Plasma amino acid, glucose, and insulin responses to moderate-protein and high-protein test meals in pregnant, nonpregnant, and gestational diabetic women.

Test meals providing two levels of dietary protein (13% or 26% of the energy) were fed to eight pregnant (P), nine nonpregnant (NP), and two gestational diabetic (GDM) women. Plasma levels of amino acids were measured at 0 h and 2 h. Glucose and insulin were measured at 0, 1/2, and 2 h after the meals. In the fasting state, P women had significantly lower fasting concentrations of most of the amino acids. After the high-protein meal, rises of arginine, ornithine, and branched-chain amino acids (BCAAs: leucine, isoleucine, and valine), were significantly smaller in P women. Changes in BCAAs were normal in GDM women. P women had greater rises of insulin in response to both test meals than did NP women. This may facilitate increased BCAA uptake from the circulation. Rises in plasma glucose tended to be higher in P than NP women, suggesting that insulin's effects on glucose and BCAA uptake may be mediated separately.