Metformin decreased dementia risk in older adults with type 2 diabetes mellitus

Type 2 diabetes is a risk factor for dementia. Researchers analysed data from Taiwan's National Health Insurance Research Database (NHIRD) to assess whether treatment for type 2 diabetes affected dementia risk in adults ≥60 years old with type 2 diabetes mellitus on treatment. Diabetes diagnosis, type of anti-diabetic medication used, and dementia classification were based on NHIRD records.

Among 14,558 participants, the average age at diabetes diagnosis was 71 years for both metformin users and non-users. Nine percent of metformin users and 15% of non-metformin users developed dementia over 5 years. The most prevalent non-metformin medications included sulfonylureas, alpha-glucosidase inhibitors, dipeptidyl peptidase-4 inhibitors, and insulin.

Metformin use decreased the risk for dementia by 34% in a dose-response relationship after adjustment for covariates compared with nonuse of metformin. This decreased risk for dementia for metformin users remained significant after additional analyses.

The results of this study suggest that metformin can decrease dementia risk in older adults with type 2 diabetes mellitus. The authors propose that metformin's ability to cross the blood–brain barrier may be a contributing mechanism.