• J M Lord, I H K Flight, and R J Norman.
• Department of Endocrinology and Metabolism, Peninsula Medical School, South West Centre for Reproductive Medicine, Derriford Hospital, Plymouth, Devon, UK, PL6 8DH.
• Cochrane Db Syst Rev. 2003 Jan 1 (3): CD003053.

BackgroundPolycystic ovary syndrome (PCOS) is characterised by anovulation, hyperandrogenaemia and insulin resistance. Hyperinsulinaemia is known to be associated with an increase in cardiovascular risk and the development of diabetes mellitus. If insulin sensitising agents such as metformin are effective in treating features of PCOS, then they could have wider health benefits than just treating the symptoms of the syndrome.ObjectivesTo assess the effectiveness of insulin sensitising drugs in improving clinical and biochemical features of PCOS.Search StrategyWe searched the Cochrane Menstrual Disorders & Subfertility Group trials register (December 2002), the Cochrane Central Register of Controlled Trials (Cochrane Library, Issue 4, 2002), MEDLINE (January 1966 to December 2002), and EMBASE (January 1985 to December 2002).Selection CriteriaRandomised controlled trials which investigated the effect of insulin sensitising drugs compared with either placebo or no treatment, or compared with an ovulation induction agent.Data Collection And AnalysisPerformed by two reviewers, one blinded to information that could have identified the authors, publisher or results of each study. Fifteen trials were included for analysis, 13 of them using metformin and involving 543 participants.Main ResultsMeta-analysis showed that metformin is effective in achieving ovulation in women with PCOS with odds ratios of 3.88 (CI 2.25 to 6.69) for metformin versus placebo and 4.41 (CI 2.37 to 8.22) for metformin and clomifene versus clomifene alone. An analysis of pregnancy rates suggests a significant treatment effect for metformin and clomifene (OR 4.40, CI 1.96 to 9.85). Metformin has a significant effect in reducing fasting insulin levels (WMD -5.37, CI -8.11 to -2.63), blood pressure and low-density lipoprotein cholesterol (LDL). There was no evidence of effect on body mass index or waist:hip ratio. Metformin was associated with a significantly higher incidence of nausea, vomiting and other gastrointestinal disturbance, but no serious adverse effects were reported.Reviewer's ConclusionsMetformin is an effective treatment for anovulation in women with PCOS. Its choice as a first line agent seems justified, and there is some evidence of benefit on parameters of the metabolic syndrome. Ovulation rates are higher when combined with clomifene (76% versus 46% when used alone), but there is no evidence to indicate whether there is an increased multiple pregnancy rate with this combination. There is no data regarding its safety in long-term use in young women. It should be used as an adjuvant to general lifestyle improvements, and not as a replacement for increased exercise and improved diet.

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