After pregnancy, women need to bear the energy required for the development of the embryo, so the blood glucose metabolism of pregnant women is different from that of normal people, especially in the middle and late stages of pregnancy. At present, it is believed that the middle and late stages of pregnancy are the most vulnerable period for pregnant women to develop gestational diabetes. The reasons for this can be categorized as follows: 1. As pregnancy progresses, the capacity required for embryonic development gradually increases. The way the embryo solicits energy from the mother is achieved by transporting glucose in the blood. Therefore, the supply of glucose from the mother to the fetus gradually increases as the pregnancy progresses. Pregnant women have lower blood glucose than the normal population. 2. In the middle and late stages of pregnancy, there is a gradual increase in the number of insulin-resistant substances in the mother’s blood. These substances have the effect of antagonizing insulin. Therefore, pregnant women in the middle and late stages of pregnancy need more insulin to lower their blood sugar levels. In this case, if the secretion of insulin is not supplied adequately, then gestational diabetes occurs. In the middle and late stages of pregnancy, it is a test of the insulin secretion function of the mother’s organism. To summarize, the middle and late stages of pregnancy are the stages that are prone to gestational diabetes and need to be taken seriously by all pregnant women.