Screening for gestational diabetes mellitus is usually performed between 24 and 28 weeks of pregnancy. Currently, it is generally recommended that all pregnant women undergo an OGTT test, an oral glucose tolerance test, to clarify the presence of gestational diabetes. The common method of the OGTT test is: fasting for 12 hours, measure fasting blood glucose once, then take a glass of 300 ml of water, add 75 grams of glucose, mix well and drink, wait until the water is finished to measure blood glucose at intervals of 1 hour and 2 hours. Under normal circumstances, fasting blood glucose, 1 hour after taking sugar, 2 hours of blood glucose values below 5.1mmol / L, 10.0mmol / L, 8.5mmol / L. Any point of blood glucose value reaches or exceeds the above criteria will be diagnosed as gestational diabetes mellitus. Pregnant women with gestational diabetes mellitus need dietary management, appropriate exercise, insulin to control blood glucose if necessary, and close monitoring of the mother and child.