Metformin Use and Risk of Glaucoma: A Systematic Review and Meta-Analysis
Abstract
Topic: To evaluate whether metformin use is associated with a reduced risk of developing glaucoma.
Clinical relevance: Glaucoma is a leading cause of irreversible blindness worldwide. Identifying systemic medications that may modify glaucoma risk could have important implications for prevention strategies in patients with diabetes, a population frequently treated with metformin.
Methods: This systematic review and meta-analysis of observational cohort studies, registered on PROSPERO (CRD420250655975), was done through PubMed, Scopus, Web of Science, and Google Scholar until June 16, 2025. Eligible studies compared glaucoma incidence among metformin users versus nonusers or users of other antidiabetic drugs (ADDs). Risk of bias was assessed using the Newcastle-Ottawa Scale. Binary outcomes were pooled using random-effects models to calculate odds ratios (ORs), and time-to-event outcomes were synthesized using hazard ratios (HRs). Subgroup analyses explored confounder adjustment methods and comparator types. Certainty of evidence was graded using GRADE framework.
Results: Twelve retrospective cohort studies (n = 1,247,325; 732,423 metformin users; 513,292 controls) were included. The pooled crude OR showed no association between metformin use and glaucoma risk (OR = 0.96; 95% CI, 0.87-1.06; I² = 79.14%; low certainty). A leave-one-out sensitivity analysis excluding a study with a nonmetformin active comparator resulted in a modest but significant reduction in risk (OR = 0.92;…
How strong is the evidence?
Evidence Hub reads this as a meta-analysis, done in people. Its evidence level is 1 of 5 (Highest · pooled evidence). Pooled evidence from several studies sits at the top of the evidence pyramid. Reported size: 1,247,325 participants or records.
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