The latest normal standard of glycated hemoglobin is 4%~6%. Due to the different examination methods and reagents, the reference indexes of each hospital may be different and need to be analyzed specifically. Glycated hemoglobin reflects the average level of blood glucose of diabetic patients in the last 2~3 months. Random blood glucose reflects the blood glucose level at a certain point, which can be too high due to stress and overfeeding, and can be low due to underfeeding. Glycated hemoglobin formation is irreversible and correlates with blood glucose concentrations during that period. Glycated hemoglobin should be controlled to <7.0% in adults; <6.5% in young patients with a short course of disease, no complications or comorbidities, and a low risk of hypoglycemia; and <8.0% in patients with a longer course of disease, a history of cardiovascular disease, or a very high risk of cardiovascular disease. Patients with diabetes mellitus should have their glycosylated hemoglobin checked regularly to understand the level of blood glucose control, and usually take hypoglycemic drugs as prescribed by the doctor to control their blood glucose. When uncomfortable symptoms occur, consult a doctor in time.