Influence of metformin on hyperandrogenism in women with polycystic ovary syndrome: a systematic review and meta-analysis of randomized clinical trials

Purpose To summarize the effects of metformin treatment on markers of hyperandrogenism in patients diagnosed with polycystic ovary syndrome (PCOS). Methods A systematic review, with meta-analysis, of randomized placebo-controlled clinical trials that evaluated the effects of metformin treatment in adult patients with PCOS on the levels of hyperandrogenism markers was conducted. The literature search, data extraction, risk of bias, and the assessment of certainty of evidence were performed independently by two reviewers using a structured form. The results were combined by applying the random effect, and the effect measure presented as a standardized mean difference (SMD). Significant values were considered as p < 0.05 with 95% CI. Furthermore, sensitivity analyses were performed in order to explore possible heterogeneity between studies. Results Were included 18 studies in the quantitative evaluation and 17 studies (23 reports) in the quantitative evaluation. A significant reduction in total testosterone levels was seen in the metformin-treated group when compared to the control group after combining the results by the sensitivity analysis [SMD: − 0.46 (95% CI: − 0.89 to − 0.02)]. Therefore, FAI values were also regulated by metformin treatment. Conclusion We showed that metformin proved to be effective in reducing total testosterone levels, and the same was observed for free androgen index (FAI) values–a measure influenced by testosterone levels. The protocol of this study was registered at Prospero (CRD42021235761).