Hypoglycemia is the most common and most important complication in the treatment of diabetes. A series of symptoms of sympathetic excitation and central nervous system dysfunction can occur during hypoglycemic episodes, and coma can occur in severe cases. Persistent severe hypoglycemia will lead to irreversible brain damage and even death. Thus, hypoglycemia must be treated urgently. Although diabetes is a group of hyperglycemic syndromes caused by different reasons, hypoglycemia often occurs during the treatment of diabetes, especially after the use of insulin in type 1 diabetes. The common causes and etiology of hypoglycemia are briefly described as follows: 1. After insulin therapy: Improper use of insulin is the main cause of hypoglycemia, such as excessive insulin dose or failure to reduce insulin dosage when physical activity increases; improper ratio of long- to short-acting insulin when injecting mixed insulin; failure to eat on time or reduced meal quantity after insulin injection for some reasons; improper injection site and Inadequate depth and malabsorption of insulin; intensive insulin treatment; delayed insulin excretion in diabetic nephropathy and renal insufficiency, when insulin dosage should be reduced or discontinued, otherwise it is easy to cause hypoglycemia. 2, oral hypoglycemic drugs later: all sulfonylurea oral hypoglycemic drugs can cause hypoglycemia, including chlorosulfonylurea because of the half-life of up to 35 hours, very easy to accumulate in the body and cause hypoglycemia, is rarely used in clinical practice. Glibenclamide (euglycemia) also often causes hypoglycemia because of its long and persistent hypoglycemic effect, especially in renal insufficiency and elderly patients, so it is recommended that elderly people over 60 years old should not use euglycemia. 3.After treatment with other drugs: salicylates, angiotensin-converting enzyme inhibitors, B-blockers, phenytoin sodium, sulfonamides and tetracycline, etc. can cause hypoglycemia. 4.Decrease in food and malabsorption: Decrease in food or malabsorption of digestive system lesions, without timely adjustment of medication, can cause hypoglycemia. Excessive exercise: When normal people exercise, catecholamines and glucagon are released to increase glycogenolysis and promote gluconeogenesis; at the same time, catecholamines and other neurohumoral regulation can still inhibit insulin secretion, thus keeping blood sugar stable. In the case of insulin-treated diabetic patients, the insulin concentration not only cannot be reduced accordingly during exercise, but also increases due to accelerated blood flow and increased subcutaneous absorption, and the blood concentration rises, resulting in hypoglycemia. 6, alcohol consumption: ethanol can hinder the hepatic glycogen isogenesis, resulting in hypoglycemia. 7, hepatogenic diabetes: the patient’s liver is severely damaged and the regulation of glucose metabolism is weakened, which can be manifested as postprandial hyperglycemia and fasting hypoglycemia. 8. Newborn babies delivered by diabetic pregnant women: It may be related to the long-term hyperglycemic environment stimulating the proliferation of fetal islet cells. Understand the many reasons for the occurrence of hypoglycemia, we should take different measures to avoid it for different reasons. At the same time, learn to rescue. First of all, learn to help yourself: always have candy around, and once hypoglycemia occurs, immediately take sugar water or carbohydrate-based food by mouth and actively go to a nearby hospital. To avoid adverse consequences.