Not most women have elevated blood glucose after pregnancy. In the early and middle stages of pregnancy, with the increase of gestational weeks, the fetus’s demand for nutrients increases, and glucose from the mother through the placenta is the main source of energy for the fetus, and the plasma glucose level of pregnant women decreases with the progression of pregnancy, and fasting blood glucose decreases. Because of the increase in fetal glucose acquisition from the mother; estrogen and progesterone increase maternal utilization of glucose. By the middle and late stages of pregnancy, the increase of antagonistic insulin-like substances in pregnant women, such as tumor necrosis factor, leptin, placental prolactin, estrogen, progesterone, cortisol, and placental insulinase, etc. make pregnant women’s sensitivity to insulin decreases with the increase of gestational weeks, and in order to maintain the normal level of glucose metabolism, the demand for insulin must be increased accordingly. For pregnant women with limited insulin secretion, pregnancy can not compensate for this physiological change and increase blood glucose, the emergence of gestational diabetes mellitus or aggravation of the original diabetes mellitus. Therefore, not most women will have elevated blood sugar after pregnancy. Pregnant women with blood glucose abnormalities are advised to seek medical attention.