Metformin Use and Risk of Delirium in Older Adults with Type 2 Diabetes

Objective: Delirium is a precursor and risk factor for dementia, emphasizing the urgency of effective prevention and management strategies in older adults with type 2 diabetes mellitus (T2DM). Identifying long-term, safe, and effective medications to prevent diabetes-related delirium is crucial due to its significant impact on this population. This study aimed to evaluate the protective effects of metformin against delirium in older adults with T2DM, using a competing risk analysis of death to provide a more accurate assessment. Research Design and Methods: Metformin users were compared to a cohort of non-users. Multivariable Cox regression and Fine and Gray methods were used to assess the risk of delirium and mortality. Results: Our study included 66,568 metformin users and 66,568 non-users, matched by propensity score. The use of metformin was associated with a significantly lower risk of delirium, with adjusted hazard ratios (aHRs) ranging from 0.77 to 0.81. A dose-response relationship was observed, indicating that higher cumulative and daily doses of metformin were associated with greater reductions in delirium risk. Conclusion: Metformin use is associated with a reduced risk of delirium in older adults with T2DM, with higher doses offering greater protection.