How long it takes to take metformin to take effect needs to vary according to body type, metformin is a hypoglycemic drug, according to pharmacokinetics, after oral metformin, the blood concentration reaches the peak in about 2.5 hours, and the time to reach a stable blood concentration is 24~48 hours, therefore, generally 2.5~48 hours can play a role in the effect. Metformin is an oral hypoglycemic agent, is the main drug for type 2 diabetic patients to control hyperglycemia, how long to take metformin to play the effect of lowering glucose, and personal constitution, for most patients, according to the pharmacokinetics, after oral metformin, blood concentration reaches the peak in about 2.5 hours, and the time to reach a stable blood concentration is 24~48 hours. Common adverse reactions to metformin are nausea, vomiting, diarrhea, abdominal pain, and loss of appetite. It should be noted that it is contraindicated in severe renal failure, ketoacidosis, decompensated heart failure, severe infections and trauma, acute alcoholism, and hypersensitivity to metformin ingredients. In addition to metformin, sulfonylureas such as glibenclamide, non-sulfonylureas such as repaglinide, nateglinide and other drugs, the use of which should be under the guidance of a doctor, as well as attention to diet and balanced meals.