Incretin hypersecretion in gestational diabetes mellitus

Background Incretins are crucial stimulators of insulin secretion after food intake. We investigated the incretin response during an oral glucose tolerance test in pregnant women with and without gestational diabetes. Methods Subjects underwent a 5-point OGTT with 75 g glucose. We assessed insulin secretion and levels of total GLP-1, GIP, glicentin and glucagon during the OGTT. Findings We examined 167 women (33 with GDM) during gestational week 26.95 (2.15 SD). Insulin secretion was significantly lower in women with GDM (p<0.001). Postprandial GLP-1 and GIP were ~20% higher in women with GDM (all p<0.05) independent from age, BMI and gestational age. GLP-1 increase associated with insulin secretion only in GDM, but not in NGT. Postprandial GLP-1 levels associated negatively with birth weight. Interpretation The more pronounced GLP-1 increase in women with GDM could be part of a compensatory mechanism counteracting GLP-1 resistance. Higher GLP-1 levels might be protective against fetal overgrowth.