A new large study suggests that a group of diabetes medications called GLP-1 receptor agonists may be better than metformin at protecting the brain and lowering the risk of dementia in people with type 2 diabetes.
This research was published in BMJ Open Diabetes Research & Care.
Both GLP-1 drugs and metformin are commonly used to manage blood sugar in type 2 diabetes. Past studies have shown that they may also protect the brain. But this is the first big real-world study to compare how well each drug helps reduce the risk of developing dementia.
Researchers looked at the health records of over 174,000 people with type 2 diabetes, half of whom took GLP-1 drugs and the other half metformin. All participants used the medication for at least six months. The average age was 58.
The results were striking. About 2.5% of people taking GLP-1 drugs developed dementia, compared to nearly 5% of those on metformin. That means those on GLP-1 drugs had a 10% lower overall risk of dementia.
They also had a 12% lower risk of Alzheimer’s disease and a 25% lower risk of non-vascular dementia, which is not related to problems with blood flow in the brain.
The study also found that GLP-1 drugs helped people live longer. Nearly 5% of people taking them died during the study period, compared to almost 9% of those taking metformin.
Why might GLP-1 drugs work better? The researchers explain that both GLP-1 drugs and metformin have brain-protecting effects. They reduce inflammation and oxidative stress, improve how the body uses insulin, and help keep blood vessels in the brain healthy.
But GLP-1 drugs have an added benefit—they can cross into the brain and act directly on the central nervous system. This might explain why they seem to offer more protection.
Interestingly, the strongest benefits were seen in people over 60, in women, and in those who were white.
However, the study has limits. It was observational, meaning it only looked at patterns in existing medical records. It can’t prove cause and effect. And because dementia takes a long time to develop, longer studies are still needed.
Still, the results suggest that GLP-1 drugs might one day become a first-line treatment for type 2 diabetes—not just to control blood sugar, but also to protect the brain.
With type 2 diabetes linked to a 70% higher risk of dementia, this could be a big step toward preventing cognitive problems in millions of people.
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The study is published in BMJ Open Diabetes Research & Care.
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