A prolonged fasting blood glucose of about 8mmol/L has reached the diagnostic criteria for diabetes mellitus. Prolonged fasting hyperglycemia may lead to the development of diabetic complications such as diabetic microangiopathy, diabetic macrovascular lesion, diabetic peripheral neuropathy, etc. Normal fasting blood glucose in adults is 3.9~6.1mmol/L. Diabetes mellitus should be considered when the fasting blood glucose is greater than 7.0mmol/L for several times. Diabetes mellitus patients who are in a long-term hyperglycemic state without timely intervention and treatment will lead to damage to various tissues and organs, and the development of chronic complications of diabetes mellitus such as diabetic microangiopathy, diabetic macrovascular lesions, diabetic peripheral neuropathy, diabetic foot and so on. Fasting blood glucose for a long time around 8mmol / L may also lead to a decline in the body’s immunity, which can easily lead to aggravation of infections, wounds are not easy to heal and so on. Therefore, it is recommended that patients with fasting blood glucose of 8mmol/L should go to a regular hospital in time. Under the guidance of specialists to assess the condition and determine the treatment plan. Only by controlling blood glucose within a good range can the further development of the disease be effectively prevented.