Postprandial blood glucose generally refers to two hours after the meal blood glucose, fasting blood glucose and high postprandial blood glucose are both harmful to the body, there is no which high is more terrible. The normal value of fasting blood glucose is 3.9~6.1mmol/L. The fasting state means no calorie intake for at least 8 hours, which can reflect the basic secretion function of pancreatic B cells. Postprandial blood glucose refers to the blood glucose value measured two hours from the first bite of food, the normal value should be <7.8mmol/L, reflecting the reserve function of pancreatic islet B cells. Whether fasting blood glucose or high postprandial blood glucose, will be harmful to the organism, may appear diabetes acute complications, such as diabetic ketoacidosis, hyperosmolar hyperglycemic syndrome, etc., but also may appear diabetic chronic complications, such as diabetic nephropathy, diabetic retinopathy, diabetic neuropathy. In summary, elevated fasting blood glucose or postprandial blood glucose will produce damage to the organism, so it is particularly important to control blood glucose, and it is recommended that treatment be carried out under the guidance of a professional doctor.