CD4 and type 1 diabetes mellitus: Of note, at 13 weeks of age (when the NOD mice start to develop into T1D form insulitis phase gradually), the percentage of Foxp3+ in CD4+ T cells of NOD-CB mice markedly decrease to 6.43% (p < 0.001), while the percentage of NOD controls still held at 9.48% (Figure 5E).