Adiponectin levels in women with polycystic ovary syndrome: impact of metformin treatment in a randomized controlled study

Objective To evaluate the effect of metformin in polycystic ovary syndrome (PCOS). As follow-up on a previous paper describing hormonal and metabolic factors, this paper focuses on correlations between adiponectin and anthropometric, hormonal, and metabolic factors in PCOS and the effect of metformin. Design Randomized, double-blind, placebo-controlled crossover study. Setting District and university hospital. Patient(s) Fifty-two women with PCOS. Three groups were defined according to baseline adiponectin. Intervention(s) Metformin or placebo for 6 months, followed by 3 months' washout before switching to opposite treatment. Blood tests and measurements were performed before and after treatment periods. Main Outcome Measure(s) Adiponectin, insulin, homeostasis model assessment (HOMA) index, and testosterone. Result(s) Waist-hip ratio (WHR), insulin, and HOMA index were significantly higher in the lower adiponectin group than in the upper and middle group, and high-density lipoprotein (HDL) cholesterol was higher in the upper than in the lower adiponectin group. Multiple regression analysis with adiponectin as the dependent variable and HOMA index, HDL cholesterol, testosterone, and WHR as independent variables showed an R2 of 0.43 with β-coefficients of −0.12 for the HOMA index, 0.72 for HDL cholesterol, and −1.49 for WHR. Testosterone did not contribute to the prediction of adiponectin levels. Metformin had no effect on adiponectin in spite of significant decreases in weight, fasting glucose, and insulin resistance. Conclusion(s) In PCOS, adiponectin levels are closely linked to insulin resistance, HDL cholesterol, and abdominal adiposity and unaffected by metformin.