In type1 diabetes, the islets become infiltrated by immune cells in a process known as "insulitis". This has been well studied in animal models of diabetes but is much less understood in humans. In fact, since the beginning of the last century, fewer than 200 cases of human insulitis have been studied. We are fortunate in having access to a large cohort of appropriate pancreas samples in which to study insulitis and our team has been characterising the process. We have discovered that at least two different profiles of insulitis exist in humans. We are now building on this foundation to understand exactly how insulitis develops and what role it plays in causing beta-cell death. This should then provide a means to target the process selectively in individual patients.