OBJECTIVETo conduct a meta-analysis on the effects of testosterone on the related factors of metabolic syndrome in hypogonadal males.

METHODSBased on the principles and methods of Cochrane systematic reviews, we searched the PubMed (1980 to August 2009), Embase (1980 to August 2009), the Cochrane Central Register of Controlled Trials and CNKI (1995 to August 2009) , and handsearched some relevant journals and conference proceedings as well. We also identified randomized controlled trials addressing the use of testosterone for the treatment of hypogonadism, screened the retrieved studies according to the predefined inclusion and exclusion criteria, evaluated the quality of the included studies, and performed a meta-analysis on the results of homogeneous studies using the Cochrane Collaboration's RevMan 5.0 software.

RESULTSSix randomized controlled trials were included. The results of analysis indicated that testosterone substitution could significantly ameliorate fasting blood glucose, total cholesterol and insulin resistance in hypogonadism patients, and it could also reduce LDL, HDL, triglyceride and systolic blood pressure, though with no significant difference from the controls. However, there was insufficient evidence to show the effects of testosterone on waist circumference, waist-hip ratio and diastolic blood pressure.

CONCLUSIONExisting clinical evidence has demonstrated the positive effects of testosterone substitution on the improvement of insulin resistance, blood glucose and lipids, but due to the heterogeneity and high risk of bias in the included studies, the evidence might be insufficient to give full support to the demonstration. Further large-scale trials are required to define the metabolic effects of testosterone in the treatment of hypogonadism.