THE FETOPLACENTAL GLUCOSE STEAL PHENOMENON IS A MAJOR CAUSE OF MATERNAL METABOLIC ADAPTATION DURING LATE PREGNANCY IN THE RAT

The aim of this study was to determine the extent to which a feto-plac ental glucose steal phenomenon contributes to the process of maternal metabolic adaptation to late pregnancy. Glucose metabolism was studied in virgin control, pregnant rats and virgin rats with a phlorizin-ind uced model of the fete-placental glucose steal phenomenon. Whole body glucose kinetics and glucose uptake into individual tissues were measu red in anaesthetised rats basally and during hyperinsulinaemic euglyca emic clamps. The basal glucose metabolism of the pregnant rats was clo sely mimicked by the phlorizin-treated rats. Basal plasma glucose was 39% and 38% lower (p < 0.0001 for both); hepatic glucose production wa s 21% and 26% higher (p < 0.05 for both); and plasma glucose clearance was 109% and 104% higher (p < 0.0001 for both) in the pregnant and ph lorizin-treated rats, respectively, compared to the control rats. Basa l glucose uptake into peripheral tissues was lower in both the pregnan t and phlorizin-treated compared to the control rats, being most evide nt in heart (p < 0.01 for both) and brown adipose tissue (p < 0.001 fo r both). In the clamp studies, impairment of glucose uptake into skele tal muscle was observed in both the pregnant and phlorizin-treated rat s compared to the control rats. In conclusion, the fete-placental gluc ose steal phenomenon is a major contributing factor to postabsorptive glucose metabolism in late pregnancy. This phenomenon also contributes to the impairment of maternal insulin-stimulated peripheral glucose u ptake.