Prevalence of diabetes-specific autoantibodies in patients at risk for adult onset diabetes mellitus.

To evaluate the potential of autoimmune markers in identifying patients with slowly progressive IDDM in the prediabetic state, we screened a population of 151 patients aged 37-70 years with impaired glucose tolerance (IGT) for the presence of islet cell antibodies (ICA), insulin autoantibodies (IAA), antibodies to glutamic acid decarboxylase (GADA), and antibodies to tyrosine phosphatase IA-2 (IA-2A). Autoantibodies were found in 5 (3.3%) patients with IGT suggesting the presence of an autoimmune-mediated beta cell destruction. All of them were positive for high level ICA (> 20 JDF-U) and 1 ICA positive subject had additional GADA (100 GADA-U). In contrast, none of the subjects had IA-2A or IAA. We here demonstrate a low prevalence of autoimmune diabetes among middle-aged subjects with IGT. ICA and GADA but not IA-2A or IAA may represent autoimmune markers for slowly progressive IDDM before the manifestation of the disease.