Diabetes mellitus is a group of metabolic diseases characterized by chronic hyperglycemia resulting from defects in insulin secretion, insulin action. Different classes of diabetes mellitus type1, type2 ,gestational is summarized. It is predicted that the prevalence of DM in adults of which type2 is becoming prominent mostly in developing countries. The treatment strategies are listed and many new drugs are currently in development for treatment of diabetes including more products with new mechanisms .Drugs with application submitted for US food and Drug administration (FDA) approval and drugs currently in phase3 clinical trials are summarized.