Epidemiology: testosterone and the metabolic syndrome.

Low levels of testosterone, hypogonadism, have several common features with the metabolic syndrome. In the Tromsø Study, a population-based health survey, testosterone levels were inversely associated with anthropometrical measurements, and the lowest levels of total and free testosterone were found in men with the most pronounced central obesity. Total testosterone was inversely associated with systolic blood pressure, and men with hypertension had lower levels of both total and free testosterone. Furthermore, men with diabetes had lower testosterone levels compared to men without a history of diabetes, and an inverse association between testosterone levels and glycosylated hemoglobin was found. Thus, there are strong associations between low levels of testosterone and the different components of the metabolic syndrome. In addition, an independent association between low testosterone levels and the metabolic syndrome itself has recently been presented in both cross-sectional and prospective population-based studies. Thus, testosterone may have a protective role in the development of metabolic syndrome and subsequent diabetes mellitus and cardiovascular disease in aging men. However, clinical trials are needed to confirm this assumption.