Abstract Introduction Metformin is an oral antihyperglycemic agent widely used as a first-line treatment for Type 2 Diabetes Mellitus. Although generally considered safe, metformin-associated lactic acidosis (MALA) is a rare but life-threatening complication. Vision loss, an uncommon but notable manifestation, can mimic the clinical presentation of toxic alcohol ingestion. We present a case of severe metabolic acidosis with transient bilateral vision loss, initially suspected to be methanol poisoning, later determined to be MALA. Case Description A 55-year-old female with a history of Type 2 Diabetes Mellitus presented with an acute one-day history of nausea, vomiting, and bilateral vision loss. Her history was notable for poor oral intake for one week following the loss of her husband, along with brief slurred speech and generalized weakness. Initial laboratory workup revealed severe high-anion gap metabolic acidosis with an anion gap of 42, pH 6.7, bicarbonate 3 mmol/L, lactic acid 17 mmol/L, and serum creatinine 7.2 mg/dL (baseline creatinine 0.6 mg/dL and eGFR 100 three months earlier). Shortly after arrival, the patient became unresponsive and developed pulseless electrical activity secondary to profound acidosis, with return of spontaneous circulation after 15 minutes of ACLS and aggressive bicarbonate administration. She was intubated for airway protection. Given her laboratory abnormalities, clinical deterioration, and occupational exposure to embalming agents, methanol toxicity was initially suspected. Poison control was contacted and recommended empiric IV fomepizole, IV bicarbonate, high-dose IV folic acid, and emergent CRRT/hemodialysis.Lactic acidosis rapidly improved with dialysis, and the patient demonstrated clinical recovery within 48 hours. She was extubated, and her vision returned to baseline. Toxic alcohol levels later resulted negative, and renal function gradually improved with adequate urine output. Based on her clinical course, laboratory findings, reversal of visual symptoms, and negative toxic alcohol panel, her presentation was concluded to be secondary to metformin associated lactic acidosis. Discussion Reversible bilateral vision loss in the setting of profound metabolic acidosis is a recognized but rare manifestation of metformin associated lactic acidosis. Visual symptoms likely result from retinal and cortical hypoperfusion due to severe acidemia. This differs from methanol toxicity, where formic acid accumulation causes direct optic nerve injury, commonly resulting in irreversible blindness. Overlapping clinical features between methanol toxicity and MALA can complicate early management; however, negative toxic alcohol levels and restoration of vision help clarify the diagnosis. Prompt recognition and early renal replacement therapy are essential, as both metabolic stability and visual function are potentially reversible with timely intervention. This abstract is funded by: none
Pulipaka et al. (Fri,) studied this question.