Testosterone, sex hormone-binding globulin, and the development of type 2 diabetes in middle-aged men - Prospective results from the Massachusetts Male Aging Study

OBJECTIVE - The objective was to examine prospectively the association betw een low testosterone and sex hormone-binding globulin (SHBG) levels and the subsequent development of type 2 diabetes in men. RESEARCH DESIGN AND METHODS - Analyses were conducted on the cohort of the Massachusetts Male Aging Study, a population-based random sample of men age d 40-70. Of the 1,709 men enrolled in 1987-1989 (T-1), 1,156 were followed up 7-10 years later (T-2). Testosterone and SHBG levels at T-1 were used to predict new cases of diabetes between T-1 and T-2. RESULTS - After controlling for potential confounders, diabetes at follow-u p was predicted jointly and independently by lower baseline levels of free testosterone and SHBG. The odds ratio for future diabetes was 1.58 for a de crease of ISD in free testosterone (4 ng/dl) and 1.89 for a 1SD decrease in SHBG (16 nmol/l), both significant at P < 0.02. CONCLUSIONS - Our prospective findings are consistent with previous, mainly cross-sectional reports, suggesting that low levels of testosterone and SH BG play some role in the development of insulin resistance and subsequent t ype 2 diabetes.