Metformin should be taken in small doses, gradually increasing the dose with meals. It is recommended to take the medication under the guidance of a doctor, during which regular reviews are conducted. Metformin is the first-line drug for the treatment of type 2 diabetes mellitus, with obvious glucose-lowering effect, preferred for type 2 diabetes mellitus in which simple dietary control and physical exercise are ineffective in controlling blood glucose, and can be used for single-drug treatment, or can be combined with sulfonylureas or insulin. In order to reduce the occurrence of gastrointestinal complications, and also in order to use the smallest dose of the drug to make the patient’s blood glucose enough to control, should be taken from a small dose, gradually increase the dose, and monitor blood glucose regularly during the use of the drug. Common adverse reactions to metformin include gastrointestinal reactions, skin irritation, and lactic acidosis, and it is contraindicated in patients with severe complications, alcoholism, and severe renal insufficiency. Metformin should be taken under medical supervision.