[Glucose tolerance and plasma testosterone concentrations in men. Results of the Asturias Study]

Studies in men have demonstrated a correlation between serum concentrations of androgens and sex hormone binding globulin (SHBG) with the presence of impaired glucose tolerance, diabetes and metabolic syndrome. The aim of this study was to evaluate circulating levels of total testosterone, SHBG, and bioavailable testosterone in the cohort of the Asturias Study and their association with the degree of glucose tolerance and metabolic syndrome.

The study population consisted of 282 men aged 36 to 85 years old with normal concentrations of total testosterone. The degree of glucose tolerance and the presence of metabolic syndrome were evaluated.

Serum concentrations of testosterone and bioavailable testosterone were negatively correlated with age, body mass index, waist circumference, blood glucose, glycated hemoglobin levels and insulin. Serum concentrations of total testosterone, bioavailable testosterone and SHBG were lower in men with glucose intolerance or diabetes than in those with normal glucose tolerance. After multivariate analysis, age and total testosterone levels were independent predictors of the presence of diabetes or glucose intolerance. The risk of glucose intolerance or diabetes mellitus was over 2.5 times higher in men with total testosterone levels in the lowest quartile than in those with total testosterone in the top quartile.

In this general population sample from Asturias, men with lower plasma concentrations of total testosterone--even when within the normal range--have an increased risk of glucose intolerance or diabetes, regardless of age and body mass index.