Mulberry (Monet alba) leaves have long been used to feed silkworm and known as traditional Chinese medicine. Many researchers reported it can cure and prevent diabetes. The active compounds, including 1-deoxynojirimycin (DNJ), a potent inhibitor of mammalian a-Clucosidase, were found in leaves and stein barks of mulberry tree. DNJ have long been studied because of their antidiabetic effect. This review article describes DNJ about distributions in Mulberry tree and relationship with diabetes mellitus.