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.