Drinking water has little effect on the glucose tolerance and can be done, but if you eat, it will have a great impact, so it is recommended to have the glucose tolerance test another day. The main purpose of glucose tolerance is to check whether there is a possibility of gestational diabetes in pregnant women. If the increase is not much, diet can be adjusted to improve, but the blood glucose value should be checked, if it is too high, insulin should be used to control the blood glucose, because high blood glucose will lead to changes in the sclerosis of blood vessels, which will lead to symptoms of hypoxia, which will lead to intrauterine distress of the fetus, and also the possibility of a huge baby, which also increases the probability of hypoglycemia in the newborn. Therefore, it is necessary to control the diet during pregnancy and avoid excessive intake to prevent serious consequences.