In addition to investigating the potential correlation between the frequency of Tfh and IL-21+ memory T cells, we investigated whether differential expression of IL-21 in type 1 diabetes patients could be caused by an altered T central memory (Tcm) cell compartment, a subset that has been recently found to have a higher proportion of IL-21-producing cells compared with the T effector memory (Tem) subset [14]. This evidence concerns the gene IL21 and type 1 diabetes mellitus.