Islet autoantibodies are not thought to cause direct damage to the beta cells, and in mouse models anti-islet antibodies alone do not precipitate diabetes.11 However, in mouse models, autoantibodies have been shown to enhance accumulation of islet-reactive CD4+ T cells and promote diabetes among mice who already have an increased frequency of islet-reactive CD4+ T cells.11 Yet, the detection of islet autoantibodies in serum is currently the most reliable diagnostic test for type 1a (autoimmune) diabetes in subjects with hyperglycemia. This evidence concerns the gene CD4 and diabetes mellitus.