Fatal metformin-associated lactic acidosis in a healthy woman after massive overdose

12 mmol/L, lactate 8 mmol/L). Intermittent hemodialysis was initiated, but her acidosis worsened. She developed hypotension requiring norepinephrine and subsequently deteriorated neurologically. Despite 2 hemodialysis sessions, she progressed to cardiac arrest and died. This case demonstrates that massive metformin overdose can overwhelm normal metabolic and clearance mechanisms, resulting in refractory lactic acidosis. Even with early hemodialysis, tissue sequestration of metformin and ongoing mitochondrial dysfunction may sustain lactate overproduction. Massive metformin overdose can be fatal even in healthy individuals. Close monitoring is essential, and prolonged or continuous renal replacement therapies may be warranted when initial dialysis fails to correct severe acidosis.