| eGFR (mL/min/1.73m²) | Metformin Recommendation |
|---|---|
| ≥ 60 | No renal dose adjustment. Monitor annually. |
| 45 – 59 | Safe to continue. Monitor every 3–6 months. |
| 30 – 44 | Reduce dose by 50%. Do not initiate new treatment. |
| < 30 | Contraindicated. Discontinue immediately. |
The major concern with Metformin in renal impairment is Metformin-Associated Lactic Acidosis (MALA). While the absolute risk is low, mortality in MALA cases is high (~50%). Risk increases significantly with acute kidney injury or severe dehydration.
9. Pharmacologic Approaches to Glycemic Treatment: Standards of Care in Diabetes—2024
Metformin-containing drugs: revised recommendations for use in patients with reduced kidney function
For eGFR between 30–60, Metformin should be withheld before IV contrast procedures and for 48 hours afterward, resuming only if renal function remains stable.