FOXP3 and type 1 diabetes mellitus: Previous studies have shown that TGF-β plays an important role in the development of autoimmune diabetes.12, 13 TGF-β plasmid injection delays the development of diabetes in NOD mice,13 and TGF-β induces Foxp3+ T cells, restores self-tolerance and facilitates regeneration of beta-cell function in NOD mice,27 suggesting that TGF-β plays a preventive role in the development of type 1 diabetes.