The relationship between testosterone levels, the metabolic syndrome (by two criteria), and insulin resistance in a population of men with organic erectile dysfunction.

Introduction: Erectile dysfunction (ED) in men increases with age, as does cardiovascular disease (CVD). Major risk factors of CVD are similar to ED, including insulin resistance (IR) and metabolic syndrome (MS). Hypogonadism has been associated with MS and IR in general populations.

Aim: To determine the association between hypogonadism and MS and/or IR in men with ED, and to determine if hypogonadism is related to these cardiovascular (CV) risks.

Main Outcome Measures: To compare the mean testosterone levels in men with and without IR and MS, and to show the difference in hypogonadism prevalence in mutually exclusive definitions of MS.

Methods: Mean testosterone for the National Cholesterol Education Program (NCEP) and the World Health Organization (WHO) criteria of MS were calculated using independent t-tests. Multiple range t-tests were used to compare and contrast four groups: (i) only NCEP-Third Adult Treatment Panel criteria; (ii) only the WHO criteria; (iii) men with no MS; and (iv) men fulfilling both MS definitions. Chi-squared analysis was employed to determine the association of hypogonadism with IR.

Results: The prevalence of IR was 79% and of MS was 35 % by the WHO but 43% by the NCEP. Differences in point prevalences were negligible when mutually exclusive groups of MS were compared. Mean free testosterone was lower for the WHO MS or the WHO and NCEP MS (P = 0.04) but not for only the NCEP MS criteria. IR was significantly associated with low free testosterone and hypogonadism (P = 0.02 for each). If more than one criteria were present for either the WHO or NCEP MS, free testosterone was lower (P = 0.02).

Conclusion: MS and IR are strongly associated with lower testosterone and hypogonadism. The WHO criteria are a more sensitive indicator of MS and may predict ED better. Men with ED should not only have CV risks evaluated, but should also have testosterone levels drawn.