A 58-year-old man with type 2 diabetes has eGFR 38 mL/min/1.73m². His HbA1c is 8.4%. Which antidiabetic agent should be AVOIDED due to risk of lactic acidosis at this level of renal function?
- A Metformin ✓
- B Sitagliptin (dose-adjusted)
- C Empagliflozin
- D Insulin glargine
Correct answer: A. Metformin
Explanation
Metformin is contraindicated when eGFR falls below 30 mL/min/1.73m² and should be used with caution (reduced dose) when eGFR is 30–45; many guidelines recommend stopping it at eGFR < 45 in high-risk patients due to risk of lactic acidosis from decreased renal clearance of the drug. Sitagliptin can be dose-adjusted to 25 mg/day at eGFR 15–30. SGLT-2 inhibitors like empagliflozin are generally avoided below eGFR 20–30 for glycaemic efficacy but are used for cardiorenal protection at eGFR ≥ 20. Insulin has no renal contraindication though doses may need adjustment.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.