T-cell insulitis found in anti-GAD65+ diabetes with residual beta-cell function. A case report.

CASE HISTORY: We recently encountered a 65-year-old anti-GAD+ diabetic woman with residual beta-cell function who was proved to have T-cell insulitis. The proportion of CD4+ and CD8+ cells varied among individual islets, although CD4+ cells tended to be the predominant T-cell type in the islets examined. All of the islets examined still contained insulin, suggesting that beta-cell mass may have been preserved. DISCUSSION: It is well known that lymphocytic infiltration of pancreatic islets, a condition referred to as "insulitis," is seen in acute-onset type 1 diabetes at autopsy and in biopsy specimens. However, there have been no proven cases of insulitis in type 1 diabetes with residual beta-cell function. We believe that this is the first type 1 diabetic patient with residual beta-cell function who was proven to have T-cell insulitis. This novel evidence will contribute to the proper classification and treatment of diabetes and to a better understanding of the pathophysiology of type 1 diabetes.