Metformin linked to lower risk of dementia and death in obese patients

Use of the diabetes drug metformin appears to be linked to reduced risk of dementia and death in obese patients, researchers reported on August 6, 2025 in Diabetes, Obesity and Metabolism.

As background, the authors noted, “Metformin, a first-line medication for Type 2 diabetes (T2D), has been suggested to reduce dementia risk. We investigated whether metformin use was associated with lower long-term incidence of dementia and all-cause mortality in obese patients.”

The investigators extracted and analyzed electronic health record data from the TriNetX network.

They categorized 452,777 subjects into four BMI (body mass index) groups (25–29.9, 30–34.9, 35–39.9 and over 40). For each BMI group, they compared data from subjects who had been prescribed metformin with matched controls who had not received the drug.

The endpoints of the study were incidence of dementia and all-cause mortality over a 10-year follow-up period.

They identified 35,784 cases of dementia and 76,048 deaths in the 10-year follow-up period.

They found significant benefits for subjects treated with metformin across all categories of overweight, obesity, and severe obesity, with 8–12% lower risks of dementia and 26–28% lower risks of death compared to untreated subjects.

The authors concluded, “In this large, multi-centre cohort study, metformin use was associated with reduced risks of dementia and all-cause mortality in obese patients. The protective effect was observed across all BMI groups, with variations noted by population. These findings support the potential of metformin in lowering dementia risk in patients with obesity. Further studies are needed to explore the underlying mechanisms.”

“Although our study results are promising for metformin’s effects on dementia and mortality, further research is required to explore the mechanisms involved,” added co-corresponding author Chiehfeng Chen, MD, PhD professor of medicine at Taipai Medical University in Taiwan.