The healthcare provider prescribes a regular insulin infusion for diabetic ketoacidosis at 2 units/hour. The bag contains 100 units of regular insulin in 250 mL of normal saline. How many mL per hour should be delivered?

• A. 2 mL/hour
• B. 5 mL/hour
• C. 10 mL/hour
• D. 20 mL/hour

Answer: (B)

The key idea is converting the prescribed units per hour into milliliters per hour using the insulin concentration in the bag. The bag has 100 units in 250 mL, so the concentration is 100 ÷ 250 = 0.4 units per mL. To deliver 2 units per hour, you need 2 ÷ 0.4 = 5 mL per hour. Set the infusion to 5 mL/hour to provide the prescribed 2 units each hour.