Acute renal failure (ARF) is a serious condition which still carries a mortality of around 50%. People with diabetes may be at increased risk of developing ARF, either as a complication of diabetic ketoacidosis or hyperosmolar coma, increased incidence of cardiovascular disease, or due to increased susceptibility of the kidney to adverse effects in the presence of underlying diabetic renal disease. During the period 1956-1992, 1,661 cases of ARF have been treated at Leeds General Infirmary. Of these, we have identified 26 patients also having type 1 diabetes. ARF due to diabetic ketoacidosis is surprisingly uncommon (14 cases out of 23 patients whose notes were reviewed). All cases of ARF complicating ketoacidosis in the last decade have been associated with particularly severe illness requiring intensive care unit support, rather than otherwise 'uncomplicated' ketoacidosis. We discuss the conditions that may result in ARF in patients with diabetes and the particular difficulties that may be encountered in management.