Glucose Replacement to Euglycemia Causes Hypoxia, Acidosis, and Decreased Insulin Secretion in Fetal Sheep With Intrauterine Growth Restriction

Nutritional interventions for intrauterine growth restriction (IUGR) have raised concerns for fetal toxicity, the mechanisms of which are unknown. Most of these attempts did not aim to normalize fetal metabolic conditions. Therefore, we used a model of IUGR to determine whether normalization of fetal hypoglycemia for 2 wks would be tolerated and increase insulin concentrations and pancreatic β-cell mass. IUGR fetuses received either a direct saline infusion (Sal, the control group) or a 30% dextrose infusion (Glu) to normalize glucose concentrations. Neither insulin concentrations (0.11 ± 0.01 Glu vs. 0.10 ± 0.01 ng/mL Sal) nor β-cell mass (65.2 ± 10.3 Glu vs. 74.7 ± 18.4 mg Sal) changed. Glucose stimulated insulin secretion (GSIS) was lower in the Glu group. Glu fetuses became progressively more hypoxic: O2 content 1.4 ± 0.5 Glu vs. 2.7 ± 0.4 mM Sal, p < 0.05. Partial pressure of carbon dioxide (Paco2) (53.6 ± 0.8 Glu vs. 51.6 ± 0.8 Sal, p < 0.05) and lactate (7.74 ± 3.82 Glu vs. 2.47 ± 0.55 mM Sal, p < 0.0001) were greater and pH lower (7.275 ± 0.071 Glu vs. 7.354 ± 0.003 Sal, p < 0.01) in the Glu group. We conclude that correction of fetal hypoglycemia is not well tolerated and fails to increase insulin concentrations or β-cell mass in IUGR fetuses.