The 30-minute postprandial blood glucose is a random blood glucose. Under normal circumstances, random blood glucose <11.1mmol/L is considered normal. Normally, if the 30-minute blood glucose value is more than 11.1 mmol/L, there is a risk of diabetes, and fasting blood glucose and 2-hour postprandial blood glucose should be measured as soon as possible. The World Health Organization's Expert Committee on Diabetes mellitus established in 1980 that the diagnosis of diabetes mellitus is based on fasting blood glucose, 2-hour postprandial blood glucose, and random blood glucose testing. Diabetes may occur when any of the fasting blood glucose > 7.0 mmol/L, 2-hour postprandial blood glucose > 7.8 mmol/L, and random blood glucose > 11.1 mmol/L are met. Therefore, the maximum blood glucose of 30 minutes after meal should not exceed 11.1mmol/L. Otherwise, the patient’s diet should be controlled according to the control standard of diabetes mellitus, and the total amount of food intake per day should be controlled in general, meanwhile, a certain amount of exercise should be increased. After diet and exercise, fasting blood glucose and 2-hour postprandial blood glucose are tested. If they are still not up to standard, consider whether diabetes has occurred.