As the blood sugar level fluctuates 24 hours, fasting and postprandial blood sugar reflect only the instantaneous blood sugar level at a specific time, and are easily affected by factors such as eating, exertion and stress, which is very unfavorable to the treatment and diagnosis of the disease. According to the survey, only less than 30% of type 2 diabetic patients in China have their blood glucose attained, and the changes of blood glucose should be monitored by testing glycated hemoglobin. Because compared to fasting and postprandial blood glucose, glycated hemoglobin is a more stable and reliable reflection of the patient’s blood glucose level for about 90 days, and is the internationally recognized “gold standard” for diabetes monitoring. For this reason, it is advisable for diabetic patients to have their glycosylated hemoglobin tested every 3 months to 6 months. Glycosylated hemoglobin is the product of the combination of hemoglobin and blood sugar in the red blood cells of the blood. The higher the glycosylated hemoglobin, the more blood sugar is combined with hemoglobin, and the more severe the disease. Therefore, glycosylated hemoglobin has become an important indicator to understand whether diabetes is well controlled or not. Overseas, glycosylated hemoglobin monitoring has been used as the gold standard for determining the efficacy of diabetes and adjusting treatment. The effect of increased glycosylated hemoglobin on the human body is multifaceted, it can change the affinity of red blood cells for oxygen, causing tissue and cellular hypoxia, accelerating the formation of cardiovascular and cerebrovascular complications; if the crystals in the eyes are glycated, it can lead to cataracts; glycosylated hemoglobin can cause thickening of the glomerular basement membrane and induce diabetic nephropathy; elevated glycosylated hemoglobin can also cause an increase in blood lipids and blood viscosity, which is an important factor in the occurrence of cardiovascular and cerebrovascular diseases. It is an important factor for the occurrence of cardiovascular and cerebrovascular diseases. It is found that glycosylated hemoglobin and blood glucose concentration are obviously positively correlated, and every 1% increase in glycosylated hemoglobin increases the average level of blood glucose by about 1.5 mmol/L in the first 1 to 3 months. However, for diabetic patients with large fluctuations in blood glucose, the instantaneous blood glucose measurement of only one or two times does not give a full picture of the disease over a period of time, which makes it difficult to formulate a reasonable treatment plan. Glycosylated hemoglobin measurement makes up for this deficiency, and is therefore known as the “gold standard” for monitoring diabetes mellitus. The normal value of glycosylated hemoglobin is 4.4% to 6.2%, and if it is greater than 7%, it is prone to chronic complications. In addition, glycosylated hemoglobin can be reduced when suffering from various anemia, bleeding disorders or applying drugs such as benzoin, morphine, dihydrocodone, etc., and can be increased when taking a large amount of aspirin, vitamin C or renal insufficiency. In addition to determining the glycemic control, glycosylated hemoglobin also has significance for the determination of the following conditions. 1. Identification of patients in coma: In cerebrovascular emergencies, blood glucose may increase due to stress reaction, but glycated hemoglobin is normal. If glycosylated hemoglobin is increased, it indicates that the patient has hyperglycemic state. 2. Patients with high glycosylated hemoglobin should be alert to the occurrence of ketoacidosis. 3, gestational diabetes is not enough to measure blood glucose, must monitor glycosylated hemoglobin, and keep it below 8%. This can avoid the occurrence of huge fetuses, stillbirths and malformed fetuses. 4.Guiding treatment: If the glycosylated hemoglobin of a patient has been measured, the average blood glucose level can be projected, and then the projected value can be compared with the fasting blood glucose value of the same specimen, which can predict the recent good or bad blood glucose control.