Longitudinal Changes in Amino Acid (AA) Turnover in Pregnancy in Women with Normal Glucose Tolerance (NGT) and GDM—Relationship to Fetal Growth

GDM have decreased glucose insulin sensitivity vs. NGT. However, there are less data on the impact of GDM on AA metabolism or relationship to fetal growth. Ten NGT and 8 GDM (≥ 1 abnormal value, 3 hour OGTT) were evaluated at 18-22 and 32-36 weeks for 2 potent amino acid secretogogues, Phenylalanine (PHE) and Leucine (LEU). PHE and LEU turnover was estimated (D5 PHE and 13C LEU) under basal and euglycemic hyperinsulinemic clamp conditions. Neonatal body composition was estimated using anthropometrics. There were no significant difference in maternal age, race, education, tobacco use, weight or body composition between GDM and NGT at 18-22 weeks. The was a higher family hx of diabetes in GDM (p=0.05). Basal LEU but not PHE turnover increased over time and was greater in GDM, Table. Glucose disposal decreased over time and was lower in GDM. During the clamp LEU but not PHE turnover increased over time and was greater in GDM. Clamp PHE turnover (µmol/kg/hour) at 18-22 weeks correlated with neonatal lean mass (r=0.48, p=0.048) and there was a trend for fat mass (r=0.47, p=0.058). Omitting 1 outlier there remained a trend for PHE turnover and neonatal lean mass (r=0.43, p=0.09). Leu turnover increased over time and was greater in GDM vs. NGT. In contrast, there were no significant changes in PHE turnover over time or between groups but PHE turnover in early pregnancy was related to fetal lean mass.