Extrapolating the discovery of IL-2 as a novel autoantigen in mouse models of T1D to humans, we found that a significantly higher fraction of T1D patient sera (from three independent cohorts) contain anti-rhIL-2 autoantibodies than either healthy donors or type 2 diabetic patients (who present chronic hyperglycaemia in the absence of islet autoimmunity) (Fig. 4a and Supplementary Tables 2 and 3). This evidence concerns the gene IL2 and type 1 diabetes mellitus.