Glucose tolerance refers to an oral glucose tolerance test, which is usually an arm draw. Oral glucose tolerance test belongs to a kind of glucose loading test, usually, oral glucose tolerance test is through the vein blood collection method, is drawn arm, rather than sticking the finger, mainly because the accuracy of detecting the blood of the end of the limbs is higher than the test results on the finger tip. The oral glucose tolerance test involves dissolving 75g of glucose in 250-300ml of water and drinking it within 5 minutes, before taking it, and 30 minutes, 1 hour, 2 hours, and 3 hours after taking it for venous glucose, respectively. It should be noted that no calorie intake is allowed for 8 hours before the test. Normally, fasting blood glucose should be between 3.9 and 6.1 mmol/L, and 2-hour postprandial blood glucose should be less than 7.8 mmol/L. Diabetes mellitus is diagnosed if the 2-hour glucose of glucose tolerance test is ≥11.1 mmol/L, accompanied by typical symptoms of diabetes mellitus. If the glucose tolerance test is abnormal, it is recommended to seek prompt medical attention and follow the doctor’s instructions.