Metformin-Associated Lactic Acidosis: A Case Report

Metformin is a widely prescribed and effective oral antidiabetic agent used in the treatment of type 2 diabetes mellitus (DM). Although generally well tolerated, metformin-associated lactic acidosis (MALA) is a rare but potentially fatal complication, especially in the presence of predisposing risk factors. Herein, we present a case of MALA that developed after volume depletion related to bowel preparation for endoscopic procedures. A 56-year-old male patient with type 2 diabetes mellitus who was taking metformin presented with nausea, vomiting, and decreased urine output following endoscopy preparation. Laboratory tests revealed severe metabolic acidosis (pH: 7.05; HCO₃⁻: 8.9 mmol/L; lactate: 21 mmol/L) and severe renal dysfunction (creatinine: 11.91 mg/dL). The patient was diagnosed with MALA based on clinical and biochemical findings and underwent emergency hemodialysis and intensive intravenous hydration. After treatment, the patient's metabolic parameters improved rapidly and the need for dialysis disappeared. Outpatient follow-up revealed that renal function had returned to normal. This case underscores the potential risk of continuing metformin therapy during peri-procedural periods associated with volume depletion. The omission of pre-procedural discontinuation of metformin in our patient likely contributed to the development of life-threatening lactic acidosis. Early diagnosis and timely initiation of renal replacement therapy are critical for reducing mortality in MALA cases.