Table 1

Summary of guideline statements on metformin use in procedures requiring intravenous contrast administration

Professional bodyMetformin advice
NICE25Should be withdrawn if serum creatinine is ⩾150 μmol/l, if the hepatic function is deranged or if any cause of tissue hypoxia is likely
ACC/AHA/SCAI26Whenever possible, metformin (especially in those with pre-existing renal dysfunction) should be withheld for 24 h before performing PCI and for 48 h afterwards*
American Diabetes Association27Discontinue for 48 h after contrast dye procedures. Contraindicated if serum creatinine is >1.5 mg/dl in men or >1.4 mg/dl women
Royal College of Radiologists28

  • If serum creatinine is normal, and a low volume of contrast agent (⩽100 ml) is to be administered intravenously, no special precaution is required

  • If serum creatinine is normal, but ⩾100 ml of contrast agent or the intra-arterial route is to be used, metformin should be withheld for 48 h after the procedure

  • If the serum creatinine is raised, the need for the contrast agent should be reassessed. If contrast injection is deemed necessary, metformin should be withheld for 48 h before and 48 h after the contrast is given and the renal function reassessed before restarting the metformin treatment

Suggested recommendationFor use of Contrast:

  • If the serum creatinine is normal, no need to withdraw

  • If the serum creatinine is raised >150 μmol/l (or 1.5 mg/dl):

    • Contrast <100 ml—no need to withdraw

    • Contrast >100 ml—withdraw for 48 h before and 48 h after the contrast is given and reassess the renal function before restarting metformin

When contrast is not used:

  • Withdraw if creatinine >150 μmol/l (or 1.5 mg/dl)

  • No need to withdraw in patients with heart failure

  • No guideline has been published from the Joint British Societies (JBS) or British Cardiovascular Intervention Society (BCIS) on metformin use in cardiac catheterisation procedures.

  • *No accompanying level of evidence category.