Glycated hemoglobin 5.9% is within the normal range and cannot be diagnosed as diabetes mellitus, which needs to be clearly diagnosed in combination with fasting blood glucose, postprandial blood glucose and other indicators. Glycated hemoglobin is an indicator that reflects the average blood glucose in the past 2-3 months, and the normal range is 4.0%-6.0%, so 5.9% of glycated hemoglobin is within the normal range. With typical symptoms of diabetes, such as polydipsia, polyphagia, polyuria, weight loss, etc., and meet the glycated hemoglobin ≥ 6.5%, or fasting blood glucose ≥ 7.0 mmol/L, or two hours after meal blood glucose ≥ 11.1 mmol/L, or random blood glucose ≥ 11.1 mmol/L, can be diagnosed with diabetes mellitus, so the glycated hemoglobin of 5.9% is not consistent with the diagnosis of diabetes mellitus. However, glycated hemoglobin 5.9% can not completely exclude the possibility of diabetes, if there is excessive drinking, excessive food, excessive urination, weight loss, etc., you should consult a doctor in time to improve the examination of fasting blood glucose, postprandial blood glucose, glucose tolerance test, and so on. Glycated hemoglobin 5.9% cannot be diagnosed as diabetes mellitus, and it is recommended to be evaluated by a medical professional in conjunction with other tests.