Generally, it is recommended that pregnant women take a glucose tolerance test at around 24-28 weeks, when the placenta of pregnant women has strong secretion function and the test results are more accurate. In early pregnancy, the mother’s demand for sugar is relatively high, which can cause physiological blood sugar lowering, in which case the glucose tolerance test may mask the diagnosis of gestational diabetes mellitus in pregnant women. After 24 weeks, the placental secretion function is very strong, all kinds of unfavorable factors in the pregnant woman’s body that lead to diabetes are the most obvious, if the pregnant woman has abnormal glucose metabolism, it is easy to detect. If high blood glucose is detected, early intervention can be made to minimize the harm to the mother and child. If there is a family history of diabetes, obesity, or a previous history of gestational diabetes, delivery of a huge child, it is recommended that a diagnosis of diabetes be made at about 16 weeks of pregnancy. Do glucose tolerance test examination before three days of normal diet, fasting on the day of blood sampling, first take fasting blood glucose, blood sampling after drinking 75g glucose powder plus 300ml of warm boiled water sugar solution, within 5 minutes to drink, and then in 1 hour, 2 hours later, respectively, blood sampling blood glucose value. Diagnostic criteria are fasting blood glucose at 5.1mmol/L, oral glucose tolerance test 1 hour blood glucose ≥ 10mmol/L, 2 hours blood glucose up to ≥ 8.5mmol / L, the above three points to meet one of the points can be diagnosed as gestational diabetes. Note that if the pregnant woman has a family history of diabetes mellitus or has given birth to a fetus with diabetes mellitus, as well as if the pregnant woman has impaired glucose tolerance before pregnancy, it is recommended that a glucose tolerance test be performed in early pregnancy.