Lactic acidosis is the most severe adverse effect associated with metformin therapy of type 2 diabetes mellitus. The risk increases in patients with impaired renal function, most commonly due to diabetic nephropathy, and may be augmented when concurrent medication with a negative impact on renal function is used.
The authors present a series of three patients who were admitted to a department of infectious diseases for acute gastroenteritis and within a few hours developed shock syndrome caused by severe lactic acidosis due to accumulation of metformin.