The feto-placental 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-placental 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-induced model of the feto-placental glucose steal phenomenon. Whole body glucose kinetics and glucose uptake into individual tissues were measured in anaesthetised rats basally and during hyperinsulinaemic euglycaemic clamps. The basal glucose metabolism of the pregnant rats was closely mimicked by the phlorizin-treated rats. Basal plasma glucose was 39% and 38% lower (p < 0.0001 for both); hepatic glucose production was 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 phlorizin-treated rats, respectively, compared to the control rats. Basal glucose uptake into peripheral tissues was lower in both the pregnant and phlorizin-treated compared to the control rats, being most evident in heart (p < 0.01 for both) and brown adipose tissue (p < 0.001 for both). In the clamp studies, impairment of glucose uptake into skeletal muscle was observed in both the pregnant and phlorizin-treated rats compared to the control rats. In conclusion, the feto-placental glucose 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 uptake.