Diabetic patients with glycosylated hemoglobin > 7% are prone to combined complications, and glycosylated hemoglobin values above 9% indicate poor glycemic control, but the specific life expectancy of patients cannot be generalized. Diabetic patients are classified into 4 levels according to their blood sugar control, which are satisfactory, good, fair and poor. When glycosylated hemoglobin >8%, it means that blood sugar control is poor, and serious cases may even lead to ketoacidosis, causing coma, which can endanger patients’ lives in a short time. Moreover, diabetic patients with poor glycemic control are prone to cardiovascular diseases, such as cerebral infarction and heart attack, which can lead to a decrease in quality of life in the mild cases and death in a short time in the severe cases. In addition, if patients are actively treated to bring their blood glucose back to standard, they may not have complications in a short time, or the complications will not progress anymore, and those with ideal control will not even affect their life expectancy. In conclusion, diabetic patients should be treated aggressively and follow the five carriage principle to effectively control blood glucose and improve their prognosis.