Low blood sugar is not a good thing. Low blood sugar does not mean that diabetes is far away from you, on the contrary, it may also be a sign that you are already in the ranks of pre-diabetes. A patient in his 50s was recently seen, and in the past two months, he often experienced palpitations, hand tremors, sweating, fatigue, hunger pangs and other low blood sugar symptoms, and would feel better after eating. The frequency of episodes was irregular, mostly before meals and bedtime. He ate frequently for fear of hypoglycemic reactions, and his weight increased by 5 kg in 2 months. When he arrived at the hospital, we gave him a glucose tolerance test, which showed hypoglycemia (IGT) and pre-diabetes. The manifestations of hypoglycemia are diverse and vary greatly between individuals. When blood sugar is lower than 2.8mmol/l, it is called biochemical hypoglycemia; when sympathetic excitement symptoms such as panic, hand trembling, sweating, hunger, or central nervous system symptoms such as dullness, talkative, answering, mental agitation, unconsciousness, coma, etc. occur, it is called hypoglycemic reaction; but when blood sugar is lower than 2.8mmol/l, it causes various uncomfortable hypoglycemic reactions at the same time, it is called Hypoglycemia. Normal people do not feel anything when their fasting blood sugar fluctuates from 3.9 to 6.1mmol/L. Due to the strong self-regulation ability of the body, ordinary people generally do not have hypoglycemia. Hypoglycemia is very harmful, in the state of hypoglycemia, dizziness and unconsciousness may occur, which may easily lead to fall injury and other accidents and cause accidental injury; hypoglycemia is not handled early and progresses into serious hypoglycemia, which may easily cause cardiovascular accidents and induce complications such as arrhythmia, angina pectoris, heart attack and stroke; the only energy source of human brain tissue is blood sugar, so hypoglycemia has the greatest impact on the organism If not treated in time, it may lead to irreversible damage of brain tissue and even death in a short time. Paying attention to the detection and prevention of hypoglycemia is of great significance to reduce the occurrence of adverse events. Certain patients with type 2 diabetes firstly have hypoglycemic reactions in the early stage of the disease, which is due to the fact that patients with type 2 diabetes still have strong insulin secretion ability in the early stage, only the secretion response is sluggish and the peak of secretion is delayed, after meals, the secretion of insulin is less than normal at the beginning, which makes the blood glucose increase, and the secretion of insulin increases significantly under the stimulation of high blood glucose, 3~4 hours after meals, in the body absorbed from the intestine Glucose has been mostly consumed, and the insulin in the body at this time appears to be relatively too much, thus causing a hypoglycemic reaction. However, because patients are always alert to high blood sugar and complacent to low blood sugar, they miss the golden time to correct blood sugar. Moreover, because of the feeling of hunger, the frequency of eating will increase, leading to weight gain and metabolic syndrome. Once checked out it is diabetes. For this group of people, we usually advise them to control mainly through diet. It is recommended to adopt a split meal system, such as 3 meals a day to 6 meals a day, but to ensure that the total intake remains the same. Besides diabetes, there are many other diseases that may also cause hypoglycemia. Such as abnormal hormone secretion of endocrine system, pancreatic islet beta cell tumor, digestive system disease, kidney disease, tumor, etc., while poor blood supply to heart, cerebrovascular disease, autonomic neuropathy, etc. may also cause similar hypoglycemic reactions such as panic, sweating and hunger. Therefore, once frequent hypoglycemic reactions occur, it is necessary to consult a doctor promptly, actively search for the cause of the disease and carry out cause-specific treatment.