Patients who want to know if they have diabetes can simply draw venous blood and check fasting plasma glucose and glycosylated hemoglobin. If the fasting glucose is below 6.1mmol/L and the glycated hemoglobin is below 6.5%, you can basically tell that the patient has normal blood sugar and is not diabetic. A more accurate method is to do an oral glucose tolerance test (OGTT) with 75g of glucose and draw venous blood to check plasma glucose. If the fasting glucose is below 6.1mmol/L and the OGTT 2-hour glucose is below 7.8mmol/L, the glucose is considered normal. If fasting blood glucose is greater than or equal to 7.0mmol/L or OGTT2 hour blood glucose is greater than or equal to 11.1mmol/L, the patient should also be diagnosed with diabetes according to whether he/she has typical symptoms of diabetes, i.e., drinking more, urinating more, eating more, and losing weight, if these symptoms are present. If there are no typical symptoms of diabetes, it is necessary to recheck fasting blood sugar or OGTT2 hour blood sugar on another day, and if it still reaches one of the above two criteria, it can be diagnosed as diabetes.