A 2-hour postprandial blood glucose, tested after drinking water in between, is usually accurate. The 2-hour postprandial blood glucose is the blood glucose measured 2 hours after the first bite of food. You can drink water during the 2-hour postprandial blood glucose test. Drinking a moderate amount of water generally does not have a significant effect on the 2-hour postprandial blood glucose, but note that you should choose non-calorie purified water, mineral water, etc., and avoid drinking a lot of sugary drinks. It is generally required that normal people’s 2-hour postprandial blood glucose is less than 7.8mmol/L, and diabetic patients’ 2-hour postprandial blood glucose needs to be controlled below 10mmol/L. In order to accurately determine the blood glucose level, in addition to testing the 2-hour postprandial blood glucose, fasting blood glucose and glycated hemoglobin should also be tested for a comprehensive assessment. When high or low blood sugar is detected, timely medical attention is required and treatment should be carried out under the guidance of specialized physicians.