based study was to evaluate sex differences in the association between endogenous total and bioavailable estrogen and testosterone levels and glucose tolerance status. RESEARCH DESIGN AND METHODS: We included in this study 775 men and 633 postmenopausal non-estrogen-using women, all > or =55 years of age (mean ages 72 and 75 years, respectively). A 75-g oral glucose tolerance test (OGTT) was administered to fasting subjects from 1984 to 1987, when sera were frozen for measurement of total and bioavailable hormone levels. Total testosterone and estradiol levels were measured by radioimmunoassay, and bioavailable hormone levels were determined using a modified ammonium-sulfate precipitation method. The association between steroid hormones and glucose tolerance status was tested. RESULTS: In sex-specific age- and BMI-adjusted analyses, men with impaired glucose tolerance (IGT) had significantly lower total testosterone levels. Women with IGT or type 2 diabetes had significantly higher bioavailable testosterone and total and bioavailable estradiol levels than those with normal glucose tolerance. Total testosterone and fasting plasma glucose were inversely associated in men (P = 0.0001), whereas bioavailable testosterone and estradiol were positively associated with fasting plasma glucose in women (P = 0.0001 and 0.001, respectively). CONCLUSIONS: Additional studies are needed to further develop the hormone-diabetes connection.