Type 1 diabetes (T1D) is an autoimmune disease in which the pancreas makes little or no insulin. The details on the events that occur during autoimmune destruction of the pancreatic beta-cells have been studied extensively yet the mystery of what causes autoimmunity is unknown. In a new study, researchers present a testable hypothesis to explain the initiation of autoimmunity. If validated, this would allow early detection and possible prevention of T1D in susceptible individuals.