In a single case of patient who died 5 days after T1D diagnosis, increased mRNA expression of IL-17A, RORC, and IL-22 along with IFN-γ was detected [24] suggesting the direct involvement of IL-17 in destruction of β cells and this notion is supported by in vitro data where IL-17 has direct toxicity to human β cells. Here, IL17A is linked to type 1 diabetes mellitus.