Fasting blood glucose decreases by about 10% in the early and middle stages of pregnancy, and the sensitivity of pregnant women to insulin decreases in the middle and late stages of pregnancy, which can cause an increase in blood glucose if it is not compensated for properly. In the early and middle stages of pregnancy, with the increase of gestational weeks, the fetus’s demand for nutrients increases, through the placenta from the mother to obtain glucose is the main source of fetal energy, pregnant women’s plasma glucose levels with the progress of pregnancy and decrease, fasting blood glucose decreased by about 10%. In the middle and late stages of pregnancy, the pregnant woman’s body antagonizes the increase of insulin-like substances, so that the pregnant woman’s sensitivity to insulin decreases with the increase of gestational weeks, in order to maintain the normal glucose metabolism level, the insulin demand must be increased accordingly. For pregnant women with limited insulin secretion, they cannot compensate for this physiological change during pregnancy and may develop gestational diabetes or aggravate their existing diabetes. High or low blood glucose during pregnancy should be taken seriously. When abnormal blood glucose during pregnancy occurs, it is recommended to consult a doctor in time, follow the doctor’s instructions for further examination, and under the doctor’s comprehensive analysis, choose a reasonable treatment plan.