Gestational diabetes mellitus (GDM) is diabetes that first occurs or is detected during pregnancy and includes a subset of patients who had diabetes before pregnancy but were diagnosed for the first time during pregnancy. The World Health Organization classified GDM as a separate type of diabetes in 1979. The screening method is simple: a pregnant woman measures her blood glucose after drinking 50 grams of glucose – the 50g glucose stress test (GCT). The specific methods are: i. Timing of 50gGCT All non-diabetic pregnant women should have 50gGCT routinely done at 24 to 28 weeks of gestation. Pregnant women with the following high-risk factors for GDM should have 50gGCT at their first pregnancy checkup, and those with normal blood glucose at this stage should repeat 50gGCT after 24 weeks of gestation. high-risk factors for GDM include: obesity, family history of diabetes, polycystic ovarian syndrome, positive fasting urine glucose in early pregnancy, history of delivery of a giant baby, history of GDM, history of multiple spontaneous abortions with no apparent cause, history of fetal malformation, history of stillbirth, and history of delivery of a full-term newborn with respiratory distress syndrome. It is especially important to emphasize that those with high-risk factors should receive 50gGCT early in pregnancy for timely diagnosis. Second, should I drink glucose on an empty stomach for the 50gGCT method? When should I drink it? The guidelines stipulate that 50g of glucose (dissolved in 200ml of water and taken within 5 minutes) should be taken orally at random, and venous blood or micro-end blood glucose should be drawn 1 hour after taking the glucose to check blood glucose. Blood glucose ≥ 7.8 mmol/L (140 mg/dl) is abnormal for 50gGCT and further 75g glucose tolerance test (OGTT) should be performed; pregnant women with 50gGCT 1-hour blood glucose ≥ 11.1 mmol/L (200 mg/dl) should first check fasting blood glucose (FPG), and FPG ≥ 5.8 mmol/L (105 mg/dl). It is not necessary to do OGTT, and for those with normal FPG, OGTT should be done as early as possible. The guidelines clearly tell us that pregnancy is not suitable unless there are serious complications. Otherwise, pregnancy is still possible with good glycemic control. A thorough physical examination, including blood pressure, electrocardiogram, fundus, renal function, and glycosylated hemoglobin (HbA1c), should be performed before pregnancy to determine the grade of diabetes and decide whether pregnancy is possible. Patients with diabetes mellitus who have complicated severe cardiovascular disease, decreased renal function, or proliferative retinopathy in the fundus should use contraception, and if pregnancy has occurred, it should be terminated as soon as possible. In diabetic nephropathy, pregnancy is possible if the 24-hour urine protein quantification is less than 1g and the renal function is normal; or if the proliferative retinopathy has been treated. Diabetic patients who are preparing for pregnancy should have their blood glucose adjusted to normal levels and HbA1c reduced to less than 6.5% before pregnancy. Those who used oral hypoglycemic drugs before pregnancy should preferably switch to insulin to control blood glucose to or near normal before pregnancy. Special attention should be paid to diet control for those who are diagnosed with GDM in outpatient clinic, the patient is instructed to control diet and admitted to hospital. for GIGT, diet control can be performed in outpatient clinic, and FPG and 2 hours postprandial glucose are monitored, and those whose glucose is still abnormal are admitted to hospital. The difference between the diet part and non-pregnant period is that the daily calorie requirement of pregnant women should not only meet their own needs, but also meet the needs of the fetus. Total daily calories during pregnancy: 1800-2200 kcal, of which carbohydrates account for 45%-55%, protein 20%-25% and fat 25%-30%. Small amount and multiple meals should be implemented, divided into 5 to 6 meals per day. Special attention should be paid to pregnant women in middle and late pregnancy, whose daily supplementation should be 300 to 350 kcal more than that in non-pregnancy. In addition, the ratio of fat intake should be paid attention to. The intake of saturated fatty acids should not exceed 10% of the total calories; if there is already hyperlipidemia, it should not exceed 7%. Because of the changes in lipid metabolism after pregnancy, it makes some pregnant women prone to hyperlipidemia. Measurement of 24-hour blood glucose (blood glucose profile test) after 3 to 5 days of diet control: including blood glucose levels at zero hour, half an hour before and 2 hours after three meals and the corresponding urinary ketone bodies. A positive urinary ketone body after strict dietary control should lead to dietary readjustment. In addition, since the results of a prospective, randomized controlled study (RCT) based in the United States in 2000 have shown that second-generation oral hypoglycemic agents of the Juan Urea class are safe and effective for the treatment of mid- and late-stage diabetes in pregnancy, and subsequently many foreign medical centers have used the drug in clinical practice. Due to the lack of domestic experience with this drug in pregnancy, it is not included in this guideline for the time being, but it can be applied in clinical practice if there are eligible patients. Don’t forget to conduct postpartum follow-up All pregnant women with GDM should have their fasting blood glucose checked after delivery, and those with normal fasting blood glucose should have an oral 75 gram glucose tolerance test (fasting as well as blood glucose 2 hours after taking sugar) 6 to 12 weeks after delivery, and depending on the blood glucose level, the diagnosis of diabetes combined with pregnancy, impaired glucose tolerance (IGT) combined with pregnancy or GDM can be confirmed.