The category of type 2 diabetes drugs known as sulfonylureas may raise the risk for dementia, while thiazolidinediones (TZDs) may lower the risk for dementia, according to a new study published in the journal BMJ Open Diabetes Research and Care.
Dementia, or advanced cognitive impairment, is connected to both type 1 and type 2 diabetes. Studies have shown that for people with type 1 diabetes, both high and low glucose levels are linked to a higher risk for dementia. When it comes to type 2 diabetes, having poorly controlled blood glucose is especially linked to a higher dementia risk. In addition to blood glucose control, lifestyle factors may play a role in preventing dementia — including getting enough physical activity and following a diet that’s high in antioxidants and fiber while avoiding inflammatory foods.
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For the latest study, researchers looked at the risk of developing dementia in 559,106 U.S. military veterans with type 2 diabetes. All study participants were at least 60 years old at the time they started taking a diabetes drug for the first time, and the average age of all participants was 65.7. To be included in the study, participants had to start taking either metformin, a sulfonylurea (such as glyburide, glipizide, or glimepiride), or a TZD (such as pioglitazone) — or two of these drugs — between January 2001 and December 2017, and to take their prescribed drug or drugs for at least a year. The average follow-up period in which new cases of dementia were recorded was 6.8 years.
Sulfonylureas linked to higher dementia risk
The overall rate of new cases of dementia during the follow-up period was 8.2 cases for every 1,000 years lived. Using participants who took metformin as a baseline comparison, the researchers found that participants who took a TZD for at least a year were 22% less likely to develop dementia. Those who took both metformin and a TZD were 11% less likely to develop dementia that those who took metformin alone. Participants who took a sulfonylurea, on the other hand, were 12% more likely to develop dementia.
The researchers also found that the risk for a heart attack or atherosclerosis (buildup of a fatty substance called plaque inside your arteries) was higher in sulfonylurea users and lower in TZD users, indicating that cardiovascular effects might be responsible for the higher or lower dementia risk linked to these drugs. The drugs’ effect on blood glucose control did not appear to potentially explain participants’ dementia risk, since there were no significant differences in A1C (a measure of long-term blood glucose control) in each of the drug treatment groups.
“Our findings provide additional information to aid clinicians’ selection of [diabetes drugs] for patients with mild or moderate [type 2 diabetes] and at high risk of dementia,” the researchers wrote. “Given the predominately white and male [veteran] population, future studies among more diverse populations are needed to confirm the findings.”
Want to learn more about maintaining cognitive health with diabetes? Read “Nine Tips to Keep Your Memory With Diabetes,” “Keeping Your Brain Strong With Diabetes” and “Memory Fitness: How to Get It, How to Keep It.”