By searching for TCRB CDR3 sequences from induced bifunctional CD4 T cell clone responses in a repository of TCR sequences from circulating naive and central memory CD4+ T cell subsets from individuals with new-onset type 1 diabetes and healthy individuals we were able to show that numerous GAD-specific clonotype signatures are public, being present in multiple people; and not disease-specific, being present in both those with diabetes and the healthy control individuals. Here, GAD1 is linked to type 1 diabetes mellitus.