Metformin Associated High Anion Gap Metabolic Acidosis: A Case Report

Abstract

Metformin, a hypoglycemic agent, has been widely used to treat patients with type 2 diabetes mellitus; however, it might be related to a fatal complication: lactic acidosis. Risk factors include old age, renal function impairment, and any condition associated with tissue hypoxia, such as sepsis and myocardial infarction. Here we present a case with severe metabolic acidosis due to metformin intoxication. The 72-year-old male patient felt drowsy at home. Clinical presentations included hypoglycemia, hypotension, hypothermia, bradycardia, acute renal deterioration, and respiratory failure. Laboratory data revealed high anion gap metabolic acidosis (46.5 mEq/L) which was intractable with high doses of sodium bicarbonate. After reviewing the patient's history, we found large doses of metformin were prescribed for diabetes mellitus. Emergent hemodialysis was arranged after other possibilities were excluded and the symptoms recovered rapidly. Physicians should be familiar with clinical symptoms of metformin intoxication. Morbidity and death due to metformin intoxication include acute renal failure, electrolyte disturbance, arrhythmia and cardiovascular suppression. The role of sodium bicarbonate in the treatment is limited. Hemodialysis is the treatment of choice and should be urgently initiated.