Can metformin reduce insulin resistance in polycystic ovary syndrome?

Objective: To examine whether metformin is able to reduce insulin resistance in polycystic ovary syndrome (PCOS). Design: Single-blind study comprising two successive periods of treatment: 8 weeks of placebo and 10 weeks of metformin (orally, 850 mg twice daily). Setting: clinic of endocrinology and metabolism of Cerrahpasa Medical Faculty at Istanbul University, Istanbul, Turkey. Patients: Sixteen insulin-resistant women with PCOS. Interventions: Insulin sensitivity (with an TV insulin tolerance test), plasma glucose and insulin levels during an oral glucose tolerance test (OGTT), serum androgens, and lipids were measured at baseline and after each treatment period. Results: Insulin sensitivity, the mean fasting serum levels of glucose, insulin, total cholesterol, triglyceride, low-density Lipoprotein cholesterol, high-density lipoprotein cholesterol, total T, free T, androstenedione, DHEAS, and LH:FSH ratio, and the areas under the curve for plasma glucose and insulin during OGTT were not changed by either placebo or metformin treatment. Conclusion: Metformin does not decrease insulin resistance in PCOS. This finding suggests that the cellular mechanism of insulin resistance in PCOS is different from other common insulin-resistant states such as noninsulin-dependent diabetes mellitus and obesity.