Metformin should be held before surgery in which setting?

Metformin should be held before surgery in which setting?

• A. Normal fasting
• B. Mild fasting
• C. Severe prolonged fasting
• D. During infection

Answer: (C)

Metformin carries a risk of lactic acidosis when the body’s lactate clearance is compromised, which can happen during surgery. The perioperative period often involves potential hypoperfusion, dehydration, and renal stress from anesthesia and fluid shifts. When fasting is severe and prolonged, lactate production can rise and clearance can be further impaired, tipping the balance toward lactic acidosis. Because of this, metformin should be held in the setting of severe prolonged fasting to minimize that risk. In milder fasting or normal fasting, the risk is much lower, and while infection can also increase metabolic stress, the scenario of severe prolonged fasting presents the clearest, most significant opportunity for lactate buildup, making it the best condition to withhold metformin.

Metformin carries a risk of lactic acidosis when the body’s lactate clearance is compromised, which can happen during surgery. The perioperative period often involves potential hypoperfusion, dehydration, and renal stress from anesthesia and fluid shifts. When fasting is severe and prolonged, lactate production can rise and clearance can be further impaired, tipping the balance toward lactic acidosis. Because of this, metformin should be held in the setting of severe prolonged fasting to minimize that risk.

In milder fasting or normal fasting, the risk is much lower, and while infection can also increase metabolic stress, the scenario of severe prolonged fasting presents the clearest, most significant opportunity for lactate buildup, making it the best condition to withhold metformin.