NEW DELHI: Cheap, effective and widely trusted, metformin has long been the first choice for treating type 2 diabetes. Now, scientists say the drug works in a way few had imagined — by acting directly on the brain.A study published in Science Advances by Baylor College of Medicine has uncovered a hidden brain pathway that helps explain how metformin lowers blood sugar, offering fresh insight into a medicine used for over six decades.For years, metformin was believed to act mainly on the liver and gut. The new research shows it also works through the ventromedial hypothalamus — a small but crucial brain region that controls hunger, energy use and glucose balance.The drug switches off a protein called Rap1 and activates nerve cells that regulate blood sugar, effectively using the brain’s control system. When this pathway was blocked, metformin stopped working while drugs like insulin remained effective. Even tiny amounts were enough to lower blood sugar.Lead researcher Makoto Fukuda said the discovery challenges long-held assumptions. Experts said the findings add clarity, not concern.