High fasting blood sugar, you can take metformin extended-release tablets before bedtime, but please take it under the guidance of a doctor. Metformin extended-release tablets belong to the biguanide class of hypoglycemic drugs, can reduce hepatic glucose production, inhibit intestinal absorption of glucose, and then achieve the purpose of lowering blood sugar, can be used for the treatment of purely rely on dietary control, physical exercise can not be very good control of blood glucose in patients with type 2 diabetes mellitus; allergy to the drug, severe renal failure, trauma, serious infections and other patients are prohibited. The efficacy of this drug can be maintained for about 24 hours after administration, so for patients with elevated fasting blood glucose, metformin extended-release tablets can be taken before bedtime to help control the fasting blood glucose concentration on the following day. Adverse reactions such as nausea, vomiting, abdominal pain, loss of appetite, palpitations, hot flashes, hypoglycemia, myalgia, headache, dizziness, rash, and urticaria may occur after taking the drug. Patients who need to use Metformin for treatment are advised to use the drug under the guidance of a doctor and should not use the drug blindly on their own.