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 Cerrahpaşa Medical Faculty at Istanbul University, Istanbul, Turkey.

PATIENTS: Sixteen insulin-resistant women with PCOS.

INTERVENTIONS: Insulin sensitivity (with an IV 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 cellular mechanism of insulin resistance in PCOS is different from other common insulin-resistant states such as non-insulin dependent diabetes mellitus and obesity.