Glycosylated hemoglobin is a product of non-enzymatic glycosylation of glucose in the blood, with hemoglobin in the red blood cells. The life span of red blood cells is 120 days, so glycated hemoglobin is an indicator of the average blood glucose level over the past 2-3 months. The price of glycosylated hemoglobin measurement is around$75, which varies slightly by hospital level and by test method. The main applications of glycosylated hemoglobin are as follows: i. To assist in the diagnosis of diabetes mellitus. The diagnosis of diabetes is based on fasting and two-hour postprandial blood glucose. When glycosylated hemoglobin > 6.5%, it can also be diagnosed as diabetes. Second, glycosylated hemoglobin is used to judge the blood sugar control and make up for the inadequacy of fasting and postprandial blood sugar values representing instantaneous blood sugar. Third, glycated hemoglobin can be used to identify stress hyperglycemia, and diabetes-induced hyperglycemia, especially in patients with severe stress.