Diabetes cannot be diagnosed solely on the basis of a high glycosylated hemoglobin. The normal value of glycosylated hemoglobin is 4-6%, and 6.9% is already higher than the normal range, which suggests that there may be blood sugar abnormalities. Glycated hemoglobin ≥6.5% as one of the diagnostic criteria for diabetes should also be combined with typical clinical symptoms (excessive drinking, excessive eating, excessive urination, weight loss) or reviewed on another day. In addition, fasting blood glucose or random blood glucose or glucose tolerance test can also assist in the diagnosis of diabetes mellitus. Diabetes mellitus can be diagnosed by the presence of typical symptoms of diabetes mellitus and a random blood glucose ≥11.1 mmol/L or a fasting blood glucose ≥7.0 mmol/L or glucose tolerance test with a 2-hour blood glucose ≥11.1 mmol/L. In the presence of elevated glycosylated hemoglobin, it is recommended to seek medical attention to complete the relevant examinations, clarify the condition and treat it as soon as possible in order to reap the best prognosis.