The aim of our study was to compare the secretion of amylin, as well as glucose, insulin and C-peptide at baseline and in response to glucagon stimulation in 26 lean women with gestational diabetes mellitus (GDM) and in 19 age- and BMI-matched pregnant women with normal glucose tolerance (NGT). Intravenous 1-mg glucagon stimulation test was performed 6 weeks after delivery. Fasting and stimulated glucose levels were significantly higher in GDM patients than in subjects with NGT ( p<0.01 at 0 and 6 min; glucose area under the curve (AUC), 604.8+/-41.8 mg/6 min vs. 572.4+/-52.4 mg/6 min, p<0.05). Insulin AUC was also markedly higher in GDM subjects than in healthy controls (373.9+/-144.2 micro IU/6 min vs. 283.7+/-139.1 micro IU/6 min, p<0.05). There was no difference in fasting C-peptide levels between the groups studied, but stimulated concentrations, as well as C-peptide AUC were significantly higher in patients with GDM ( p<0.01 at 1 min and p<0.005 at 6 min; AUC, 27.4+/-11.3 pmol/6 min vs. 18.4+/-6.9 pmol/6 min, p<0.01). Amylin levels were higher in GDM group in comparison to healthy subjects ( p<0.005 at 1 and 6 min; amylin AUC, 113.3+/-51.2 pg/6 min vs. 72.5+/-15.7 pg/6 min; p=0.14), but in contrast to the other hormones, did not rise in response to glucagon injection. In conclusion, our results provide evidence that in patients with GDM in the post-partum period, the levels of amylin, as well as the secretion of insulin and C-peptide remain elevated, when compared to women with NTG. Further investigations are needed to clarify the significance of this elevation as a predictive factor for the development of late maternal type 2 diabetes.