The concept of gestational diabetes mellitus: 1, diabetes mellitus combined with pregnancy: the original diabetes mellitus on the basis of pregnancy; 2, diabetes mellitus during pregnancy: diabetes mellitus diagnosed according to ordinary diabetes mellitus standards during pregnancy, also known as overt diabetes mellitus; 3, gestational diabetes mellitus: diabetes mellitus diagnosed according to gestational diabetes mellitus standards during pregnancy. Diagnostic criteria for gestational diabetes mellitus: fasting blood glucose ≥5.1mmol/L, OGTT1h blood glucose ≥10.0mmol/L, OGTT2h blood glucose ≥8.5mmol/L; Methods: 75g glucose tolerance test is mostly used. It refers to the oral administration of 75g of glucose after 12 hours of fasting, and its upper limit of normal is 5.6mmol/L for fasting, 10.3mmol/L for 1hour, 8.6mmo1/L for 2hours, and 6.7mmol/L for 3hours. 2 or more of these items are at or above the normal value, and the diagnosis of gestational diabetes can be made. Abnormal glucose tolerance was diagnosed when only 1 was above normal. Family history of diabetes mellitus, age >30 years, obesity, history of delivery of a giant baby, history of recurrent unexplained miscarriages, stillbirths, stillbirths, delivery of a child with full-term neonatal respiratory distress syndrome, and history of fetal anomalies. Criteria for the control of gestational diabetes mellitus: fasting <5.3 mmol/L, 1h postprandial <7.8 mmol/L, 2h postprandial <6.7 mmol/L.