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NCLEX-RN Insulin practice questions

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These are original practice items written to the NCLEX-RN blueprint (4 options, no penalty for wrong answers), not actual exam questions. Try each one before you open the answer.

What this topic covers

Insulin sits inside the Pharmacological and Parenteral Therapies category of the NCLEX-RN. Our bank holds 49 verified items tagged to it, and the 4 below are a fixed sample so the page stays the same every time you open it. Each one shows the reasoning, not just the letter.

The topic tag comes from our own items rather than from a published syllabus, so treat it as a map of what we cover. For the official category breakdown see the NCLEX-RN page.

Insulin sample questions

Question 1

A 58-year-old client with type 1 diabetes mellitus is admitted with nausea, vomiting, and abdominal pain. Blood glucose is 420 mg/dL, serum potassium is 5.8 mEq/L, and arterial pH is 7.18. The nurse administers intravenous fluids and an insulin drip as prescribed. Which laboratory value requires the nurse's immediate reassessment after starting the insulin infusion?

  1. A Serum potassium level
  2. B White blood cell count
  3. C Hemoglobin A1c level
  4. D Serum creatinine level
Show the answer and explanation

Correct answer: A

Insulin drives potassium into the cells, so the initial hyperkalemia of diabetic ketoacidosis can quickly turn into hypokalemia once the insulin infusion starts. Close potassium monitoring is essential to prevent life-threatening dysrhythmias and to guide potassium replacement.

Why the other options are wrong:
B: The white blood cell count may be elevated from stress or infection, but it is not changed by the insulin infusion.
C: Hemoglobin A1c reflects average glucose over about 3 months and has no role in acute DKA management.
D: Creatinine reflects kidney function and should be monitored, but it does not shift rapidly with insulin the way potassium does.

Question 2

A 34-year-old female client with type 1 diabetes mellitus is admitted with diabetic ketoacidosis. The nurse initiates an intravenous insulin infusion at 0.1 units/kg/hr per protocol. The client's blood glucose is 520 mg/dL. One hour later, the blood glucose is 490 mg/dL. Which action should the nurse take?

  1. A Increase the insulin infusion to 0.14 units/kg/hr and recheck the blood glucose in 1 hour.
  2. B Continue the current infusion rate and monitor the blood glucose level every 2 hours.
  3. C Administer a 10-unit intravenous bolus of regular insulin and continue the current infusion.
  4. D Decrease the insulin infusion to 0.05 units/kg/hr to prevent hypoglycemia and recheck in 2 hours.
Show the answer and explanation

Correct answer: A

In DKA, glucose should fall about 50 to 75 mg/dL per hour. A drop of only 30 mg/dL in the first hour is inadequate, so the infusion is titrated upward per protocol and glucose is rechecked hourly.

Why the other options are wrong:
B: Keeping the same rate ignores an inadequate response, and checks every 2 hours are too infrequent during an insulin infusion.
C: A fixed 10-unit bolus is not weight-based and is not the protocol's titration step; it would need a separate prescription.
D: Decreasing the rate would slow glucose and ketone correction further when the response is already too slow.

Question 3

A 60-year-old male in the medical-surgical unit with type 2 diabetes mellitus is receiving insulin glargine 30 units subcutaneously at bedtime. At 0600, the nurse obtains a fingerstick glucose of 185 mg/dL. The sliding scale order is: for glucose 151-200 mg/dL, give 3 units of insulin aspart subcutaneously. Which action should the nurse take?

  1. A Give 30 units of insulin aspart subcutaneously now and discontinue the glargine
  2. B Administer 3 units of insulin aspart subcutaneously and hold the next glargine dose
  3. C Administer 3 units of insulin aspart subcutaneously now and continue the glargine at bedtime
  4. D Hold the insulin aspart and increase the glargine dose to 35 units tonight
Show the answer and explanation

Correct answer: C

The glucose of 185 mg/dL falls in the 151 to 200 mg/dL range, so 3 units of insulin aspart are given as prescribed. Glargine provides basal coverage and continues as ordered; it is not changed because of a single reading.

Why the other options are wrong:
A: Thirty units is ten times the prescribed correction dose and could cause severe hypoglycemia, and glargine should not be stopped.
B: Holding glargine removes basal insulin and leads to hyperglycemia.
D: Holding the correction dose leaves the hyperglycemia untreated, and nurses cannot change the glargine dose.

Question 4

A nurse is caring for a 38-year-old client with type 1 diabetes mellitus who is receiving a continuous intravenous infusion of regular insulin at 5 units/hr for diabetic ketoacidosis. The client's current blood glucose is 280 mg/dL, down from 520 mg/dL four hours ago. The nurse notes that the client's serum potassium level is 3.0 mEq/L. Which action should the nurse take first?

  1. A Administer 20 mEq of potassium chloride intravenously over 1 hour.
  2. B Decrease the insulin infusion to 3 units/hr to prevent hypoglycemia.
  3. C Increase the insulin infusion to 7 units/hr to achieve faster glucose correction.
  4. D Switch to subcutaneous insulin glargine 10 units now and stop the infusion.
Show the answer and explanation

Correct answer: A

A potassium of 3.0 mEq/L during DKA treatment is dangerously low and can cause dysrhythmias, because insulin keeps shifting potassium into the cells. IV potassium replacement is the priority, and DKA protocols often pause insulin until potassium recovers.

Why the other options are wrong:
B: Glucose is falling at an appropriate rate and is not near hypoglycemia, and lowering insulin does not treat the hypokalemia.
C: More insulin would drive more potassium into the cells and worsen hypokalemia.
D: Subcutaneous insulin replaces the drip only after DKA resolves; stopping the infusion now is premature.

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