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Metformin Associated with Cognitive Impairment

Sep 19, 2013

Individuals taking metformin and who have a vitamin B12 deficiency are associated with an impaired cognitive performance…. 

In a retrospective study led by Moore et al., diabetic patients taking metformin were monitored to see if they developed cognitive impairment. Those included in the analysis either came from the PRIME clinic study, or the AIBL study of aging. Patients with Alzheimer’s disease or mild cognitive impairment were included in the study, while individuals with stroke and neurodegenerative diseases were not.

Results found that patients with diabetes had more severe symptoms of cognitive impairment than those who did not have the chronic disease (adjusted odds ratio 1.51 [95% CI 1.03–2.21]). Furthermore, participants with diabetes taking metformin displayed the worse cognitive performance among all subgroups (2.23 [1.05–4.75]). Diabetic participants who took vitamin B12 and calcium supplements presented with better cognitive performance.

Researchers of the study mention that metformin’s lowering effects on cognitive performance may be tied to its lowering effect on vitamin B12 levels. This is because when vitamin B12 levels were increased via supplementation, cognitive performance was less impaired among patients.

In conclusion, it can be seen that metformin is associated with impairing cognitive performance. However, taking vitamin B12 and calcium supplements with metformin may help decrease these outcomes. Future trials will be studying the effects vitamin B12 and calcium has in the older population with diabetes who are taking metformin.

Moore EM, et al "Increased risk of cognitive impairment in patients with diabetes is associated with metformin" Diabetes Care 2013; DOI: 10.2337/dc13-0229