Impact of metformin use on neurocognitive functions in older people with diabetes mellitus: A systematic review and meta-analysis

Introduction: Metformin is a widely prescribed drug for managing diabetes mellitus. Recent research has investigated its potential impact on cognitive function among individuals aged 60 years and older—a population that is steadily increasing and often exhibits cognitive impairments associated with aging and diabetes mellitus. Objective: This study aimed to evaluate the impact of metformin use on cognitive functions in older adults with diabetes mellitus through a meta-analysis. Methods: A systematic review and meta-analysis were conducted in accordance with PRISMA guidelines, utilizing the Embase, LILACS, PubMed, Scopus, and Web of Science databases. The review protocol was registered in PROSPERO (CRD42024624045). Results: Thirteen articles met the eligibility criteria for inclusion in this systematic review, of which five provided sufficient data for meta-analysis. The findings indicate that metformin has a small but positive effect on overall cognitive function in older adults. Additionally, the meta-analysis demonstrated low heterogeneity (49.6%) and a low risk of bias (p > 0.05). Conclusion: The results suggest that metformin not only improves glycemic levels, but may also have a protective effect on the overall cognitive function of older people with diabetes mellitus.