The causes of low blood sugar include insufficient intake or too much insulin release too fast. The common causes of low blood sugar are: 1. People with gastrointestinal diseases cannot eat normally or excrete too much, which leads to low blood sugar due to insufficient long-term food intake. 2. Because alcohol can inhibit the output of liver glycogen, drinking a lot of alcohol without eating main food can easily lead to low blood sugar. 3. 4.Inappropriate use of insulin or hypoglycemic drugs in diabetic patients leads to excessive drop of blood glucose. 5.Some malignant tumors can secrete insulin-like substances leading to drop of blood glucose. 6.The tumor of insulin tumor can easily lead to abnormal secretion of insulin and then to recurrent hypoglycemia. 7.Liver and kidney insufficiency, anterior pituitary gland and hyperaldosteronism can cause organic drop of blood glucose. The organic blood glucose drop can be caused by liver and kidney insufficiency, anterior pituitary and adrenal cortical hypoplasia, etc. The main hazards of low blood sugar are: severe hypoglycemia can lead to brain cell damage, affect memory, cause decreased responsiveness, and in severe cases can lead to mental and behavioral abnormalities and irreversible brain death. For diabetic patients, hypoglycemia can be followed by rebound hyperglycemia, which makes it difficult to lower glucose treatment, and repeated hypoglycemia can easily cause psychological fear and shadow. Therefore, when low blood sugar occurs, it should be dealt with promptly and the cause should be found to prevent serious health hazards from occurring.