Diabetic ketoacidosis (DKA) and hyperglycaemic hyperosmolar state (HHS) are the major hyperglycaemic crises associated with diabetes mellitus. The patients admitted to hospital with DKA has remained unchanged over the past 10 years with 7700 admissions in 1998-1999 and 8400 admissions in 2004-2005 in England alone. The common precipitating factor for hyperglycaemia crisis is infection, including pneumonia, urinary tract infection and sepsis. Diabetic ketoacidosis occurs frequently in younger patients with type 1 diabetes mellitus, but 13% of cases in the USA are patients over the age of 60 years and a small proportion of patients have type 2 diabetes mellitus. Resuscitation begins with an isotonic, sodium based fluid. Usually this is sodium chloride 0.9% but may be a sodium containing colloid if the patient is in shock. The rate of administration is dependent on the nature of the hyperglycaemic crisis, and guidance is given in the algorithms for management.