Acarbose is a drug used to treat type 2 diabetes mellitus. It is sold in Europe under the brand name Glucobay® (Bayer AG), in North America as Precose® (Bayer AG), and in Canada as Prandase® (Bayer AG). It is an inhibitor of alpha glucosidase, an enteric enzyme that releases glucose from larger carbohydrates. The main side-effect is loose stool or diarrhea, which limits its use. It is a moderately effective anti-diabetic drug.