Research conducted by scientists at Baylor College of Medicine has revealed that metformin, a widely prescribed drug for type 2 diabetes, has unexpected effects on the brain. This discovery, published in the journal Science Advances, suggests that metformin may operate through a specific brain pathway, opening avenues for new treatment strategies.
For over 60 years, metformin has primarily been recognized for its role in lowering blood glucose levels by reducing glucose production in the liver. Makoto Fukuda, a pathophysiologist at Baylor, states, “It’s been widely accepted that metformin lowers blood glucose primarily by reducing glucose output in the liver. Other studies have found that it acts through the gut.” With this recent study, researchers turned their attention to the brain, a critical regulator of whole-body glucose metabolism.
The team previously identified a protein known as Rap1, which significantly influences glucose metabolism in the brain, particularly within the ventromedial hypothalamus (VMH). In their 2025 study, experiments conducted on mice demonstrated that metformin travels to the VMH, where it reduces the activity of Rap1, thereby addressing type 2 diabetes.
In an intriguing finding, when the researchers bred mice devoid of Rap1, they observed that metformin had no effect on their diabetes-like symptoms, even while other medications remained effective. This evidence strongly supports the notion that metformin operates in the brain through a distinct mechanism compared to other diabetes treatments.
The study further examined the specific neurons affected by metformin, potentially leading to more targeted therapies in the future. Fukuda noted, “We also investigated which cells in the VMH were involved in mediating metformin’s effects,” and added, “We found that SF1 neurons are activated when metformin is introduced into the brain, suggesting they’re directly involved in the drug’s action.”
Metformin is valued not only for its effectiveness in managing type 2 diabetes but also for being safe, long-lasting, and relatively affordable. It enhances the body’s insulin sensitivity while reducing liver glucose production. With this new understanding of its brain-related mechanisms, there is potential to enhance its efficacy and broaden its application in medical treatment.
The implications of this research extend beyond diabetes management. Earlier studies have suggested that metformin may slow brain aging and improve longevity. Fukuda emphasized the significance of these findings, remarking, “This discovery changes how we think about metformin. It’s not just working in the liver or the gut; it’s also acting in the brain.” He further noted that while the liver and intestines require high concentrations of the drug to respond, the brain can react to much lower levels.
As researchers prepare to investigate these effects in human studies, there is optimism about the potential for developing more effective therapies that leverage metformin’s multifaceted action. The future may hold new methods for enhancing metformin’s impact, potentially benefitting a wider range of patients.
