A nurse is caring for an adolescent client who has a long history of diabetes mellitus and is being admitted to the emergency department confused, flushed, and with an acetone odor on the breath. Diabetic ketoacidosis is suspected. The nurse should anticipate using which of the following types of insulin to treat this client?

Diabetic ketoacidosis (DKA) is an acute, life-threatening complication of diabetes characterized by hyperglycemia, ketosis, and metabolic acidosis. The clinical findings described — confusion, flushed appearance, and acetone breath — are classic manifestations. Regular insulin is the only type used to treat DKA because it has a rapid onset (within 30–60 minutes), reaches peak action quickly, and can be administered intravenously, allowing for precise titration to bring blood glucose under control rapidly. In DKA management, regular insulin is typically given as an IV infusion after initial fluid resuscitation. NPH insulin is an intermediate-acting insulin and cannot be given intravenously; it is not appropriate for acute treatment. Insulin glargine is a long-acting basal analog with no pronounced peak, designed for once-daily subcutaneous administration to control fasting glucose — it is unsuitable for acute glucose correction. Insulin detemir is similarly a long-acting basal insulin administered subcutaneously, also inappropriate for emergent DKA management. Students sometimes confuse the insulin types, but the key principle is that only regular insulin can be administered intravenously and titrated rapidly, making it the correct choice for managing the acute metabolic crisis of DKA.