New Brain Mechanism Reveals How Metformin Lowers Blood Sugar

Scientists discovered that metformin lowers blood sugar not only via the liver and gut but also by acting in the brain. In mice, metformin inhibits Rap1 in the ventromedial hypothalamus, activating SF1 neurons and reducing glucose; surprisingly small brain doses produced effects, and removing Rap1 from VMH abolished metformin’s action, illustrating a distinct brain pathway that could enable lower-dose, brain-targeted diabetes therapies in the future.