GDM is an abbreviation for gestational diabetes mellitus, as the name implies, patients have abnormal glucose metabolism during pregnancy, and gestational diabetes mellitus is a follow-up diagnosis. Gestational diabetes can be diagnosed if the patient did not have diabetes before pregnancy, but after pregnancy, abnormal glucose metabolism occurs, with fasting glucose ≥ 5.1 mmol/L, or 1 hour postprandial glucose ≥ 10.0 mmol/L, or 2 hours postprandial glucose ≥ 8.5 mmol/L. Patients with elevated blood glucose during pregnancy can have adverse effects on the pregnant woman as well as the fetus if left uncontrolled. For pregnant women, they are prone to miscarriage and preterm delivery. It can also lead to various acute complications of diabetes, such as ketoacidosis, in which patients may exhibit nausea, vomiting, drowsiness, deep and rapid breathing, and exhaled gas that smells like rotten apples, or skin boils and carbuncles, in which patients may have red, swollen, hot, painful and abscessed skin. For the fetus, it is prone to fetal malformation, giant fetus, and neonatal hypoglycemia at birth. When patients develop gestational diabetes, they should be given dietary control, avoiding high-sugar foods such as cakes and milk tea, as well as proper exercise, such as slow walking. If the patient’s blood sugar is still not up to standard after diet and exercise control, then insulin is needed for control. For gestational diabetes, patients can generally only be treated with insulin and not with oral hypoglycemic drugs, which can cause adverse effects on the fetus through the placenta, such as fetal miscarriage and fetal malformation. For patients with gestational diabetes, the blood glucose of most patients can return to normal after 6 weeks of delivery.