Both normal people and diabetic patients can have elevated blood sugar after consuming watermelon. Watermelon has a high sugar content and a high glycemic index. The glycemic index of watermelon is 72, which can lead to elevated blood sugar in both normal people and diabetic patients. Normal people consume watermelon cause blood sugar rise, but due to the normal function of the body’s pancreatic islets, can secrete a lot of insulin to make the blood sugar down to the normal range. Diabetic patients due to the lack of pancreatic islet function and / or the body of insulin resistance, insulin secretion is insufficient and / or the body of insulin response insensitive, when consuming watermelon and other foods with high glycemic index, blood glucose rises significantly, and the body can not effectively reduce blood glucose. Diabetic patients with dietary health knowledge, can consult a professional nutritionist, under the guidance of the physician reasonable diet.