Unusual Case of Metformin-Associated Lactic Acidosis in Patient with Type 2 Diabetes Mellitus.

BACKGROUND Metformin is recommended as the first-line therapy for type 2 diabetes mellitus, according to the American Diabetes Association. It is considered a safe medication with minimal adverse effects, with the most common being gastrointestinal. Metformin-associated lactic acidosis (MALA) is a rare but life-threatening complication. MALA usually occurs in patients with kidney dysfunction. However, it can still occur with preserved kidney function with the ingestion of a large dose of metformin. CASE REPORT A 66-year-old man with a significant medical history of type 2 diabetes mellitus presented after an intentional ingestion of a high dose of metformin (3000 mg/day). He was admitted to our hospital with symptoms of fatigue, nausea, vomiting, abdominal pain, and watery diarrhea lasting for 3 days. His initial laboratory findings were remarkable, with a serum creatinine level of 819 µmol/L. Arterial blood gas revealed severe lactic acidosis, with a pH of 6.94, HCO₃⁻- of 3 mEq/L, anion gap of 48 mmol/L, and lactate level of 15 mmol/L. Emergent continuous renal replacement therapy was done. Two days later, his condition improved considerably, and the lactic acidosis was resolved entirely. He was discharged on day 11 of hospitalization. CONCLUSIONS MALA is rare but life-threatening complication of treatment with metformin. MALA should be considered when there is evidence of metformin ingestion and renal insufficiency in patients with lactic acidosis. The curative treatment of MALA is based on hemodialysis, but the main remedy is prevention, which requires patient compliance with taking metformin as prescribed.