Metformin and serious adverse effects

In reply: Chong’s letter highlights some important issues, and his points are well made. As we imply in our editorial,1 the evidence base on which to base guidelines and decisions is poor, which is one of the reasons that the guidelines differ widely between countries and organisations. Specialty-specific guidelines must also take into account practicalities. We elected to follow the more conservative end of the guideline spectrum in our suggestions, accepting that, in many circumstances, these would be difficult or impossible to follow. From a radiological perspective, it would require a significant change in practice to implement guidelines such as those we suggested, and the evidence base supporting such a change does not exist.

Metformin is a short-acting drug and stopping it at the time of a potentially hazardous procedure will almost always be effective in preventing drug-related complications. Overall, the aim of our article was to raise awareness of the potential hazards of metformin use, and to encourage practitioners to follow available and relevant guidelines.