Metformin reduces body weight by increasing insulin sensitivity and lowering insulin levels in the body, and in a way, it can have the therapeutic effect of preventing and delaying the onset of diabetes. In obese patients, oral metformin can increase insulin sensitivity and lower insulin levels, while suppressing the patient’s appetite and reducing calorie intake, thus reducing body weight, which can prevent the onset of diabetes. Patients with abnormal glucose tolerance, including some people whose blood glucose is higher than normal, but who do not meet the diagnostic criteria for diabetes, can take oral metformin to suppress appetite, increase insulin sensitivity, reduce body weight, and delay the onset of diabetes. Of course, the best way to prevent type 2 diabetes is to control diet and exercise, and to control weight fundamentally to prevent and control the onset of diabetes.