Metformin-Associated Lactic Acidosis: A Case Report and Review

Metformin is widely prescribed as the first-line medication for type II diabetes mellitus. While the gastrointestinal side effects of metformin such as nausea, vomiting, diarrhea, and heartburn are quite common, one dangerous side effect of metformin, lactic acidosis, is extensively discussed yet rarely reported. Here, we discuss a 53-year-old female with type II diabetes mellitus who presented to an emergency department (ED) with chief complaints of dizziness and lightheadedness. The patient had chronic kidney disease (CKD) with a baseline estimated glomerular filtration rate (eGFR) of 45 mL/minute/1.73 m². Initial laboratory results showed acute kidney injury (AKI) with hyperkalemia and lactic acidosis of 20 mmol/L. The patient was admitted to the ICU requiring emergent dialysis. Later, she was diagnosed with metformin-associated lactic acidosis (MALA). Her AKI and lactic acidosis subsequently improved. Metformin-associated lactic acidosis (MALA) is a rare but serious side effect of metformin. It is primarily reported in patients with chronic renal failure; therefore, it should be used with caution in these patients. Renal replacement therapy (RRT) is the critical management option for patients with MALA. Because of this, physicians prescribing metformin should carefully monitor all patients and assess the risk of developing severe side effects.