Effects of testosterone treatment on glucose metabolism and symptoms in men with type 2 diabetes and the metabolic syndrome: a systematic review and meta‐analysis of randomized controlled clinical trials

Summary Context The effects of testosterone treatment on glucose metabolism and other outcomes in men with type 2 diabetes (T2D) and/or the metabolic syndrome are controversial. Objective To perform a systematic review and meta‐analysis of placebo‐controlled double‐blind randomized controlled clinical trials ( RCT ) of testosterone treatment in men with T2D and/or the metabolic syndrome. Data sources A systematic search of RCT s was conducted using Medline, Embase and the Cochrane Register of controlled trials from inception to July 2014 followed by a manual review of the literature. Study selection Eligible studies were published placebo‐controlled double‐blind RCT s published in English. Data extraction Two reviewers independently selected studies, determined study quality and extracted outcome and descriptive data. Data synthesis Of the 112 identified studies, seven RCT s including 833 men were eligible for the meta‐analysis. In studies using a simple linear equation to calculate the homeostatic model assessment of insulin resistance ( HOMA 1), testosterone treatment modestly improved insulin resistance, compared to placebo, pooled mean difference ( MD ) −1·58 [−2·25, −0·91], P  < 0·001. The treatment effect was nonsignificant for RCT s using a more stringent computer‐based equation ( HOMA 2), MD −0·19 [−0·86, 0·49], P  = 0·58). Testosterone treatment did not improve glycaemic (HbA1c) control, MD −0·15 [−0·39, 0·10], P  = 0·25, or constitutional symptoms, Aging Male Symptom score, MD −2·49 [−5·81, 0·83], P  = 0·14). Conclusions This meta‐analysis does not support the routine use of testosterone treatment in men with T2D and/or the metabolic syndrome without classical hypogonadism. Additional studies are needed to determine whether hormonal interventions are warranted in selected men with T2D and/or the metabolic syndrome.