Serum anti-insulin autoantibody levels. a, Insulin autoantibodies fail to occur in transgene+ mice in the absence of native insulin 1 and insulin 2 genes. b, Mice with insulin 1 gene (insulin 1+/-, insulin 2-/-, transgene+ or transgene-) produce insulin autoantibodies (IAA). Lines connect results for individual mice. mIAA, micro-IAA assay.