A new study suggests that metformin, a common diabetes drug, influences brain mechanisms to regulate blood sugar, opening doors for targeted treatments and new understanding of its benefits beyond glucose control.
Metformin, one of the most widely prescribed drugs for type 2 diabetes, has long been known to lower blood sugar, but the precise route it takes through the body has remained uncertain. Now, researchers led by Baylor College of Medicine say the medicine appears to act directly in the brain, adding a new layer to a drug that has been in routine use for decades.
In work published in Science Advances, the team focused on the ventromedial hypothalamus, a part of the brain involved in energy balance and glucose control, and on a protein called Rap1. They found that metformin switches down Rap1 activity in this region, which in turn helps reduce blood sugar. Previous research had already suggested that metformin’s actions are more complex than a simple liver-only effect, and that it can cross the blood-brain barrier.
The study also used diabetic mice engineered without Rap1 in that brain area. In those animals, low doses of metformin produced little benefit, while insulin and GLP-1 drugs still worked, suggesting the newly identified route is specific to metformin rather than a general feature of diabetes treatment. The researchers further reported that tiny injections of metformin directly into the brain lowered glucose despite using doses far below oral treatment levels.
According to the team, the drug’s effect depends on SF1 neurons, which were activated only when Rap1 was present. That finding strengthens the case that the brain is not just a passive bystander in metformin’s action but a central part of its mechanism. If the pathway is confirmed in further studies, it could help researchers design more targeted treatments for diabetes and may also shed light on why metformin has been linked to possible benefits beyond blood sugar control, including brain ageing.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
