Diabetes mellitus is a complex chronic disease associated with an absolute insulin deficiency in type1 diabetes and a progressive deterioration of b-cell function in type 2 diabetes. The pathophysiology of type 2 diabetes includes not only the classical insulin resistance in muscle and liver and progressive b-cell failure but also accelerated lipolysis, incretin deficiency/resistance, hyperglucagonemia, renal increased glucose reabsorption, and brain insulin resistance. Finally, hyperglycemia in both type 1 and 2 diabetes results from an absolute or relative deficit in the pancreatic b -cell mass.