Diabetic ketoacidosis is the principal cause of hospital admissions for diabetic patients under 20 years of age, and accounts for at least 4000 deaths per annum in the United States. Current mortality rates differ widely throughout the United States, ranging from 0-19 per cent, with an average of 10 per cent. The principal reason for this wide range in the percentage of mortality are the differing criteria for diagnosis and attributing deaths to diabetic ketoacidosis. There are many reported precipitating causes of diabetic ketoacidosis which may be reduced to four common pathways: insulin deficiency, stress hormone excess, dehydration and fasting. Infection is the most common precipitating cause in most reported series of diabetic ketoacidosis, but stress in any form can lead to metabolic decompensation. Omission of insulin is an unusual cause of ketoacidosis, and in approximately one-quarter of patients no cause can be identified. Each of the four common pathways through which these precipitating causes induce diabetic ketoacidosis results in a rise in ketone body and glucose production and/or concentration. Prevention of diabetic ketoacidosis has been underemphasized in the care of the ill diabetic patient. Prevention of metabolic decompensation in the stressed diabetic patient requires a knowledgeable physician and a cooperative patient. Appropriate physician management of insulin and suppression of stress hormones should prevent diabetic ketoacidosis in all patients who can ingest fluid. Recent studies suggest that if the mortality rate from diabetic ketoacidosis is to be significantly reduced, prevention of this complication is mandatory. Appropriate treatment of diabetic ketoacidosis is not difficult if the physician maintains an accurate flow chart and provides sufficient insulin, rehydration and potassium. We favour the use of low-dose insulin therapy, rehydration with isotonic saline, and aggressive potassium replacement. The administration of sodium bicarbonate is controversial and should be restricted to patients with an arterial pH of less than 7.0 and/or a patient in cardiogenic shock. The majority of complications encountered during the treatment of diabetic ketoacidosis are avoidable if proper care and attention is provided by the physician.