Severe Lactic Acidosis in a Patient with Type 2 Diabetes Mellitus on Metformin

Introduction: Metformin-associated lactic acidosis (MALA) is a complication of altered lactate and hydrogen metabolism leading to life-threatening lactic acidosis in the setting of Metformin use or overdose. The major risk factors for developing MALA include poor renal function, impaired hepatic metabolism, and diseases that can cause increased production of lactate. Case Description: A 67-year-old female with type 2 diabetes mellitus on Metformin and chronic kidney disease (baseline creatinine: 1.4) presented to a local ER with nausea, vomiting, diarrhea, and abdominal pain for three days. She was found to have severe lactate metabolic acidosis (pH: 6.84, bicarbonate: 8, lactate: 11.6) without hemodynamic instability. The patient underwent emergent hemodialysis for severe acidosis and hyperkalemia (K: 8.2) in the setting of acute kidney injury (serum creatinine: 7.47, BUN: 56). She was transferred to our hospital with persistent metabolic acidosis (pH: 6.97, bicarbonate: 7, lactate: 17) despite 4 hours of hemodialysis at the local hospital. On arrival to the ICU, the patient remained hemodynamically stable. CRRT was initiated urgently and lasted about 48 hours. Her lactic acidosis resolved, and the patient was discharged 8 days later with serum Cr 2.19. At 2-week follow up at renal clinic, her kidney function improved with creatinine back to baseline (1.4). Discussion: Metformin is widely used to treat type 2 diabetes mellitus, and is generally considered a safe drug. However, patients with preexisting chronic kidney disease are at increased risk of developing a potentially fatal lactic acidosis. This case demonstrated the importance of early recognition and treatment of MALA as evidenced in this patient with known history of Metformin use and severe lactic acidosis. Hemodialysis continues to be the definitive treatment of MALA and should be initiated in any patient with severe acidosis.