Metformin is a very good glucose-lowering drug and has the effect of weight reduction. Metformin is the first-line drug for the treatment of type 2 diabetes, both domestically and internationally, and can be combined with other drugs to lower glucose in cases where treatment with metformin alone is not effective. Metformin mainly reduces the output of liver sugar and increases the synthesis of liver glycogen by increasing the utilization of glucose in peripheral tissues. Metformin also has the effect of improving insulin resistance, which means it can reduce body weight. Therefore, metformin is ideal for obese patients with diabetes to both lower sugar and lose weight.