The best way to take metformin is usually with or after meals, starting with a small dose and gradually increasing the dose, regular monitoring of blood glucose to adjust the dosage, and if necessary, can be used in combination with drugs such as sulfonylureas or insulin. Metformin belongs to the class of biguanide glucose-lowering drugs, can inhibit hepatic glucose output, increase the utilization of glucose in peripheral tissues, is currently the first-line drugs for the treatment of type 2 diabetes mellitus. It is recommended that metformin be taken with meals, or after meals, fasting has a certain degree of gastrointestinal tract irritation; in addition, starting with a small dose, slowly increasing the dose can improve gastrointestinal tract tolerance. Common adverse reactions to metformin include gastrointestinal reactions, skin irritation and lactic acidosis, and it is contraindicated in patients with serious complications, pregnant women, lactation, alcoholism, and severe renal insufficiency. Metformin needs to be taken under the supervision of a doctor and should not be used without authorization.