High glycosylated hemoglobin does not necessarily mean diabetes, if the glycosylated hemoglobin ≥ 6.5% and at the same time there are “three more and one less” clinical symptoms can be diagnosed as diabetes, but also need to be combined with fasting blood glucose, postprandial glucose and other tests to determine the synthesis. Glycated hemoglobin is formed by combining hemoglobin and glucose in red blood cells, and its value can reflect the average level of blood glucose in the past 8 to 12 weeks. Combined with fasting blood glucose, postprandial blood glucose and other indexes, it can better assess the patient’s blood glucose situation or treatment effect. Diabetes is diagnosed when fasting blood glucose ≥7.0mmol/L, or two-hour postprandial blood glucose ≥11.1mmol/L, or random blood glucose ≥11.1mmol/L, or glycated hemoglobin ≥6.5%, and when any of the above criteria is met and there are clinical signs of “three more and one less” at the same time. “Three more and one less” means polyuria, polydipsia, polyphagia and weight loss. When the patient’s glycosylated hemoglobin is high, it is recommended to consult a doctor in time to improve the relevant examination.