KIR3DL1 and type 1 diabetes mellitus: Although >40 genetic loci are implicated in type 1 diabetes susceptibility, genes encoding the human leukocyte antigens (HLA) are the strongest genetic contributors.1 Killer cell immunoglobulin-like receptors (KIR) are found on the surface and regulate the function of Natural Killer (NK) cells, CD8+ and CD4+ αβ T cells as well as γδ T cells.2 Inhibitory KIR (KIR2DL and KIR3DL groups) have immunoreceptor tyrosine-based motifs within their long cytoplasmic tail.