With the gradual understanding of diabetes knowledge, most people have realized the importance of fasting and 2-hour postprandial blood glucose monitoring, and often take the measured value of both as the standard of blood glucose control. In fact, fasting and 2-hour postprandial blood glucose are the standards for diagnosing diabetes, while the standard for measuring the level of diabetes control is glycated hemoglobin. Fasting blood glucose and postprandial blood glucose only reflect the blood glucose level at that specific time when blood is drawn, and are easily affected by factors related to eating and sugar metabolism. Glycosylated hemoglobin, on the other hand, can reflect the average blood glucose level in the 120 days before the test in a stable and reliable manner, and is not much affected by the time of blood draw, whether fasting or not, whether insulin is used or not, etc. Glycosylated hemoglobin (English code HbA1c) is a product of hemoglobin binding to blood glucose in the red blood cells of human blood, which is an irreversible reaction and is proportional to blood glucose concentration, and remains for about 120 days. In patients treated for diabetes, it is not affected by an occasional increase or decrease in blood glucose, and usually reflects the average level of blood glucose control in the last 8-12 weeks, thus becoming the new standard for diabetes diagnosis and the “gold standard” for treatment monitoring. If fasting blood sugar or postprandial blood sugar is not well controlled, glycated hemoglobin is unlikely to meet the standard. The world authorities have clear control indexes for glycated hemoglobin, ADA (American Diabetes Association) recommends that glycated hemoglobin be controlled at less than 7%, IDF (International Diabetes Federation) recommends that glycated hemoglobin control standard is ≤6.5%, and China sets the glycated hemoglobin control standard for diabetic patients at less than 6.5%. Some diabetic patients see that their fasting blood sugar and postprandial blood sugar are relatively normal, so they are reluctant to test their glycosylated hemoglobin. Therefore, it is very important to monitor glycated hemoglobin regularly. Based on the results of the glycosylated hemoglobin test, the doctor can determine whether the patient’s health care plan is effective, whether he is eating properly, whether he is exercising properly, whether his blood sugar is well controlled, and whether he needs to adjust his treatment plan. Therefore, it is especially important to popularize the knowledge of diabetes, update the concept of treatment, monitor and keep the glycosylated hemoglobin up to the target, and carry out the comprehensive treatment measures led by diet therapy earlier and more reasonably to control the development of diabetes complications. Glycosylated hemoglobin should be checked every 3 months in diabetic patients whose blood glucose control has not reached the target or after the adjustment of treatment plan. Glycosylated hemoglobin should also be checked at least twice a year after blood glucose control has reached the target.