There are various reasons for low blood glucose, mainly including too much insulin, drugs, glucose metabolizing enzyme deficiency and reactive hypoglycemia. 1. Excessive insulin: overuse of exogenous insulin, insulinoma, islet cell hyperplasia, and so on. 2. Drugs: common hypoglycemic drugs, such as glibenclamide, glipizide and other sulfonylureas, improper use can cause hypoglycemic reactions. Quinine, haloperidol, salicylates and other drugs are also associated with the occurrence of hypoglycemia. 3. Glucose metabolizing enzyme deficiency: impaired glucose metabolism caused by liver disease and glycogen accumulation disorder may cause hypoglycemia. 4. Reactive hypoglycemia: Reactive hypoglycemia is mainly caused by prolonged fasting and intense exercise. It is recommended to consult a doctor in time to clarify the cause of low blood glucose and follow the doctor’s instructions to standardize the treatment.