Rodent versus human insulitis: why the huge disconnect?

The purpose of this article is to summarize recent developments in the histopathology of recent-onset type 1 diabetes. Insulitis is considered to be the defining lesion in young type 1 diabetic patients, and insight into its pathogenic mechanism is crucial for the development of effective new therapies. The present overview highlights some recent developments including an international consensus guideline for the diagnosis of insulitis in type 1 diabetic patients, immunophenotyping of the insulitic lesions, evidence for a heterogeneity of the disease process and a discussion on the differences and similarities between insulitis in patients and in rodent models of the disease. We have reviewed recent data, published over the last year, on the nature and mechanism of insulitis in both patients and the nonobese diabetic mouse model.