GLUCOSE-TURNOVER AND GLUCONEOGENESIS IN HUMAN-PREGNANCY

The rate of appearance (Ra) of glucose in plasma and the contribution of gluconeogenesis were quantified in normal pregnant women early (sim ilar to 10 wk) and late (similar to 34 wk) in gestation, Their data we re compared with those of normal nonpregnant women, Glucose Ra was mea sured using the [U-C-13]glucose tracer dilution method, Gluconeogenesi s was quantified by the appearance of H-2 On carbon 5 and 6 of glucose after deuterium labeling of body water pool, Weight-specific glucose Ra was unchanged during pregnancy (nonpregnant, 1.89+/-0.24; first tri mester, 2.05+/-0.21; and third trimester 2.17+/-0.28 mg/kg min, mean+/ -SD), while total glucose Ra was significantly increased (early, 133.5 +/-7.2; late, 162.6+/-16.4 mg/min; P = 0.005), The fractional contribu tion of gluconeogenesis via pyruvate measured by H-2 enrichment on C-6 of glucose (45-61%), and of total gluconeogenesis quantified from H-2 enrichment on C-5 of glucose (i.e., including glycerol [68-85%]) was not significantly different between pregnant and nonpregnant women, In asmuch as total glucose Ra was significantly increased, total gluconeo genesis was also increased in pregnancy (early pregnancy, 94.7+/-15.9 mg/min; late pregnancy, 122.7+/-9.3 mg/min; P = 0.003), These data dem onstrate the ability of the mother to adapt to the increasing fetal de mands for glucose with advancing gestation, The mechanism for this uni que quantitative adjustment to the fetal demands remains undefined.