Generally, 5 hours after meal belongs to fasting state, when the stomach has basically emptied. If the patient has no eating behavior, it is fasting blood glucose, and the value of 3.9-6.1mmol/L is normal, more than 7.0mmol/L indicates the possible existence of diabetes. If the patient has eating behavior in the middle, the blood sugar 5 hours after meal can be considered as random blood sugar. Random blood glucose generally refers to the blood glucose at any time after eating a meal. Random blood glucose should not exceed 11.1 mmol/L. If it exceeds 11.1 mmol/L, there is a possibility of diabetes mellitus. During the diagnosis of diabetes, the 5-hour postprandial blood glucose usage rate is lower, and fasting blood glucose and 2-hour postprandial blood glucose are used as the standard. If a patient has a higher than normal fasting blood glucose or 2-hour postprandial blood glucose, but does not meet the diagnostic criteria for diabetes, a glucose tolerance test can be done. The glucose tolerance test is generally done by dissolving 75g of glucose in 200ml of liquid, and the patient drinks it in 5 minutes in fasting state. Starting from the first sip of sugar water, the concentration of blood glucose is tested in half hour, one hour, two hours and three hours, and these blood glucose values are converged into a curve and then compared with the normal values. If abnormalities occur, the glucose tolerance is reduced or diabetes occurs. The blood glucose 5 hours after meal is basically calculated as the value of fasting blood glucose due to gastric emptying, and the easy way is to observe whether it exceeds the value of random blood glucose. If the diagnosis standard of diabetes is met, diet, exercise and medication should be carried out according to the diabetes standard to keep the blood sugar under relatively stable control.