There are two types of diabetes mellitus during pregnancy, one is diabetes mellitus diagnosed before pregnancy, called “diabetes mellitus combined with pregnancy”; the other is diabetes mellitus with normal glucose metabolism before pregnancy or potentially reduced glucose tolerance, but only developed or diagnosed during pregnancy, also known as “gestational diabetes mellitus (GDM)”. “GDM. The incidence of GDM is reported to be 1%-14% in the world, and 1%-5% in China, with a significant increase in recent years. most patients with GDM can return to normal glucose metabolism after delivery, but the chance of developing type II diabetes increases in the future. The clinical course of pregnant women with diabetes mellitus is complex, and both mother and child are at risk, so attention should be paid. Etiology In the early and middle stages of pregnancy, as the gestational weeks increase, the fetal demand for nutrients increases, and the acquisition of glucose from the mother through the placenta is the main source of fetal energy. The plasma glucose level of pregnant women decreases with the progress of pregnancy, and fasting glucose decreases by about 10%. Reasons: increased fetal glucose acquisition from the mother; increased renal plasma flow and glomerular filtration rate during pregnancy, but the renal tubular reabsorption rate of sugar cannot be increased accordingly, resulting in increased glucose excretion in some pregnant women; estrogen and progesterone increase the maternal utilization of glucose. Therefore, the ability of pregnant women to clear glucose during fasting is enhanced compared with non-pregnancy. The fasting glucose of pregnant women is lower than that of non-pregnant women, which is also the pathological basis for the vulnerability of pregnant women to hypoglycemia and ketoacidosis during prolonged fasting. In the middle and late stages of pregnancy, the anti-insulin-like substances in pregnant women increase, such as placental lactogen, estrogen, progesterone, cortisol and placental insulinase, which make the sensitivity of pregnant women to insulin decrease with the increase of gestational weeks. In order to maintain normal glucose metabolism level, insulin requirement must increase accordingly. For pregnant women with limited insulin secretion, pregnancy cannot compensate for this physiological change and increases blood glucose, worsening existing diabetes or causing GDM. Effects of pregnancy on diabetes Pregnancy can make latent diabetes manifest, causing GDM to occur in pregnant women without previous diabetes and worsening the condition of patients with existing diabetes. Fasting blood sugar is low in early pregnancy, and some patients may develop hypoglycemia if the insulin dosage is not adjusted in time for pregnant women treated with insulin. As pregnancy progresses, anti-insulin-like substances increase and insulin dosage needs to be increased continuously. During delivery, physical exertion is high and the amount of food eaten is low. If the insulin dosage is not reduced in time, hypoglycemia may easily occur. After delivery, the placenta is expelled from the body and the anti-insulin substances secreted by the placenta disappear rapidly, so the insulin dosage should be reduced immediately. Due to the complex changes of glucose metabolism during pregnancy, if the insulin dosage is not adjusted in time for pregnant women treated with insulin, some patients may experience hypoglycemia or hyperglycemia, which may even lead to hypoglycemic coma and ketoacidosis in serious cases. The impact of diabetes on pregnancy The impact of gestational combined diabetes on mother and child and the degree of impact depends on the condition of diabetes and the level of glycemic control. In severe cases or poor glycemic control, the impact on the mother and child is extremely high, and the near-term and long-term complications for the mother and child remain high.