The frequency of diabetic ketoacidosis and hypoglycemic coma in a large series of patients with insulin-dependent diabetes treated by long-term continuous subcutaneous insulin infusion was compared with the frequency of these events in a matched group of patients treated by conventional insulin injections at the same hospital over the same period of time. Ketoacidosis and hypoglycemic coma occurred no more frequently in continuous subcutaneous insulin infusion-treated patients. Therefore, intensified insulin therapy achieved by continuous subcutaneous insulin infusion does not appear to be associated with a greater risk of ketoacidosis or hypoglycemic coma than does conventional insulin therapy.