The standard value of glycosylated hemoglobin test is 4%~6%. Due to different testing methods and reagents, the reference indexes are different in each hospital and need to be analyzed specifically. Glycated hemoglobin is produced by combining hemoglobin in red blood cells with glucose through a non-enzymatic reaction. Because of the slow and irreversible situation, it can reflect the average level of blood glucose control within 8~12 weeks. Its structure is relatively stable, so it can be used as the main indicator of diabetes diagnosis and control. The China Type 2 Diabetes 2020 Prevention and Control Guidelines include glycosylated hemoglobin in the diagnostic criteria, which can be used as an additional diagnostic criterion for diabetes mellitus, but diabetes mellitus cannot be ruled out with less than 6.5%, and needs to be judged according to the fasting blood glucose level, the 2-hour postprandial glucose level, and the random blood glucose level. Studies have shown that for every 1% reduction in glycated hemoglobin in diabetic patients, the risk of death associated with diabetes is significantly reduced, and the risk of cardiovascular disease morbidity is significantly reduced. When testing glycated hemoglobin, it is recommended to consult the endocrinology department of a regular hospital.