Three hours after meal is generally belong to the random blood sugar. Random blood glucose refers to the amount of glucose in the blood measured at any time except the fasting state, so the three hours after the meal belongs to random blood glucose, and its normal range is generally 3.9~11.1mmol/L. If the random blood glucose is ≥11.1mmol/L, then it is necessary to suspect diabetes mellitus. If the random blood glucose ≥ 11.1mmol / L need to be suspected of diabetes, if necessary, but also need to improve the glucose tolerance test and fasting blood glucose test and combined with the patient with or without polydrinking, polyphagia, polyuria, weight loss and other diabetes-related symptoms to make a comprehensive judgment. Patients who need blood glucose testing should actively cooperate with the doctor, and if abnormal blood glucose occurs, please go to the hospital immediately.