Postprandial blood glucose over 20mmol/L proves that diabetes is more serious, and normal postprandial blood glucose will not exceed 11.1mol/L. Therefore, when blood glucose reaches 20mmol/L, it is more serious, mainly seen in insufficient insulin secretion and some stress states. 1. Insufficient insulin secretion: For people who have not suffered from diabetes before, if you find that postprandial blood glucose reaches 20mmol/L, consider It is possible that insufficient insulin secretion has led to diabetes. It is usually accompanied by the performance of polyphagia, polyphagia, polyuria and lethargy, and it is easy to have very high blood glucose because it is not easy to be detected or detected late. 2. Stress state: If a patient with diabetes mellitus has poor blood glucose control and has a postprandial blood glucose greater than 20mmol/L, it is important to pay attention to whether the patient has some stress state, including whether there is myocardial infarction, cerebral hemorrhage, cerebral thrombosis, diabetic foot, lung infection, urinary tract infection, or any trauma, as well as whether there are serious mood swings, etc., which cause excessive secretion of glucagon into the blood within a short period of time. If the postprandial blood sugar is greater than 20 mmol/L, it is a more critical situation. You should immediately go to the hospital for examination to clarify the cause, active treatment, and check urine ketone bodies to see if ketosis has occurred.