Metformin and serious adverse effects

To the Editor: I refer to the recent editorial on “Metformin and serious adverse effects”.1

I would like to highlight the position of the Royal Australian and New Zealand College of Radiologists (RANZCR) on the use of metformin hydrochloride when administering intravascular contrast media. The RANZCR has adopted an evidence-based approach in formulating its guidelines. The College guidelines on metformin hydrochloride and intravascular contrast media are available at <www.ranzcr.edu.au/open/policies/diagnostic_imaging/pol1_2.htm>.

The current guideline is that there is no need for patients to stop taking metformin hydrochloride for 24–48 hours before administration of an intravascular contrast medium. Stopping or continuing to take metformin depends on the patient’s renal status, and the likelihood of inducing renal dysfunction when intravascular contrast is administered. If discontinuation is required, then the drug only needs to be stopped for 48 hours, commencing on the day of administration of intravascular contrast.