A client is ordered to receive insulin lispro (Humalog) at mealtimes. When should the nurse instruct the client to administer the medication?

Choice A rationale:

Insulin lispro is a rapid-acting insulin that begins to work within 15 minutes of injection. If administered 15 minutes after eating, it may not be able to effectively control the rise in blood glucose levels that occurs after a meal. This could lead to hyperglycemia, which can have negative short-term and long-term health consequences.

Administering insulin lispro 15 minutes after eating would delay its action and potentially lead to suboptimal blood glucose control. It's crucial to match the timing of insulin administration with the meal to ensure optimal glucose management.

Choice C rationale:

Administering insulin lispro 10 minutes after eating would also delay its action. While not as delayed as 15 minutes, it still wouldn't align with the peak of meal-related glucose absorption, potentially leading to suboptimal glucose control.

Choice D rationale:

Insulin lispro has a shorter duration of action compared to regular insulin. Administering it 30 minutes before eating could lead to hypoglycemia, a condition characterized by low blood glucose levels. Hypoglycemia can cause a variety of symptoms, including shakiness, sweating, dizziness, confusion, and even loss of consciousness.

It's essential to closely align the timing of rapid-acting insulins like insulin lispro with mealtimes to minimize the risk of hypoglycemia.

Rationale for A:

Regular insulin is the only insulin formulation that can be safely administered intravenously. It is a rapid-acting insulin that starts working within 15 minutes and peaks in 1-2 hours, making it ideal for urgent glucose control in situations like diabetic ketoacidosis.

NPH insulin is an intermediate-acting insulin that is not suitable for IV administration. It is designed to be absorbed slowly over several hours, and injecting it intravenously could lead to unpredictable and potentially dangerous fluctuations in blood glucose levels.

Subcutaneous (SQ) injection is the standard route of administration for both regular and NPH insulin outside of acute care settings. This route allows for a more gradual and consistent absorption of insulin, which is essential for maintaining stable blood glucose control.

The patient's transfer to the med/surg unit indicates that their condition has stabilized and no longer requires the aggressive glucose control that is achieved with an IV insulin infusion. Therefore, it is appropriate to transition them to SQ insulin injections.

Rationale for B:

While mixing insulins can potentially alter their absorption rates and action profiles, the primary concern with mixing NPH and regular insulin is not an increased risk of hypoglycemia. It is the incompatibility of the formulations for IV administration.

Rationale for C:

NPH and regular insulin can be mixed together for subcutaneous injection, but they are not compatible for intravenous administration.

Rationale for D:

While NPH insulin can be administered as part of an IV insulin drip in the ICU, this is typically done in specific situations where a continuous infusion of both rapid-acting and intermediate-acting insulin is required. It is not the standard practice for NPH insulin administration.