Reduced postprandial GLP-1 responses in women with gestational diabetes mellitus

Aim: We investigated postprandial glucagon-like peptide-1 (GLP-1) responses in pregnant women with and without gestational diabetes mellitus (GDM) and again following delivery when normal glucose tolerance (NGT) was re-established. Methods: Eleven women with GDM [plasma glucose (PG) concentration at 120 min after a 75-g oral glucose tolerance test (OGTT): 10.0 +/- 0.9mM (mean +/- SD); age: 31 +/- 6years; body mass index (BMI): 31.6 +/- 6.4kg/m(2); haemoglobin A1c (HbA1c): 5.6 +/- 0.5%] and eight pregnant women with NGT (PG(120min, OGTT): 5.7 +/- 0.7mM; age: 28 +/- 3years; BMI: 29.7 +/- 5.4kg/m(2); HbA1c: 5.4 +/- 0.3%) were investigated with a 4-h liquid meal test during third trimester (TT) and 3-4 months postpartum (PP). All patients with GDM re-established NGT following delivery. Results: Pregnancy was associated with low postprandial GLP-1 responses. Patients with GDM exhibited reduced postprandial GLP-1 responses compared to their PP levels [area under curve (AUC): 5.5 +/- 1.3 vs. 8.4 +/- 3.2nMxmin, p=0.005], but the difference among NGT women (7.3 +/- 2.8 vs. 8.8 +/- 2.0nMxmin, p=0.066) was not statistically significant. Pregnancy did not influence postprandial responses of the other incretin hormone glucose-dependent insulinotropic polypeptide (GIP) in any of the groups, but GDM patients were characterized by greater postprandial GIP responses during both TT and PP compared to NGT subjects. Conclusions: Pregnancy is associated with reduced postprandial GLP-1 responses (most pronounced in patients with GDM) that normalize after delivery. In contrast, postprandial GIP responses seem unaffected by pregnancy but is increased in GDM patients.