Why metformin works to lower blood sugar levels in humans
Turns out, metformin—the diabetes drug that's been around for over 60 years—actually lowers blood sugar by acting on the brain as well as the body.
A new study from Baylor College of Medicine (published September 18, 2025) found that metformin targets a specific brain region called the VMH and blocks a protein called Rap1.
When this protein was switched off in mice, metformin stopped working to lower their blood sugar.
Research could lead to new diabetes treatments
Researchers also showed that the brain responds to much lower levels of metformin than the liver or gut, and that introducing the drug directly into the brain can affect blood sugar levels in mice.
This means your brain is surprisingly sensitive to this common diabetes med.
The discovery could lead to smarter diabetes treatments that work through the brain—and it even hints at why some think metformin might help slow down aging or boost lifespan.
More research in humans could open up new ways to treat both diabetes and age-related diseases.