Glucose tolerance generally refers to the oral glucose tolerance test, and vomiting during the test may have some effect on the results of the second blood draw. The oral glucose tolerance test requires a certain amount of glucose to be taken before the test, and blood is drawn on an empty stomach, 30 minutes, 1 hour, 2 hours, and 3 hours after the glucose is taken to check the blood glucose level. If you vomit during the test, you will vomit the glucose that should have been digested and absorbed into your body, and your body will not convert this glucose, which may affect the results of the second blood test. If vomiting occurs during the oral glucose tolerance test, you need to inform your doctor in time and ask him/her to make a judgment.