Fasting blood sugar 5.5mmol/L is generally not dangerous. Generally, the blood glucose value measured after 8~10 hours of fasting is called fasting blood glucose, the normal range of fasting blood glucose value is 3.9~6.1mmol/L, and the normal 2 hours blood glucose after meal is not more than 7.8mmol/L. At present, the fasting blood glucose 5.5mmol/L belongs to the normal range. When fasting blood glucose is greater than or equal to 6.1mmol/L but less than 7.0mmol/L and 2 hours after glycemic load blood glucose is less than 7.8mmol/L, it suggests that the fasting blood glucose is impaired, at this time, should consult a doctor in a timely manner, under the guidance of the doctor to give the dietary and exercise control, to achieve a reasonable dietary control, appropriate exercise, weight loss, in order to reduce the probability of diabetes. Patients who are found to have abnormal blood glucose levels should seek prompt medical attention.