Postprandial blood glucose of 2.4mmol/L belongs to postprandial hypoglycemia, which can be caused by type 2 diabetes mellitus, dumping syndrome, reactive hypoglycemia, insulinoma and other factors. 1. Type 2 diabetic hypoglycemia: Postprandial hypoglycemia can be caused by the irrational use of hypoglycemic drugs or excessive dosage, and at the same time, low intake of food. 2. Dumping syndrome: after major gastrectomy, the stomach empties too fast and blood sugar will rise rapidly stimulating the pancreas leading to excessive insulin secretion by the pancreas, causing blood sugar to drop. 3. Reactive hypoglycemia: it is caused by the delay of the peak of insulin secretion, which usually occurs 2~4 hours after meal. 4. Insulinoma: It is hypoglycemia caused by excessive insulin secretion due to pancreatic islet B-cell tumor or B-cell hyperplasia. When postprandial blood glucose of 2.4mmol/L occurs, it is necessary to replenish sugary food immediately, and it is recommended to go to the hospital and ask the doctor to make a judgment and clarify the cause of the disease.