High frequency of autoantibodies in patients with long duration type 1 diabetes

Excerpt

To the Editor: It is apparent that small numbers of beta cells are able to survive in the type 1 diabetic pancreas for many years after clinical onset. Thus, insulin-positive islets have been observed in pancreases of patients with long-standing type 1 diabetes, with islets showing evidence of beta cell proliferation, apoptosis and T cell infiltration [1]. Circulating C-peptide was evident in the majority of Joslin Medalists who survived more than 50 years of diabetes, with age at disease onset and HLA genotype affecting the concentrations detected [2]. Post-mortem examination of pancreases from nine of these patients demonstrated residual beta cells in all individuals, with beta cell proliferation and T cell infiltration still being evident, even in those with undetectable serum C-peptide [2]. Although signs of regeneration are not always seen in the diabetic pancreas, these observations suggest that beta cell turnover may occur long after diagnosis of type 1 diabetes, surviving beta cell mass being determined by relative rates of beta cell renewal and autoimmune beta cell destruction. Factors influencing persistence of autoimmunity in long-duration type 1 diabetes have not been widely investigated. In this study we determined the frequencies and levels of antibodies to the diabetes-associated islet autoantigens GAD (GADA), IA-2 (IA-2A) and zinc transporter-8 (ZnT8A) in patients with long-duration type 1 diabetes, and investigated the influence of age at diagnosis and HLA genotype on autoantibody persistence. …