-Diabetic ketoacidosis and hyperosmolar hyperglycaemic syndrome are important hyperglycaemic emergencies seen in patients with diabetes. Occasionally, differentiation between the two conditions can be difficult. We present the case of a patient whose hyperglycaemic emergency was managed in a way that could have adversely influenced the outcome. We also discuss important aspects of the new Joint British Diabetes Societies Guidelines on the management of hyperglycaemic emergencies.