Introduction: Type 2 diabetes mellitus (T2DM) is often associated with male hypogonadism. The role of testosterone replacement therapy (TRT) in T2DM has not been completely clarified. To systematically analyse the relationship between androgen levels and T2DM by reviewing and meta-analyzing available prospective and cross-sectional studies. In addition, a specific meta-analysis on the metabolic effects of TRT in available randomised clinical trials (RCTs) was also performed.
Methods: An extensive Medline search was performed including the following words testosterone, type 2 diabetes mellitus and males. Out of 742, 37 articles were included in the study. In particular 28, 5, and 3 were cross-sectional, longitudinal, and interventional studies, respectively. A further unpublished RCT was retrieved on www.clinicaltrials.gov.
Results: T2DM patients showed significantly lower T plasma levels in comparison with non-diabetic individuals. Similar results were obtained when T2DM subjects with and without ED were analyzed separately. Meta-regression analysis demonstrated that aging reduced, while obesity increased, these differences. However, in a multiple regression model, after adjusting for age and BMI, T2DM was still associated with lower total T (TT) levels (adj. r=−0.568, P<0.0001). Analysis of longitudinal studies demonstrated that baseline TT was significantly lower among patients with incident diabetes in comparison to controls (−2.8 (3.57; −0.59), P<0.001). Combining the results of RCTs, TRT was associated with a significant reduction of fasting plasma glucose, HbA1c, fat mass, and triglycerides.
Conclusions: T2DM can be considered independently associated with male hypogonadism. Although only few RCTs have been reported, TRT seems to improve glycometabolic control as well as fat mass in T2DM subjects.
30 Apr - 04 May 2011
European Society of Endocrinology