Destruction of islets of Langerhans in Type I diabetes

A photomicrograph of a section through the pancreas of a patient in the acute phase of Type I (early onset) diabetes. Nuclei are stained blue. The islet beta-cells have been immunolabelled for insulin (brown). The islet has been invaded by lymphocytes (small cells with large, dense nuclei) which attack and destroy the insulin-producing cells. Even though some insulin is produced this is not enough to sustain normal function.