Despite the rapid development of overt diabetes, the number of splenic, PLN, and pancreas-infiltrating CD4+ T cells was reduced in BDC.Foxo1–/– mice approximately 10-fold compared with BDC.Foxo1+/+ mice, which is consistent with reduced peripheral T cell numbers in Foxo1-deficent mice (Supplemental Figure 4, E–G) (29). Here, CD4 is linked to diabetes mellitus.