Metformin administration improves endothelial function in women with polycystic ovary syndrome

Objective: The aim of this study was to investigate the endothelial status in young women with polycystic ovary syndrome (PCOS), using a simple and easily reproducible hemodynamic method combined with a biological marker and to evaluate the effect of metformin treatment on these parameters. Design: Descriptive clinical trial. Methods: Forty young women, 20 with PCOS and 20 normal women of similar age and body mass index were studied. Metformin (1700 mg daily) was administered for 6 months to the PCOS group. The endothelium status and the metabolic and hormonal profile were studied in both groups, as well as after metformin, by flow-mediated dilatation (FMD) on the brachial artery and by measurements of plasma endothelin-1 (ET-1) levels. Results: FMD was impaired in the PCOS group when compared with controls (3.24 +/- 0.71%, vs 8.81 +/- 1.07% respectively, P < 0.0001), but this difference normalized after metformin treatment (PCOSpost-metformin vs controls: 8.17 +/- 1.26 vs 8.81 +/- 1.07%, P = 0.70) since the values significantly improved after metformin treatment (PCOSpre-metformin VS PCOSpost-metformin: 3.24 +/- 0.71 vs 8.17 +/- 1.26%, P = 0.003). ET-1 levels were significantly higher in the PCOS women compared with the control group (7.23 +/- 0.50 vs 4.99 +/- 0.69 fmol/l, P = 0.01), they improved significantly after metformin treatment (PCOSpre-metformin vs PCOSpost-metformin: 7.23 +/- 0.50 vs 3.57 +/- 0.60 fmol/l, P < 0.0001) and their difference compared with the control group was reversed (PCOSpost-metformin vs controls: 3.57 +/- 0.60 vs 4.99 +/- 0.69fmol/l, P = 0.13). Metformin administration improved hyperandrogenemia. However, in this study, mathematical methods used to assess insulin resistance failed to show any detected alteration after treatment with metformin. Conclusions: PCOS women were found to exhibit endothelial dysfunction compared with controls, which was reversed 6 months after metformin administration.