GAD1 and type 1 diabetes mellitus: We observed no significant differences in total, PTM GAD, or PTM IA2 specific T cell frequencies between high and low c-peptide groups (Supplemental Figure 5), but there was a trend toward higher PTM GAD frequencies in subjects with T1D (p=0.16) and we noticed that elevated PTM IA2 frequencies were exclusively seen in the c-peptide low group.