A patient with type 1 diabetes reports mixing NPH and regular insulin to allow for one injection. The nurse knows:

Choice A reason: NPH insulin is not mixed with insulin glargine, as glargine’s pH and formulation cause precipitation or altered pharmacokinetics when combined. NPH can be mixed with regular insulin, as they are compatible, making this choice incorrect for the patient’s reported practice. Choice B reason: NPH and regular insulin are compatible and routinely mixed in one syringe to provide both intermediate and short-acting coverage. They don’t react chemically or lose efficacy when combined properly, making this choice incorrect, as mixing is a standard practice in diabetes management. Choice C reason: Mixing NPH and regular insulin does not increase potency; it combines their pharmacokinetics for basal and prandial glucose control. The mixture delivers the additive effects of each insulin’s profile without enhancing overall potency, making this choice inaccurate for their combined action. Choice D reason: Mixing NPH (intermediate-acting) and regular insulin (short-acting) is an accepted practice to manage type 1 diabetes with one injection, covering basal and prandial needs. Proper technique (drawing regular insulin first) ensures stability, making this the correct choice for the patient’s reported insulin administration.