- Medication for treatment of type II diabetes
- Decreases hepatic glucose production and enhance glucose uptake in peripheral tissues (by increase insulin sensitivity)
- May be in a pure form or in combination with other antihyperglycemic drugs
- Renal excretion
- Most significant reaction is lactic acidosis, which has a high mortality (up to 50%)
- Most metformin associated lactic acidosis (MALA) occured in patients with coexisting renal dysfunction (high level of metformin due to poor excretion)
- The use of iodinated contrast agents in patients with pre-existing renal dysfunction can lead to significant contrast-induced nephropathy - that could, in turn, worsen MALA.
- Patients with pre-existing renal dysfunction
- Patients with comorbidities that could give rise to lactic acidosis (liver dysfunction, alcohol abuse, heart failure, myocardial ischemia, peripheral muscle ischemia, sepsis, severe infection)
- Patients with normal renal function and no known comorbidities -> no need to discontinue metformin prior to IV contrast administration
- Patients with known comorbidities -> Discontinue metformin at time of IV contrast administration, and withheld for 48 hours
- Patients with known renal dysfunction -> suspend metformin at time of IV contrast administration, renal function follow-ups until safe reinstitution of metformin can be assured
American College of Radiology. Manual on Contrast Media version 6 (2008).
McCartney MM, et al. Metformin and contrast media - a dangerous combination? Clin Radiol 1999;54:29.