A blood sugar of 22.9mmol/L is dangerous and requires prompt treatment. The normal range of fasting blood glucose is 3.9-6.1mmol/L, and the normal postprandial blood glucose should be less than 7.8mmol/L. Whether it is fasting blood glucose or postprandial blood glucose 22.9mmol/L, it is a high number, and it is recommended to go to the emergency department in time to deal with the problem, because acute complications of diabetes, such as diabetic ketoacidosis and hyperosmolar hyperglycemia syndrome, can be serious and life-threatening, may occur. It is recommended that patients find blood glucose 22.9mmol/L go to a regular hospital in time to be examined and treated under the guidance of a doctor.