On the morning of surgery, which adjustment should be made to fast-acting insulin?

• A. Hold fast-acting insulin
• B. Continue full dose of fast-acting insulin
• C. Increase fast-acting insulin by 1/2 dose
• D. Skip all insulin in the morning

Answer: (A)

When a patient is going to have surgery and will be fasting, the fast-acting (rapid-acting) insulin is held because there’s no carbohydrate intake to cover and the risk of hypoglycemia during anesthesia is real. Rapid-acting insulin peaks shortly after dosing and is meant to match meal intake; without a meal, continuing it can push blood glucose too low once the patient is under anesthesia and unable to respond to symptoms. Intraoperative glucose management typically relies on IV insulin infusion with dextrose to keep levels in a safe range, rather than giving a preoperative rapid-acting dose. Holding the fast-acting insulin avoids unnecessary hypoglycemia, whereas continuing it, increasing it, or skipping all insulin could respectively increase hypoglycemia risk or worsen hyperglycemia.