Postprandial blood glucose 18mmol/L, the dose of insulin needs to be decided according to the insulin dosage form and the physical condition of the diabetic patient, there is no fixed dosage, which can be carried out under the guidance of the doctor. There are many types of insulin, including short-acting insulin, intermediate-acting insulin and long-acting insulin. Because of the different insulin dosage forms, the time for insulin to work is also different. Diabetic patients with postprandial blood glucose of 18mmol/L can choose the injection dose according to the action time of insulin, which can be further consulted under the guidance of doctors. In addition, postprandial blood glucose 18mmol / L diabetic patients, the dose of insulin injection also need to be decided according to the physical condition of diabetic patients. It should be noted that insulin is contraindicated for those who are allergic to insulin, and the risk of hypoglycemia may occur with the application of insulin, so blood glucose should be closely monitored. If diabetes is diagnosed, early and standardized treatment is recommended to minimize the adverse effects of the disease.