Metformin is an oral hypoglycemic agent often taken by diabetic patients. The mechanism of action of metformin is to promote peripheral glucose utilization and anaerobic enzymes, which can improve insulin resistance and enhance insulin sensitivity, and metformin can control appetite, which is good for obese patients to control their weight, so diabetic patients will experience weight loss after taking metformin. If diabetic patients are getting thinner after taking metformin, they should do the following: First, check the blood glucose control to exclude weight loss caused by high blood glucose, because when diabetic patients have significantly higher blood glucose, they will also appear to be getting thinner in weight. Second, adjust the diet and exercise program to avoid patients with too strict dietary control or too much exercise, resulting in weight loss significantly, you can appropriately increase the total caloric intake. Third, if necessary, you can stop using metformin and switch to other oral hypoglycemic drugs, or even insulin to control blood sugar. Fourth, be alert to other diseases that may also cause wasting, such as hyperthyroidism, malignant tumors and other diseases.