Metformin Use for Type 2 Diabetes Does Not Affect Cognitive Test Performance

Investigators did not link metformin use with cognitive test performance over time.

In patients with type 2 diabetes (T2D), metformin use is not associated with cognitive test performance, according to study results published in The International Journal of Geriatric Psychiatry.

However, the results did indicate that metformin use was associated with incident mild cognitive impairment diagnosis. Other oral medications for diabetes and insulin also had this association.

The study included participants with T2D with no cognitive impairment at baseline enrolled in the Mayo Clinic Study of Aging (n=508). The researchers investigated the association between treatment type and cognitive test z scores.

The researchers did not find an association between metformin use and cognitive test performance after adjusting for age, sex, education, body mass index, APOE ε4, insulin treatment, medical comorbidities, number of medications, duration of diabetes, and propensity score.

Metformin was associated with an increased risk for mild cognitive impairment (subhazard ratio (SHR) 2.75; 95% CI, 1.64-4.63; P <.001). Other oral medications (SHR 1.96; 95% CI, 1.19-3.25; P =.009) and insulin use (SHR 3.17; 95% CI, 1.27-7.92; P =.014) were also associated with an increased risk for mild cognitive impairment.

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“Future research should work to understand if and how this association may be moderated by vitamin B12, and whether dose or duration of metformin use impacts the associations,” the researchers wrote.


Wennberg AMV, Hagen CE, Edwards K, et al. Association of antidiabetic medication use, cognitive decline, and risk of cognitive impairment in older people with type 2 diabetes: results from the population-based Mayo Clinic Study of Aging [published online June 5, 2018]. Int J Geriatr Psychiatry. doi:10.1002/gps.4900