Clinically, diabetic patients can take oral metformin to control their blood sugar. Metformin is the first-line drug for type 2 diabetes, which can better reduce glycated hemoglobin by inhibiting the output of liver glycogen and promoting the utilization of glucose in peripheral tissues while controlling fasting blood sugar and 2 hours postprandial blood sugar of patients. Metformin can also reduce body weight, regulate blood lipids and anti-atherosclerosis, so metformin is preferred for type 2 diabetic patients, and if the gastrointestinal tract can tolerate and is not accompanied by renal impairment, it is recommended to apply metformin throughout the treatment. For type 1 diabetic patients with large blood glucose fluctuations, metformin therapy can also be used to assist in making blood glucose control stable.