Given that both sexes of NOD mice lacking Vγ1+ cells had a reduced incidence of diabetes, our discovery of relatively large numbers of IFNγ-biased Vγ1+ cells in normal NOD mice suggests that these cells intensify the inflammation, and thereby exacerbate on-going autoaggressive attack on the pancreatic islets and the eventual development of diabetes. This evidence concerns the gene IFNG and diabetes mellitus.