40 adults with type 1 diabetes received one injection of IL-2 SC in different dosing cohorts (0.04×106 to 1.5×106 IU/m2) and followed up for 7 days. The end point was the maximum percentage increase in Tregs (CD3+CD4+CD25highCD127low) from baseline frequency. This evidence concerns the gene CD4 and type 1 diabetes mellitus.