Purpose of review: Metformin has become an established treatment for women with polycystic ovary syndrome, although controversy remains as to how effective it is and in which populations it should be used. This review examines the recent literature in order to ascertain the evidence for the benefits and disadvantages of using metformin in women with polycystic ovary syndrome.
Recent findings: A Cochrane systematic review and metaanalysis examined the evidence for metformin in treating polycystic ovary syndrome. Since this was published there have been a number of new trials, some of which have been reasonably large involving participants from many different countries.
Summary: Evidence shows that metformin is effective in inducing ovulation, has some marginal benefit in improving aspects of the metabolic syndrome, improves objective measures of hirsutism, and seems to be effective in both obese and lean individuals. However, it has significant side effects, and the high levels of effectiveness that were reported by some early trials have not been replicated. Metformin should always be used as an adjuvant to general lifestyle improvements, and not as a replacement for increased exercise and improved diet.