Page changed: The Truth about Oral Diabetic Drugs
Added information from updated Metformin prescribing information explaining that metformin should be discontinued at the time of or slightly before radiological procedures involving injected dye and not taken for the next 2 days. After that kidney function should be evaluated with a serum creatinine test before metformin is started again. The latter recommendation is courtesy of a radiologist who pointed me to these updated guidelines.
In rare cases in people with marginal kidney function the use of contrast dyes may cause kidney failure if a dose of metformin is taken after the dye is used. It is also possible to develop lactic acidosis when this happens. This is rare, but because many people with poorly controlled diabetes have significant kidney damage, it is important for people taking metformin to be aware of this.
These recommendations have changed from what they were a few years ago.