Increased circulating levels of IL-17A (11) and mRNA expression of IL-17A have been observed in circulating memory CD4+ T cells from children with new-onset T1D (12); furthermore, local IL-17 production has been detected in pancreatic islets around the time of disease onset (13) and human β-cells were shown to be susceptible to IL-17A–induced apoptosis (12). This evidence concerns the gene CD4 and type 1 diabetes mellitus.