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 ± 0.9 mM (mean ± SD); age: 31 ± 6 years; body mass index (BMI): 31.6 ± 6.4 kg/m(2) ; haemoglobin A1c (HbA1c): 5.6 ± 0.5%] and eight pregnant women with NGT (PG120min, OGTT : 5.7 ± 0.7 mM; age: 28 ± 3 years; BMI: 29.7 ± 5.4 kg/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 ± 3.2 nM × min, p=0.005], but the difference among NGT women (7.3 ± 2.8 vs. 8.8 ± 2.0 nM × min, 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.