In patients with type 2 diabetes: fasting C-Peptide and 1-h-postprandial C-Peptide levels in subgroup GAD-Ab (+) = 0, 71 ± 0, 6 và = 2, 81 ± 1, 84 were not significantly different with those of subgroup GAD-Ab (-) = 1, 11 ± 0, 77 and = 3, 33 ± 2, 22 respectively. Conclusions: The percentage of GAD-Ab (+) among patients with newly diagnosed type 2 diabetes was 9%.