Metformin and iodinated contrast

What it is

Metformin is the first line treatment for type 2 diabetes. It is not nephrotoxic in itself, but it is secreted by the kidney; so where the kidney cannot clear it, it accumulates in the blood causing lactic acidosis. That one line stands behind every rule below.

How it is treated

Hold metformin for 24 hours before procedures using contrast dye.

The renal rule beside it is written by eGFR. Where there is nephropathy with eGFR of 30 or less, metformin has to be stopped. At GFR 30 to 40, modify the dose, or, if the patient is not on metformin, do not start giving it.

Apart from the kidney, it should be taken after food to minimize GI upset.