Effect of the insulin sensitizers metformin and pioglitazone on endothelial function in young women with polycystic ovary syndrome: a prospective randomized study

ObjectiveTo compare the effect of two different insulin sensitizers, metformin and pioglitazone, on endothelial function in women with polycystic ovary syndrome (PCOS).DesignProspective randomized study.SettingUniversity Hospital endocrinology outpatient clinic.Patient(s)Young women with PCOS (aged 23.3 ± 4.9 years).Intervention(s)Patients were assigned randomly to no treatment (n = 14), metformin 850 mg two times per day (n = 15), and pioglitazone 30 mg daily (n = 14) for 6 months. Healthy age- and body mass index–matched women served as controls (n = 14).Main Outcome Measure(s)Brachial artery flow-mediated dilation was studied at baseline and 6 months.Result(s)Women with PCOS had higher insulin resistance and hyperandrogenism indices and lower flow-mediated dilation compared with controls. The three groups of women with PCOS did not differ at baseline. No differences were observed at follow-up in women who received no treatment. Metformin and pioglitazone improved flow-mediated dilation to a similar extent, restoring it to normal values at 6 months. Both insulin sensitizers induced favorable changes in insulin resistance and hyperandrogenism indices in women with PCOS. Independent predictors of flow-mediated dilation improvement at 6 months were treatment with insulin sensitizers and reduction in insulin resistance.Conclusion(s)In young women with PCOS, treatment with metformin or pioglitazone for 6 months induces a similar beneficial effect on endothelial function; this may be partially attributed to an improvement in insulin resistance. Further research is needed to investigate whether treatment with insulin sensitizers in women with PCOS also reduces cardiovascular risk.