Glucose tolerance generally refers to the glucose tolerance test, which is usually done with 250 to 300 milliliters of water. The glucose tolerance test is performed on an empty stomach for at least 8 hours before the test, without food or water. The next day on an empty stomach, blood is drawn to check the fasting plasma glucose level, after which 75 grams of anhydrous glucose powder is dissolved in 250-300 milliliters of water and mixed, and the glass of water is finished within 5 minutes. Remember the time of drinking the first sip of sugar water, to draw blood for checking after 0.5 hours, 1 hour, 2 hours and 3 hours respectively, and not to eat any food again during the checking process in order to get the most realistic checking result. Patients who need to undergo glucose tolerance test examination are recommended to strictly follow the doctor’s instructions to water to avoid affecting the final test results.