The difference between acarbose and metformin is usually reflected in the mechanism of action, indications, adverse reactions and so on. 1. Mechanism of action: Acarbose is an α-glucosidase inhibitor, which inhibits the α-glucosidase of the small intestine mucosa, delays the absorption of sugar, and thus reduces blood glucose; metformin is a biguanide hypoglycemic drug, which inhibits the output of hepatic glucose, improves the peripheral tissues’ sensitivity to insulin, and increases the glucose uptake and utilization of peripheral tissues, and then reduces blood glucose. 2. Indications: Acarbose and metformin can be used in obese patients with type 2 diabetes mellitus, but the former for postprandial hyperglycemia to take the effect is more significant. 3. Adverse reactions: Acarbose and metformin can cause gastrointestinal reactions such as nausea, vomiting, etc., but the latter can also be manifested as lactic acidosis and other adverse reactions. If there is a need to take the above two drugs, it is recommended to choose under the guidance of a professional doctor in a regular hospital to avoid unauthorized use of drugs.