The age related decrease in testosterone is significantly exacerbated in obese men with the metabolic syndrome. What are the implications for the relatively high incidence of erectile dysfunction observed in these men?

Purpose: We examined pooled baseline data from 2 lipid treatment studies to evaluate the relationship among total serum testosterone levels, obesity and the metabolic syndrome in aging men. Materials and Methods: Baseline total serum testosterone, lipid, glycemic and anthropometric data were obtained from 864 men (mean age 52 years) participating in 2 lipid treatment studies. Inclusion criteria for the 2 studies included low-density lipoprotein cholesterol 130 to 160 mg/dl and triglycerides 350 mg/dl or less. Results: For all patients as well as the nonmetabolic syndrome and the metabolic syndrome cohorts, testosterone decreased with increasing body mass index (p < 0.0001 for Pearson correlation coefficient in all 3 cohorts). Mean baseline total serum testosterone levels in obese and severely obese aging men with the metabolic syndrome were around 150 and 300 ng/dl, respectively, less than that in aging, lean men with no metabolic syndrome. The relative contributions of each of the individual National Cholesterol Education Program Adult Treatment Panel III components of the metabolic syndrome to low serum testosterone in aging men was examined using multiple linear regression modeling. Based on these analyses the presence of diabetes or fasting serum glucose greater than 110 mg/dl, body mass index 30 kg/m(2) or greater, and triglycerides 150 mg/dl or greater each appeared to have a clinically relevant association with low serum testosterone. Conclusions: This study demonstrated that aging men with obesity and the metabolic syndrome have a significant decrease in total serum testosterone levels compared to aging, metabolically healthy men. These data suggest that the well established association between erectile dysfunction and pre-diabetes/diabetes (particularly in obese pre-diabetic/diabetic patients) may involve a hormonal component.