There is no such thing as an efficacious drug for diabetes mellitus, and suitable hypoglycemic drugs should be chosen according to the condition. Common oral hypoglycemic drugs include metformin, thiazolidinediones, α-glucosidase inhibitors, insulinotropic secretagogues and other drugs, each of which has its own indications and contraindications. 1. Metformin: Metformin is the most commonly used. it is the first-line drug for patients with type 2 diabetes mellitus. it cannot be used in patients with severe hepatic or renal insufficiency, diabetic ketoacidosis, or alcoholism, and its adverse effects include lactic acidosis. 2. Thiazolidinediones: representative drugs are rosiglitazone and pioglitazone. Applicable to obesity, insulin resistance obvious type 2 diabetes. Severe hepatic and renal insufficiency, heart failure patients are prohibited, adverse reactions are weight gain and edema. 3. α-glucosidase inhibitors: commonly used drugs include acarbose and voglibose. It is suitable for those who eat mainly carbohydrates, whose fasting blood glucose is not too high and postprandial blood glucose is obviously elevated. It is not suitable for those who have gastrointestinal dysfunction, and the common adverse reaction is gastrointestinal reaction, such as abdominal distension. 4. insulinotropic secretagogues: including sulfonylureas and glinides, sulfonylureas for type 2 diabetes mellitus non-obese patients; glinides for patients with high postprandial glucose. 1 diabetes mellitus patients, diabetic ketoacidosis, severe burns, allergies are prohibited, the common adverse reactions are hypoglycemia, hepatic function impairment. There are many other types of hypoglycemic drugs, which also include DPP4 inhibitors, SGLT2 inhibitors, such as selegiline, dagliflozin and so on. Diabetic patients should choose the appropriate medication under the guidance of their doctors.