Objective To investigate the role of antigen-specific regulatory T cells in spontaneous diabetes of NOD mice. Methods Glutamic acid decarboxylase (GAD)-peptide specific T cells with fluorescein-labelled Class Ⅱ MHC tetramers were isolated by flow cytometer from NOD mice with spontaneous diabetes and diabetes resistant BALB/c mice. The cytokine profiles of these T cells were detected by antigen stimulated assay, ELISA and intracellular cytokine staining. Adoptively transferred diabetes was determined by intravenously injecting these T cells to NOD/scid mice. Results With different peptides working on the same strain, it showed that NOD mice-derived T cells secreted different amounts of interforn-? but comparable interlenkin (IL)-4 or IL-10, however, similar cytokine profiles were shown in BALB/c mice-derived T cells. With the same peptide working on different strains, NOD mice-derived T cells secreted less IL-2 but more IL-4 and IL-10 than BALB/c mice-derived T cells did. Interestingly, these NOD mice-derived T cells effectively inhibited diabetes development in adoptively transferred NOD/scid mice. Conclusion NOD mice-derived T cells inhibit development of diabetes, however, different cytokine profiles are expressed by these T cells induced by two adjacent GAD peptides. It suggests that these T cells are diabetes-inhibiting regulatory T cells displaying unique cytokine profiles.