More than 2 years of metformin therapy, compared with no metformin use, was associated with a lower incidence of neurodegenerative disease among older adults with type 2 diabetes who were US veterans, according to a study published online in BMJ Open.
The retrospective cohort study used data from electronic medical records to examine the effect of metformin exposure duration on the development of neurodegenerative disease in 5528 US veterans described as elderly over a median follow-up period of 5.2 years.
While metformin exposure in the first 2 years showed no significant influence on the risk of developing neurodegenerative disease, longer exposure did.
“We found that metformin treatments at both 2–4 years and more than 4 years were shown to have significant risk reduction of incidence of neurodegenerative disease in patients with type 2 diabetes mellitus than in patients in nonmetformin treatment group during the study period,” researchers wrote. “Similar results were shown in the analysis on subtypes of outcome, dementia.”
For Parkinson disease and Alzheimer disease, incidence was reduced only with more than 4 years of metformin exposure. The protective benefit of metformin was not significant for mild cognitive impairment, however—likely because of the limited number of participants with the condition, researchers explained.
“We need to conduct a study with more representative population using more robust method for causal inferences,” researchers wrote. “Further investigation into the mechanism involved is needed along with randomized trials to confirm a potential neuroprotective effect of metformin.”—Jolynn Tumolo