ASSESSMENT OF THERAPY IN GESTATIONAL DIABETES BY SUBSTRATE AND HORMONE RESPONSES TO A STANDARDIZED TEST MEAL

Postprandial substrate and hormone responses to a standard mixed meal (400 kcal) was determined at two occasions, A and B, in 11 women with gestational diabetes (GDMs) and 11 normoglycaemic controls, matched fo r age, body mass index, and gestational age. Levels of circulating glu cose, non-esterified fatty acids (NEFA), glycerol, 3-hydroxybutyrate ( 3-HBA), individual amino acids, insulin, and C-peptide were analysed. A was performed when GDMs were considered inadequately controlled with diet alone, B later during gestation following initiation of insulin therapy because of hyperglycaemia. Fasting glucose, glycerol, total an d individual amino acids (alanine, valine, isoleucine, leucine), insul in, and C-peptide were not different from normal during A and B, neith er were postprandial amino acid levels. During test A, GDMs had elevat ed fasting and postprandial 3-HBA (p < 0.001), greater postprandial ri se of glucose (p < 0.001), elevated NEFA (p < 0.05), but normal and pa rallel decreases of NEFA and glycerol. Insulin and C-peptide responses were delayed and prolonged. During B, GDMs had higher glucose respons e (p < 0.005), higher fasting 3-HBA (p < 0.02) but similar and paralle l decreases of NEFA, glycerol, and 3-HBA as controls. The C-peptide re sponse was not significantly different from normal; insulin response w as higher (p < 0.05). in conclusion, the relative insulin deficiency c haracterizing GDMs, also when treated with insulin, is associated with selected defects in insulin action; mainly affecting glucoregulation, whereas suppression of lipolysis and proteolysis remain normal. (C) 1 997 by John Wiley & Sons, Ltd.