Effects of pioglitazone treatment on blood leptin levels in patients with type 2 diabetes

AIMS/INTRODUCTION: The aim of the present study was to carry out a meta‐analysis of randomized controlled trials (RCTs) that investigated the effects of pioglitazone on blood leptin levels in patients with type 2 diabetes. MATERIALS AND METHODS: Literature searches were carried out using Medline, the Cochrane Controlled Trials Registry and ClinicalTrials.gov, and RCTs that investigated the effects of pioglitazone on blood leptin levels in patients with type 2 diabetes were selected. Standardized mean differences and 95% confidence intervals were calculated. RESULTS: A total of 10 RCTs met the eligibility criteria and were included in the meta‐analysis. Significantly lower blood leptin levels were observed in the pioglitazone group (standardized mean difference −0.58, 95% confidence interval −1.12 to −0.05%, P = 0.03) than in the placebo group. There was no significant difference in blood leptin levels observed between the pioglitazone and oral antidiabetic drug groups (standardized mean difference −0.01, 95% confidence interval −0.20 to 0.19%, P = 0.93). CONCLUSIONS: There was a significant difference in blood leptin levels between the pioglitazone and placebo groups. However, relatively few RCTs were included in the study, and there was a high level of statistical heterogeneity; we believe that this could have affected the results.