A nurse is teaching a client who has a new prescription for regular insulin and NPH insulin. Which of the following instructions should the nurse include in the teaching?

A. Inject the insulin into a large muscle: Insulin should always be injected subcutaneously, not into a large muscle. The recommended areas for injection are the abdomen, thighs, or upper arms, where there is sufficient subcutaneous fat. B. Aspirate the medication prior to administration: Aspirating the syringe before injecting insulin is no longer necessary. It is not recommended for insulin injections, as it does not prevent complications and adds unnecessary discomfort for the patient. C. Keep the open vial of insulin at room temperature: Once opened, insulin can be stored at room temperature for up to 28 days. Storing it at room temperature helps prevent discomfort during injection, as cold insulin can be painful. D. Administer the insulin in two separate injections: Regular and NPH insulin can be mixed in the same syringe as long as proper technique is followed—drawing up the regular (clear) insulin before the NPH (cloudy) insulin.