Use of continuous subcutaneous insulin infusion is increasing worldwide.1 This method of insulin delivery was thought to have advantages in children, including better control of blood glucose, HbA_1c, and hypoglycaemic episodes, compared with multiple daily injections.2 3 4 5 6 7 8 A recent meta-analysis, however, showed that the benefits might not be as great as was previously hoped, particularly in younger children.9 In the UK, guidelines from the National Institute for Health and Clinical Excellence recommend continuous subcutaneous infusion when multiple dose therapy has failed in patients with HbA_1c concentrations greater than 7.5%.10

A disadvantage of using a pump is that ketoacidosis can occur quickly if a problem with insulin delivery occurs, because no background of long acting insulin is available. We describe a case of diabetic ketoacidosis caused by insulin degrading in the reservoir of a pump in sunlight and heat.