Eating watermelon may affect blood sugar. Watermelon contains a certain amount of sugar, and the glycemic index of watermelon is not low among fruits, which is 72, belonging to the high glycemic index food, so eating watermelon will affect blood sugar, especially after eating a large amount of watermelon at one time may cause large fluctuations in blood sugar. At the same time, watermelon contains vitamin B, vitamin A, vitamin C, carotene, calcium, potassium, phosphorus and other nutrients, blood glucose control of stable diabetic patients can eat a small amount of watermelon, to be able to supplement nutrients. Patients with hyperglycemia should cooperate with their doctors and maintain a healthy diet in their daily life, whether they have hyperglycemia or are healthy, to help maintain stable blood sugar.