There are many kinds of oral hypoglycemic drugs commonly used in clinical practice, and the duration of oral hypoglycemic drugs is related to the mechanism of action of the drugs, which are mainly divided into the following categories: 1. insulin stimulants, commonly used insulin stimulants include sulfonylurea hypoglycemic drugs and glargine hypoglycemic drugs. Insulin stimulants work by promoting the secretion of insulin and are only suitable for patients with type 2 diabetes whose pancreatic beta cells are still functional. Insulin stimulants need to be taken 10-20 minutes before meals, so that the peak of insulin secretion after meals is consistent with the peak of blood glucose, and the glucose-lowering effect can be given full play. 2.Biguanide preparations, by promoting the use of peripheral glucose, promote anaerobic enzymes to play a role. Biguanide preparations can easily lead to upper abdominal discomfort, nausea and other gastrointestinal symptoms, so biguanide preparations can be taken immediately after meals, which can effectively lower glucose and also reduce gastrointestinal side effects.3. Glycosidase inhibitors, which slow down carbohydrate absorption by inhibiting intestinal glycosidase activity, achieve the purpose of lowering postprandial blood glucose. Therefore, glycosidase inhibitors need to be chewed at the same time as the first meal to increase the contact area between food and drugs, so as to give full play to the hypoglycemic effect of drugs. 4, insulin sensitizers, DPP-4 inhibitors, sodium-glucose cotransport protein 2 inhibitors, etc., drugs with different mechanisms of action are recommended to be taken before meals, in order to facilitate the absorption and action of drugs.