Metformin shows limited impact on gonadotropin levels in PCOS women

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Diabetes, obesity & metabolism Published June 1, 2026 Medically reviewed June 1, 2026 Study authors: Krysiak Robert, Simental-Mendía Mario, Simental-Mendía Luis E PubMed ↗ DOI ↗ By Dr. Sofia Müller, MD · Lifespan & Whole-Person Care

Key Takeaway

Metformin does not change FSH or LH but significantly increases the LH/FSH ratio in PCOS women.

A systematic review and meta-analysis of 51 randomized controlled trials evaluated the effects of metformin on gonadotropin levels in women with polycystic ovary syndrome (PCOS). The primary outcomes were follicle-stimulating hormone (FSH), luteinizing hormone (LH), and the LH/FSH ratio. The analysis found that metformin treatment did not significantly affect FSH levels, with a weighted mean difference of -0.22 IU/L (95% CI: -0.54 to 0.11, p=0.19). Similarly, LH levels were unchanged, with a WMD of 0.11 IU/L (95% CI: -0.38 to 0.60, p=0.66).

However, the LH/FSH ratio showed a significant increase with metformin, with a WMD of 0.24% (95% CI: 0.06 to 0.43, p=0.01). This suggests a specific hormonal shift rather than broad gonadotropin suppression. Safety data were not reported in the included studies, limiting conclusions on tolerability.

A key limitation is that the effect size for all outcomes was sensitive to one study in sensitivity analyses, indicating potential fragility in the results. The findings highlight that metformin's primary benefit in PCOS may not be through direct modulation of FSH or LH, but through altering their ratio, which could influence ovulatory function.

Study Details

Study typeMeta analysis

EvidenceLevel 1

PublishedJun 2026

PMID41891336

View Original Abstract ↓

AIMS: This study aimed to explore the impact of metformin on gonadotropin levels in women with polycystic ovary syndrome (PCOS) based on a meta-analysis of randomised controlled trials (RCTs). METHODS: The search process was performed in PubMed, Scopus, Web of Science, ClinicalTrials.gov and Google Scholar. RCTs were eligible for meta-analysis if they had a parallel or crossover design and reported gonadotropin levels before and after metformin treatment. A random-effects model and the generic inverse variance method were used for meta-analysis. RESULTS: The meta-analysis of 51 RCTs, 48 of which included only and 2 included predominantly women with PCOS, showed that metformin treatment did not affect FSH (WMD: -0.22 IU/L, 95% CI: -0.54, 0.11, p = 0.19, I = 84%) or LH (WMD: 0.11 IU/L, 95% CI: -0.38, 0.60, p = 0.66, I = 75%), but it significantly increased the LH/FSH ratio (WMD: 0.24%, 95% CI: 0.06, 0.43, p = 0.01, I = 93%). Additionally, the effect size was sensitive to one study for FSH, LH and LH/FSH ratio following the sensitivity analysis. CONCLUSION: Our meta-analysis, the largest one conducted to date, indicates that metformin does not significantly affect circulating gonadotropin levels in reproductive-age women with PCOS.