St. Louis, MO—Use of metformin for type 2 diabetes (T2DM) significantly reduces the risk of dementia among men in certain racial and age groups, especially those who are aged 50 years and older and African American, according to a large observational cohort study.

The study, published in the Annals of Family Medicine, included data from 73,500 patients who received care through the Veterans’ Health Administration from 2000 to 2015. While all participants were diabetes- and dementia-free at baseline, the patients subsequently developed T2DM and began treatment with either metformin or sulfonylurea.

“African American patients are more likely to experience cognitive decline after type 2 diabetes mellitus onset than white patients,” write the Saint Louis University School of Medicine–led authors. “Metformin use has been associated with a lower risk of dementia compared with sulfonylureas. Evidence for whether this association differs by race is sparse.”

In fact, the article notes that T2DM is almost twice as prevalent among African Americans as non-Hispanic whites, with an age-adjusted prevalence of 13.4% in African Americans and 7.3% in whites. In addition, according to the study, African American patients on average have worse glycemic control and more diabetes-related complications than white patients.

Especially troubling, the authors point out, “Diabetes is a risk factor for dementia, and African Americans have nearly twice the incidence of dementia as whites. This disparity is greater in patients aged 55 to 65 years compared with older patients. The prevalence of dementia in patients with T2DM is 10% to 18% greater in African American patients compared with white patients. Results from the Atherosclerosis Risk in Communities study indicate that African American participants with T2DM had a 41% decrease in cognitive test scores over a period of 14 years, whereas white participants experienced no decrease.”

Researchers reported that, after controlling for confounding, among patients aged 50 years and older, metformin versus sulfonylurea use was associated with a significantly lower risk of dementia; however, in African American patients (hazard ratio [HR] = 0.73; 95% CI, 0.6-0.89) although not white patients (HR = 0.96; 95% CI, 0.9-1.03).

The study determined that the strongest magnitude of association between metformin and dementia was observed among African American patients aged 50 to 64 years (HR = 0.6; 95% CI, 0.45-0.81).

In addition, among veterans aged 65 to 74 years, metformin was significantly associated with lower risk of dementia in both races, although the drug was not associated with dementia in patients aged 74 years and older.

“Metformin vs. sulfonylurea initiation was associated with a substantially lower risk of dementia among younger African American patients,” study authors concluded. “These results may point to a novel approach for reducing the risk of dementia in African Americans with type 2 diabetes mellitus.”

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