CXCR5 and type 1 diabetes mellitus: It is possible that Tfh cells may play a critical role in the initial stages of T1D with an increase of activated CXCR5+PD-1+ICOS+ cTfh cells being found in both children with newly diagnosed T1D and in children at late stages of preclinical T1D, characterized by impaired glucose tolerance (247, 248).