The clinical importance of diabetes lies not only in hyperglycemia but also in its long-term complications, which affect multiple organ systems. Chronic hyperglycemia leads to microvascular complications such as diabetic retinopathy, nephropathy, and neuropathy, as well as macrovascular complications including coronary artery disease, stroke, and peripheral arterial disease. Acute complications like diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS) are medical emergencies requiring prompt management. Internal medicine focuses on early diagnosis, glycemic control, lifestyle modifications, pharmacotherapy (oral agents and insulin), and regular monitoring to prevent or delay complications. Comprehensive management also involves control of blood pressure, lipid levels, and screening for cardiovascular and renal disease.