The normal range of blood glucose in pregnant women is 3.1-5.1 mmol/L. Since gestational diabetes poses a great risk to both the mother and the fetus, especially when blood glucose is not satisfactorily controlled, it may even endanger the life of the mother as well as the fetus. Therefore, it is important to pay attention to timely screening during pregnancy, and screening for diabetes is required between 24-26 weeks. Screening for diabetes is generally divided into two methods: 1) direct 75g glucose tolerance test, which requires monitoring fasting blood glucose and blood glucose values one hour and two hours after taking glucose. 2) by first monitoring fasting blood glucose or blood glucose values after taking 50g of glucose orally. If there is any abnormality, the diagnosis of gestational diabetes will be made directly; if there is no abnormality, a further 75g glucose tolerance test will be performed.