The latest standard for glucose tolerance test for pregnant women is to fast for 8-12 hours before the test and measure fasting blood glucose first, which should be <5.1mmol/L for fasting, <10.0mmol/L for 1 hour after drinking 75g of glucose and <8.5mmol/L for 2 hours. If any of the above three tests is at or greater than the standard, gestational diabetes can be diagnosed. If the results of all three tests are within the normal range, it means that the glucose tolerance is normal. In case of gestational diabetes, there is a risk of giant fetus, delayed fetal lung development, intrauterine hypoxia, maternal hyperosmolar coma and ketoacidosis. Before the glucose tolerance test for pregnant women, the daily consumption of carbohydrates should be at least 150g, and normal physical activity is required for at least 3 days, so that the normal diet and physical activity can be maintained, as a way to keep the organism in the same state as the daily, which is more conducive to the authenticity of the test results. The main purpose of the glucose tolerance test for pregnant women is to confirm the presence of diabetes and to understand the fluctuation of blood sugar. Tea and coffee should be banned before the glucose tolerance test because they contain exciting substances.