For the past 25 years, efforts have been made to stop progression of type 1 diabetes by immunotherapeutic strategies targeting autoimmune mechanism(s) involved in the disease. In the mid-1980s, chemical immunosuppression with ciclosporin proved a successful intervention in advanced disease, once hyperglycaemia had been established. As expected, however, the effect persisted only during drug administration, which implied a requirement for chronic treatment that would be incompatible with the prerequisites of safety in type 1 diabetes—a disease that preferentially affects children and young adults.