A source of glucose is the most important thing for parents of a 3-year-old with type 1 diabetes mellitus to carry. If the child receives insulin based on the expected intake and exertion but either eats less or exercises more than anticipated, life-threatening hypoglycemia may occur. Administration of insulin or blood glucose testing is less emergent (though very important, of course) than glucose in the setting of profound hypoglycemia. Bottled water is less necessary, although important.