SLU scientists receive grant to investigate link between diabetes drug and dementia risk

Saint Louis University researchers have received a $443,636 grant from the National Institute on Aging to investigate the relationship between the diabetes drug Metformin and dementia risk.

Jeffrey Scherrer, Ph.D., professor and research director in the department of family and community medicine at Saint Louis University, said this is the first study of metformin use and dementia risk in patients from the U.S. and the first to include a large proportion of African American and Hispanic patients.

"The study uses real world patient data from Veterans Administration (VA) and Kaiser Permanente Washington (KPW) to determine the potential protective effect of metformin, a front line anti-diabetic medication, on risk of dementia," Scherrer said.

The retrospective cohort study uses electronic health record data from the VA and KPW. The researchers identified about 20,000 eligible patients from KPW data and about 100,000 from VA data. Eligible patients are 50 years of age or older, have diabetes and are free of any dementia diagnosis at the start of the study.

Both the VA and KPW were used because the organizations support large cohort studies by maintaining extensive electronic health record data covering 15 to 20 years of patient visits. Such large data bases containing patient demographics, diagnosis and procedure codes, prescription fills and lab results can be used to identify rare outcomes, including incident dementia in patients taking medication for diabetes.

Researchers want to first determine if there is a reduced risk of dementia in patients starting metformin for Type 2 diabetes versus those starting a sulfonylurea, one of a group of medicines used in the management of Type 2 diabetes.

The team will then compare the risk of dementia in patients starting metformin versus patients who delay pharmacologic treatment of diabetes. Researchers will also study whether the association between metformin and reduced risk of dementia differs in younger versus older patients (those aged 50-65 versus those more than 65 years of age) and by gender.

Exploratory analysis will be conducted to see if the risk of dementia changes by metformin dose and duration of use.

Analyses will first be computed in the VA patient data and replicated in a KPW patient sample.

"The VA and KPW patient groups have very different clinical and demographic characteristics. Replicating results in these two patient groups will strengthen our study conclusions," Scherrer said. "By establishing if metformin independently reduces risk of dementia and if that risk varies by age groups and gender, the results will inform patient-provider discussions on when to initiate, and whether to remain on metformin, in patients with type 2 diabetes."