Diabetes mellitus is a group of metabolic diseases characterized by high blood glucose levels resulting from defects in insulin production or insulin action. The main types are type 1 diabetes, type 2 diabetes, and gestational diabetes. The long-term complications of diabetes include damage to various organs such as the eyes, kidneys, nerves, and heart. Management of diabetes focuses on lifestyle modifications like diet and exercise as well as medication including oral hypoglycemic drugs and insulin therapy to control blood glucose levels and minimize health risks.