1, patients no longer eat drugs after dinner the day before the examination to the next day before the examination, overnight fasting for 10-14 hours, you can drink water. 2.After drawing fasting blood, take 300 ml of water containing 75 grams of glucose by mouth or eat 100 grams of flour buns, record accurately the time after taking sugar or eating buns, and draw blood on time at half an hour, one hour, two hours and three hours respectively. 3.Do not eat or take drugs during the test. 4, three days before the test must be normal activities, normal diet. 5.Disease and trauma, such as fever, acute cardiovascular disease, etc., put the body in a state of stress, which may cause a temporary increase in blood glucose and a decrease in glucose tolerance. This test should be done when normal activities are resumed after recovery. 6, drug influence, such as corticosteroid, growth hormone can raise blood sugar, while ethanol, tabazol, monoamine oxidase inhibitors can lower blood sugar.