Lactic acidosis is a rare, but serious, metabolic complication that can occur due to metformin accumulation during treatment with Metformin when it occurs. It is fatal in approximately 50% of cases. Lactic acidosis may also occur in association with a number of pathophysiologic conditions, including diabetes mellitus, and whenever there is significant tissue hypoperfusion and hypoxemia. Lactic acidosis is characterized by elevated blood lactate levels, decreased blood pH, electrolyte disturbances with an increase anion gap, and an increased lactate/pyruvate ratio.