Testosterone and Metabolic Syndrome: A Meta‐Analysis Study

Metabolic syndrome (MetS) is often associated with male hypogonadism. Despite the well‐known link, the role of testosterone replacement therapy (TRT) in MetS has not been completely clarified. To systematically analyse the relationship between androgen levels and MetS we performed a review and meta‐analyses of available prospective and cross‐sectional studies. In addition, a specific meta‐analysis on the metabolic effects of TRT in available randomized clinical trials (RCTs) was also performed. An extensive Medline search was performed including the following words “testosterone,” “metabolic syndrome,” and “males”. Out of 323 retrieved articles, 302 articles were excluded for different reasons. Among the 20 published studies included, 13, 3, and 4 were cross‐sectional, longitudinal, and RCTs, respectively. Another unpublished RCT was retrieved on http://www.clinicaltrials.gov. MetS patients showed significantly lower T plasma levels, as compared with healthy individuals. Similar results were obtained when MetS subjects with and without erectile dysfunction were analyzed separately or when NCEP‐ATPIII MetS criteria were compared with other definitions. Meta‐regression analysis demonstrated that type 2 diabetes (T2DM) increased the MetS‐associated T fall. In a multiple regression model, after adjusting for age and BMI, both T2DM and MetS independently predicted low testosterone (adj. r = −0.752; P