The majority of patients do not have typical symptoms of “high blood sugar” such as polyuria, polydipsia, polyphagia, weight loss, etc. Some patients even visit the clinic because of “low blood sugar” before meals, showing recurrent episodes of hunger before meals, panic, hand trembling, cold sweat and other symptoms of low blood sugar. The symptoms of hypoglycemia such as hunger before meals, panic, hand trembling, cold sweat, etc., can be relieved after eating. Diabetes is characterized by high blood sugar, how can it be related to hypoglycemia? Under normal physiological conditions, elevated blood sugar after eating stimulates insulin secretion, and the elevated insulin will quickly shut down the endogenous glucose production in the liver, and also promote the uptake and utilization of glucose by peripheral tissues, so the blood sugar will not rise too high after meals, and insulin secretion reaches a peak 30 minutes or 60 minutes after eating, which is generally 5 to 10 times the basal level, and insulin level starts to fall 2 hours after meals, and 3 to 4 minutes after meals. The insulin level starts to decline 2 hours after meal, and insulin basically returns to the pre-meal level 3~4 hours after meal, so hypoglycemia will not occur before meal. In some patients with type 2 diabetes, the pattern of insulin secretion changes in the early stage, and insulin secretion is not high enough 30 or 60 minutes after meal (called hyposecretion of pancreatic B cells) or although the level is high, it cannot function (called insulin resistance), resulting in a rise in blood glucose 30 or 60 minutes after meal; accompanied by a delay in the peak time of insulin secretion, 2 hours or even 3 hours after meal The insulin level is still high, while the glucose in the body is almost consumed at this time, and if the meal is not eaten in time, the performance of hypoglycemia may occur. So which people are prone to this situation? Patients with obesity, fatty liver, dyslipidemia, hypertension, high uric acid, women with previous history of polycystic ovary syndrome and gestational diabetes, all of these people belong to the high-risk group of diabetes, and the possibility of early diabetes should be highly suspected if the symptoms of pre-meal hypoglycemia appear. An extended glucose tolerance test plus insulin release test can clarify the diagnosis by taking 75g of glucose orally and measuring blood glucose and insulin at 0, 30, 60, 120, 180 and 240 minutes, respectively, and dynamically observing the changes of blood glucose and insulin to see if postprandial hyperglycemia, preprandial hypoglycemia and changes in insulin secretion pattern occur. Can preprandial hypoglycemia be prevented and treated? Patients often rely on increased food intake (such as candy, chocolate, desserts, and high-fat, high-calorie foods) to relieve hypoglycemic symptoms until they are properly diagnosed, which can exacerbate postprandial hyperglycemia and allow early diabetes to progress quickly to true diabetes. The correct approach is: the most important thing is to change the lifestyle, through diet control and proper exercise, reduce weight and increase insulin sensitivity, thus can stop or delay the onset of clinical diabetes, if there are still symptoms of hypoglycemia, you can take the method of eating less and more meals or take drugs that can slow down the absorption of carbohydrates such as acarbose during meals.