The diagnosis of diabetes mellitus is mainly based on the levels of venous blood at different time points, the specific criteria are: random blood glucose ≥11.1mmol/L; fasting blood glucose ≥7.0mmol/L; OGTT (oral glucose tolerance test) 2-hour blood glucose ≥11.1mmol/L; HbA1c (glycated hemoglobin) ≥6.5%. Diabetes mellitus can be diagnosed if there are typical clinical manifestations of diabetes, such as “three more and one less” symptoms of excessive drinking, excessive eating, excessive urination, and fatigue and emaciation, together with one of the above four symptoms. However, it should be noted that those who do not have the typical symptoms of diabetes need to be re-examined on another day for the diagnosis to be established. For those who do not meet the above diagnostic criteria but have abnormal blood glucose values, the criteria are as follows: 6.1mmol/L≤fasting blood glucose＜7.0mmol/L and 2-hour blood glucose＜7.8mmol/L after sugar loading are impaired fasting blood glucose; fasting blood glucose＜7.0mmol/L and 7.8mmol/L≤2-hour blood glucose after sugar loading are＜11.1mmol/L, and glucose tolerance is impaired. Hypoglycemic state. If you feel unwell, consult a doctor promptly.