Effect of metformin on clinical, metabolic and endocrine outcomes in women with polycystic ovary syndrome: a meta-analysis of randomized controlled trials.

OBJECTIVE: Metformin has been used as a treatment option for polycystic ovary syndrome (PCOS) since 1994; however, more than a hundred randomized clinical trials have reported controversial results regarding the efficacy of metformin in PCOS. This could be due to the small sample size and high variability in methodology between studies. The objective of the present meta-analysis was to determine the effect of metformin on clinical, metabolic, and endocrine outcomes compared to placebo in PCOS women.

METHODS: Randomized controlled trials evaluating the efficacy of metformin were identified using a literature search in PubMed. Bibliographies of relevant studies were also screened to identify additional studies. Data was extracted from included studies and analyzed using RevMan software 5.3 from the Cochrane Collaboration.

MAIN OUTCOME MEASURES: Clinical outcomes included body mass index, waist to hip ratio, systolic and diastolic blood pressure and Ferriman-Gallway score. Metabolic outcomes included total cholesterol, triglycerides, low-density lipoprotein, high-density lipoprotein, very low-density lipoprotein, fasting blood glucose, fasting insulin levels, glucose insulin ratio, HOMA-IR and QUICKI. Endocrine outcomes such as serum testosterone, free testosterone, free androgen index, serum sex hormone binding globulin, dehydroepiandrosterone sulfate, luteinizing hormone, follicle stimulating hormone, LH/FSH ratio, estradiol, and progesterone levels.

CONCLUSION: Metformin showed significant improvement in clinical outcomes but not in metabolic and endocrine outcomes in PCOS women; however, heterogeneity between studies was found to be moderate to high.