A large-scale study published in the Diabetes Care has revealed that metformin, a widely used drug for managing type 2 diabetes (T2D), may offer a significant protective effect against delirium in older adults. Delirium, a sudden change in mental state often marked by confusion and disorientation, is not only distressing but is also a known risk factor for future dementia, especially among individuals with T2D.

In a detailed analysis involving 133,136 older adults with T2D, researchers compared 66,568 metformin users with an equal number of nonusers using propensity score matching to ensure a fair comparison. 
Metformin use was associated with a 19% to 23% lower risk of developing delirium. Furthermore, the protective benefit of the drug appeared to increase with both higher daily doses and cumulative exposure, indicating a clear dose-response relationship.

Researchers used multivariable Cox regression and the Fine and Gray method; an advanced statistical approach that accounts for the risk of dying before experiencing delirium, to confirm the robustness of their findings.