Objective 　To evaluate the efficacy and safety of metformin for metabolic syndrome.
Methods 　We searched The Cochrane Library, MEDLINE, EMBASE, China Biological Medicine Database, VIP, and CMAC up to the year of 2007. Handsearches and additional searches were also conducted. Randomized controlled trials of metformin for metabolic syndrome were included. Two reviewers independently extracted data from eligible studies and evaluated the quality of included studies. Meta-analysis was performed for the results of homogeneous studies by The Cochrane Collaboration’s software RevMan 4.2.9.
Results 　Six trials involving a total of 2442 patients with metabolic syndrome were included. Meta-analysis was not performed due to the apparent heterogeneity. Metformin, compared with placebo, exhibited more favorable effects in reducing the proportion of patients with metabolic syndrome (RR 1.27, 95% CI 1.01 to 1.60), the proportion of patients with low HDL-c (RR 1.61, 95%CI 1.16 to 2.23), wide waist circumference (RR 1.64, 95%CI 1.06 to 2.55), and high FPG (RR 1.55, 95%CI 1.17 to 2.05). Metformin was also more effective in improving FPG and insulin sensitivity. The addition of metformin to atenolol plus nitrendipine was superior to atenolol plus nitrendipine alone in reducing the proportion of patients with high TG (RR 5.57, 95%CI 1.56 to 19.84), abdominal obesity (RR 14.47, 95%CI 3.34 to 62.61), and IGT (RR 16.51, 95%CI 6.06 to 45.0). Compared with low-fat diet therapy, metformin was superior in improving FPG, 2-hour postload plasma glucose, and insulin sensitivity. No differences were observed between metformin and acarbose in the reduction of TG and FPG, but metformin was less effective than acarbose in improving 2-hour postload plasma glucose. No adverse drug reactions were reported.
Conclusion 　 Metformin has beneficial effects in reducing the incidence of high FPG, IGT, and abdominal obesity. It also proved beneficial in reducing the prevalence of metabolic syndrome and increasing insulin sensitivity. The therapeutic effects of metformin on blood pressure, obesity, and lipid profile are uncertain. There is insufficient evidence to recommend the use of metformin in the treatment of metabolic syndrome due to low methodological quality, small sample size, and limited number of trials. More high quality, large-scale randomized controlled trials are required.

Citation： GOU Zhongping,LI Xiujun,WU Taixiang. Lipid-modifying Therapy for Metabolic Syndrome: A Systematic Review. Chinese Journal of Evidence-Based Medicine, 2008, 08(11): 980-987. doi: 10.7507/1672-2531.20080217 Copy