IL17A and type 1 diabetes mellitus: Mainly T helper type (TH) 1 cells, producing the key cytokines IFN-γ and TNF-α, were detected in T1D-specific pancreas islet inflammation (1), but also other CD4+ T-cell subsets, e.g., producing IL-17 or IL-21, have been found at higher frequencies in peripheral blood from patients with T1D (2, 3).