Protein metabolism in insulin-treated gestational diabetes.

OBJECTIVE: To test the hypothesis that protein metabolism is not totally normalized in insulin treated gestational diabetes mellitus (GDM) patients compared with normal, pregnant control subjects. RESEARCH DESIGN AND METHODS: Protein metabolism in eight Hispanic women with insulin-treated GDM and eight healthy Hispanic control women was studied in late gestation and at 6 weeks postpartum. Nitrogen flux was assessed from the disposal rate of [15N]-labeled urea over 12 h after a dose of [15N]-labeled leucine. Plasma amino acid concentrations were determined in fasting and 2-h postprandial samples using an amino acid analyzer.
RESULTS: Protein turnover was normalized in insulin-treated GDM; however, fasting and postprandial plasma amino acids were elevated antepartum and postpartum. Nitrogen flux was significantly lower during pregnancy (P = 0.04-0.001) and did not differ between groups. Fasting and postprandial plasma amino acids were elevated in GDM antepartum and postpartum, despite satisfactory glycemic control. Fasting levels of taurine, hydroxyproline, glutamic acid, glutamine, cystine, tyrosine, phenylalanine, tryptophan, and histidine were higher in GDM antepartum and postpartum (P < 0.05). Postprandial concentrations of taurine, hydroxyproline, valine, cystine, isoleucine, leucine, tyrosine, phenylalanine, tryptophan, ornithine, lysine, histidine, and arginine were higher in GDM antepartum and postpartum (P < 0.05). With few exceptions, plasma amino acid concentrations were lower antepartum than postpartum (P < 0.05).
CONCLUSIONS: Protein turnover was normalized in insulin-treated women with GDM; however, fasting and postprandial plasma concentrations of amino acids were elevated in the antepartum and postpartum periods, despite satisfactory maternal glycemic control.