Glycosylated hemoglobin is 6.6% and the average blood glucose is about 7.9 mmol/L. This value is only an estimate and does not reflect the immediate blood glucose level. Glycated hemoglobin measurement reflects the average blood glucose level in the 2 to 3 months prior to the measurement, whereas blood glucose measurement reflects the blood glucose level at this moment. Normal glycosylated hemoglobin ranges from 4.0% to 6.0%, and diabetic patients generally need to be controlled below 7.0%. Diabetes mellitus can be diagnosed when the glycosylated hemoglobin is 6.6% and there are clinical signs of “three more and one less”. It is recommended to improve the indicators of fasting blood glucose, postprandial blood glucose, etc., which can better assess the patient’s blood glucose situation or the effect of treatment. Glycosylated hemoglobin 6.6% is recommended to seek prompt medical attention.