CXCR5 and type 1 diabetes mellitus: In this study, we performed an extensive analysis of CXCR5−PD‐1hi cTph and CXCR5+PD‐1hi cTfh cells at the single‐cell level to elucidate outstanding questions on the timing of their emergence during T1D autoimmunity, cellular heterogeneity, and relationship with each other.