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TOPLINE:

During a 10-year follow-up, metformin use was associated with significantly lower risks for both dementia and all-cause mortality in patients with overweight or obesity.

METHODOLOGY:

• Metformin, the most widely prescribed glucose-lowering treatment, is linked to a reduced risk for dementia in patients with diabetes; however, its effect on the incidence of dementia among individuals with obesity has not been established with real-world data.
• Researchers analyzed data from adults with varying degrees of overweight and obesity from a popular global health research network to investigate the link between metformin and the long-term incidence of dementia and all-cause mortality.
• Adults prescribed metformin at least twice, with a minimum of 6 months between prescriptions, were compared with propensity score-matched control individuals who did not receive the medication; the follow-up period was 10 years.
• In both the metformin and control groups, the number of participants was 132,920 for BMI 25-29.9; 142,723 for BMI 30-34.9; 94,402 for BMI 35-39.9; and 82,732 for BMI ≥ 40.
• The primary outcomes measured were dementia and all-cause mortality.

TAKEAWAY:

• After 10 years of follow-up, metformin users had a significantly lower risk for dementia across BMI categories than control individuals (hazard ratio [HR] for BMI, 25-29.9, 0.875 [95% CI, 0.848-0.904]; HR for BMI, 30-34.9, 0.917 [95% CI, 0.885-0.951]; HR for BMI, 35-39.9, 0.878 [95% CI, 0.834-0.924]; and HR for BMI, ≥ 40, 0.891 [95% CI, 0.834-0.953]).
• All-cause mortality was also reduced in metformin users, with HRs ranging from 0.717 to 0.743 across all BMI categories.
• Age-stratified analysis showed that among patients younger than 65 years, metformin may significantly reduce the risk for dementia for those with BMIs of 30-39.9.

IN PRACTICE:

“Regarding the relationship between metformin, dementia, and all-cause mortality, our findings suggest that metformin not only has a protective effect against dementia but also significantly reduces all-cause mortality. Since dementia is a contributing factor to all-cause mortality, this may partially explain metformin’s effect,” the authors of the study wrote.

SOURCE:

This study was led by Yu-Liang Lin, MD, Taipei Medical University, Taipei, Taiwan. It was published online on August 6, 2025, in Diabetes, Obesity and Metabolism.

LIMITATIONS:

The use of standard diagnostic codes for dementia diagnosis may have contributed to potential misclassification in real-world settings. Due to confidentiality agreements, researchers could not access raw and individualized data, and treatment escalation sequences were unknown. The effects of changes in medication regimens after the second metformin prescription could not be determined.

DISCLOSURES:

This study did not report any source of funding. The authors declared having no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.