At what eGFR do you consider discontinuing metformin in someone who has been on longterm therapy with well controlled DM?

At what eGFR do you consider discontinuing metformin in someone who has been on longterm therapy with well controlled DM?

• If eGFR consistently < 45 mL/min/1.73 m²
• If eGFR is/has ever been < 30 mL/min/1.73 m²
• If eGFR < 45 mL/min/1.73 m² and they need a contrasted CT scan
• As long as they are tolerating it, I continue metformin regardless of eGFR
• Other