Clinically, patients drinking water after eating, especially drinking plain water, has little effect on postprandial blood sugar. Plain water is a non-caloric beverage, which has little effect on blood sugar. Diabetic patients are recommended to drink more plain water, which can increase blood volume and excrete through urine, which can assist the excretion of urine sugar and facilitate the control of blood sugar. The influence of postprandial blood sugar of patients depends mainly on the amount of carbohydrates and fatty foods eaten by patients. If the amount of carbohydrates consumed is too much, especially those with high glycemic index, such as rice porridge, etc., it can cause a rapid spike of blood sugar after meals. Patients who eat too much food high in fats and oils can cause a postprandial spike in blood sugar and have a more lasting effect on blood sugar. Therefore, diabetic patients should control sweets and fried foods in their diet, while the amount of carbohydrates should not be too much, otherwise it will cause the postprandial blood glucose to rise.