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 (T2D). Identifying long-term, safe, and effective medications to prevent diabetes-related delirium is crucial because of its significant impact on this population. This study aimed to evaluate the protective effects of metformin against delirium in older adults with T2D, using a competing risk analysis of death to provide a more accurate assessment. RESEARCH DESIGN AND METHODS Metformin users were compared with a cohort of nonusers. 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 nonusers, matched by propensity score. The use of metformin was associated with a significantly lower risk of delirium, with adjusted hazard ratios 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. CONCLUSIONS Metformin use is associated with a reduced risk of delirium in older adults with T2D, with higher doses offering greater protection.