You cannot eat grapes with high blood sugar because they are a high-calorie fruit that contains more sugar, which produces more heat and affects the blood sugar of diabetics. Diabetic patients should first bring down their blood sugar before they can eat grapes. Diabetic patients should control their fasting blood sugar below 6.0mmol/L and two hours after meal blood sugar below 8.0mmol/L. In this case blood sugar reaches the ideal, that is, fasting blood sugar at 6.0mmol/L and two hours after meal blood sugar below 8.0mmol/L, they can eat grapes in small amounts. They should be eaten between meals, no more than twice a day, and preferably no more than 70 grams each time. Patients should also monitor their blood sugar frequently while eating grapes. After eating 70 grams of grapes, it does not affect the change of blood sugar, and this situation can continue to eat grapes.