•Metformin puts a patient at increased risk of renal failure when combined with a contrast medium. Metformin should be withheld 48 hours before and after all procedures.
•Lactic acidosis is also a potential effect of metformin overdose because lactate uptake by the liver is diminished.
•Metformin rarely causes hypoglycemia because it does not stimulate insulin release, it decreases glucose production in the liver and glucose absorption in the GI tract. It also improves insulin sensitivity.
•Metformin does not cause hyperglycemia or arrhythmias.