The frequency of CD25lowCD127lowFOXP3+ Tregs within the CD4+ compartment was slightly elevated in children with T1D (0.38 ± 0.17% vs. 0.29 ± 0.13% in healthy children, P < 0.01) but not in autoantibody-positive children (Figure 4C and Supplementary Figure 3). Here, CD4 is linked to type 1 diabetes mellitus.