For how long does metformin have to be withdrawn in a patient with diabetes who develops acute kidney injury?
Jürgen Floege, MD: This is obviously the concern for lactic acidosis. It used to be that you should not give it below a glomerular filtration rate (GFR) of 60 mL/min/1.73 m2; this has gone down to 30 mL/min/1.73 m2 now. It is a little bit similar as with radiocontrast [see Contrast-induced AKI: Is it real?]. We are very concerned about a complication that is very rare. Yes, lactic acidosis does exist, but it is very, very rare.
As a rule of thumb, I try to avoid [metformin] if my GFR is below 30 mL/min/1.73 m2, or vice versa: if my GFR increases above 30, then I can restart it.