Changes in glucose tolerance with metformin treatment in polycystic ovary syndrome: A retrospective analysis

ObjectiveTo determine whether treatment with metformin would prevent progression to glucose intolerance and type 2 diabetes in women with polycystic ovary syndrome (PCOS).MethodsWe conducted a retrospective review of medical records of women treated for PCOS during a 5-year period. Eligibility criteria included exclusion of diabetes at baseline by an oral glucose tolerance test, treatment with metformin, and a repeated oral glucose tolerance test after at least 1 year of metformin therapy. Fifty women with PCOS fulfilled the eligibility criteria.ResultsAt baseline, 11 women (22%) had impaired glucose tolerance (IGT), and 39 (78%) had normal glucose tolerance (NGT). After treatment with metformin, IGT persisted in 5 (45%) of the 11 women who had IGT at baseline, whereas 6 (55%) had reversion to NGT. During a mean treatment period of 43.3 months, 2 (5%) of the 39 women with baseline NGT had conversion to IGT, resulting in an annual conversion rate from NGT to IGT of 1.4%. In comparison with the 16% to 19% annual conversion rate reported in the literature, metformin treatment in this study resulted in an 11-fold decrease in the annual conversion rate from NGT to IGT (P = 0.01). None of the 50 women developed diabetes.ConclusionThe findings of this retrospective study suggest that long-term treatment with metformin delays or prevents the development of IGT and type 2 diabetes in women with PCOS. (Endocr Pract. 2007;13:373-379)