We may finally understand how metformin lowers blood sugar, animal study finds

An illustration of bacteria in the gut.

Since the 1990s, doctors have prescribed the drug metformin to treat type 2 diabetes, but scientists didn't fully understand how it worked.

Now, new research fills in one piece of the puzzle: Metformin triggers the body to expel glucose from the bloodstream into the intestines, where bacteria feed on the carbohydrate to make compounds that may help control blood sugar levels.