The slightly longer proinsulin peptide (C19-A3) that was used in a phase 1b immunotherapy trial of adult newly diagnosed T1D patients seemed to result in higher residual C-peptide compared to those on placebo, no increase in insulin dose, higher FoxP3 expression in CD45RA− Tregs, proinsulin-elicited IL-10 production by CD4+ T cells, baseline levels of β-cell specific CD8+ T cells, and favorable proinsulin/C-peptide ratio [47]. Here, CD4 is linked to type 1 diabetes mellitus.