Effects of testosterone supplementation therapy on lipid metabolism in hypogonadal men with T2DM: a meta-analysis of randomized controlled trials

Testosterone supplementation may be effective for the treatment of hypogonadism in men with type 2 diabetes mellitus (T2DM), but the evidence from randomized controlled trials (RCTs) is inconclusive. We aimed to systematically summarize results from intervention studies and assess the effects of testosterone supplementation therapy (TST) on lipid metabolism in RCTs of hypogonadal men with T2DM by meta-analysis. PubMed, Embase, and Cochrane Library databases were searched for studies reporting the effect of TST on lipid metabolism in hypogonadal men with T2DM until December 31, 2016. Seven RCTs from 252 trials, enrolling a total of 612 patients in the experimental and control groups with a mean age of 58.5years, were included in this study. The pooled results of the meta-analysis demonstrated that TST significantly decreased TC and TG levels in hypogonadal men with T2DM compared with the control group, with mean differences (MDs) of -6.44 (95% CI: -11.82 to -1.06; I-2=28%; p=0.02) and -27.94 (95% CI: -52.33 to -3.54; I-2=76%; p=0.02).Subgroup analyses revealed that the heterogeneity (I-2=76%) of TG originated from different economic regions, in which economic development, genetic and environmental factors, and dietary habits affect lipid metabolism of human, with a decrease (I-2=45%) in developed countries. Additionally, subgroup analyses showed that TST increased HDL-C level in developing countries compared with the control group (MD=2.79; 95% CI: 0.73 to 4.86; I-2=0%; p=0.008), but there was no improvement in developed countries (MD=1.02; 95% CI: -4.55 to 6.60; I-2=91%; p=0.72). However, LDL-C levels were not improved consistently.Because the relationship between lipid metabolism and atherosclerosis is unequivocal, TST, which ameliorates lipid metabolism, may decrease the morbidity and mortality of cardiovascular disease in hypogonadal men with T2DM by preventing atherogenesis.