The conditions experienced by people in custody in the UK have received considerable attention recently and there has been considerable debate concerning the standards of healthcare in British prisons. The Prison Health Care Service works under great pressure and difficulties and doctors have to deal with a large and ever-changing population, often with mental and physical disorders, who are frequently manipulative. This article highlights problems encountered in delivering diabetes care in prisons. Prisoners may self-induce diabetic ketoacidosis by refusing insulin injections, in order to be transferred to an outside hospital. On the other hand, prison staff may mis-interpret the symptoms of poorly controlled diabetes as 'acting up' by prisoners and inappropriate treatment can be given. If structured diabetes care is provided in prison, however, with close liaison between the Prison Staff and the local Diabetes Care Team, the basics of modern diabetes management can be provided. Good diabetic metabolic control can be achieved in the majority of patients, probably due to the rigid dietary regime, no alcohol and compliance with treatment. Imprisonment can ensure screening for diabetic complications and reassessment of treatment regimens. The British Diabetic Association guidelines for the provision of diabetes care in British prisons are outlined in this article.