Glucose metabolism in pregnancy.

Pregnancy is characterized by a number of maternal metabolic modifications in order to meet the energy requirements of the growing fetus. A progressive alteration of maternal glucose homeostasis develops throughout gestation and becomes maximal during the last trimester. A relative hypoglycemia is observed during the postabsorptive period despite an elevated plasma insulin concentration and an enhanced hepatic glucose production. In addition, the glucose utilization rate by peripheral maternal tissues is lowered in late gestation indicating that the mother supplies glucose to the fetus at the expense of her own tissues. Concomitantly, an insulin-resistant state develops in the mother to help sparing glucose for the pregnant uterus. It involves both glucose-producing (liver) and glucose-utilizing tissues. So far, the factor(s) responsible for the development of pregnancy-induced insulin resistance has not been identified although a number of circulating hormones are known to counteract insulin effects.