Helena J. Teede

Objective Characteristic features of polycystic ovary syndrome (PCOS) include insulin resistance and an increased risk for type 2 diabetes. To promote improved insulin sensitivity, insulin sensitisers have been used in PCOS. However, direct comparisons across these agents are limited. This study compared the effects of metformin, rosiglitazone and pioglitazone in the management of PCOS to inform the 2023 International Evidence‐based PCOS Guideline. Design Systematic review and meta‐analysis of the literature. Patients Women with PCOS and treatment with insulin sensitisers. Measurements Hormonal and clinical outcomes, as well as side effects. Results Of 1660 publications identified, 13 randomised controlled trials were included. Metformin was superior in lowering weight (mean difference [MD]: −4.39, 95% confidence interval [CI]: −7.69 to −1.08 kg), body mass index (MD: −0.95, 95% CI: −1.41 to −0.49 kg/m 2 ) and testosterone (MD: −0.10, 95% CI: −0.18 to −0.03 nmol/L) versus rosiglitazone, whereas there was no difference when comparing metformin to pioglitazone. Adding rosiglitazone or pioglitazone to metformin did not improve metabolic outcomes. However, rosiglitazone seemed superior to metformin in lowering lipid concentrations. Conclusions Metformin should remain the first‐line insulin sensitising treatment in adults with PCOS for the prevention and management of weight and metabolic features. The addition of thiazolidinediones appears to offer little benefit.