Glucose production by the human placenta in vivo

The human placenta transports glucose by facilitated diffusion down a conce ntration gradient from mother to fetus. It has previously been considered i ncapable of glucose synthesis. However, recent work has demonstrated the pr esence in placental tissue of glucose-6-phosphatase, which is required for the final step in the synthesis of glucose. Following continuous intravenou s infusion into the maternal circulation of the stable isotope, 6,6-H-2(2) glucose, during elective caesarean section, we have observed isotope diluti on in the umbilical vein, without further dilution in the umbilical artery. Using a mathematical model containing maternal, placental and fetal compar tments, the data were compatible with the release of glucose by the placent a. We conclude that the human placenta at term can produce glucose. (C) 199 9 Harcourt Publishers Ltd.