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?

Choice A rationale Regular insulin is a short-acting insulin that is the only formulation approved for intravenous administration and is the standard treatment for diabetic ketoacidosis (DKA). Its quick onset, typically within 30 minutes when administered subcutaneously, and its predictable action profile allow for precise, rapid titration via an intravenous infusion to lower blood glucose and suppress ketone body production during a metabolic emergency like DKA. Choice B rationale Insulin detemir is a long-acting basal insulin analog with a slow onset and prolonged duration of action, typically 12 to 24 hours, making it unsuitable for the acute management of hyperglycemia and ketosis in DKA. It is designed to provide steady, background insulin levels for day-to-day management and is not used for the rapid, emergent correction needed in DKA. Choice C rationale Insulin glargine is another long-acting basal insulin analog that provides a relatively peakless level of insulin over 24 hours, which is ideal for maintaining basal glycemic control. However, its delayed onset and lack of a significant peak effect make it ineffective and inappropriate for the urgent intravenous infusion required to reverse the critical metabolic derangements of DKA. Choice D rationale NPH insulin is an intermediate-acting insulin with an onset of 1 to 4 hours and a peak action in 6 to 10 hours. While used for basal and meal coverage, its delayed and variable absorption profile makes it too slow and unpredictable for the immediate, minute-by-minute titration needed for the aggressive management of severe hyperglycemia and acidosis in a DKA crisis.