In clinical practice, intravenous insulin is mainly used in the treatment of diabetic ketoacidosis, hyperglycemic hyperosmolar coma, to achieve rapid reduction of blood glucose. Insulin injection is mainly used for type 1 diabetes mellitus, gestational diabetes mellitus, or type 2 diabetes mellitus with severe infections, trauma, major surgery and other severe stress situations, as well as the combination of cardiovascular and cerebral vascular complications, renal or retinopathy. Insulin is usually given by subcutaneous injection. Intravenous injection is mainly used in the treatment of diabetic ketoacidosis and hyperglycemic hyperosmolar coma, which can effectively and rapidly reduce blood glucose. Common adverse effects of insulin use include hypoglycemia, mild edema, blurred vision, allergic reactions, and lipoatrophy or hyperplasia. Insulin should be used strictly under medical supervision.