Metformin Toxicity Unmasked by Obstructive Uropathy: A Case of Metformin Associated Lactic Acidosis and Euglycemic Diabetic Ketoacidosis

Metformin-associated lactic acidosis (MALA) is a rare but life-threatening complication of metformin therapy that most commonly occurs in the setting of acute kidney injury (AKI) and impaired drug clearance. Given the widespread use of metformin for type 2 diabetes mellitus, recognition of precipitating factors for MALA remains critically important. We report a case of severe euglycemic diabetic ketoacidosis (DKA) with refractory lactic acidosis in a patient with previously unrecognized obstructive uropathy due to recurrent nephrolithiasis causing bilateral hydronephrosis and severe AKI while on metformin therapy. The patient developed profound metabolic derangements that were unresponsive to conventional medical therapy, with resolution only after emergent hemodialysis. This case highlights the importance of early recognition of AKI from obstructive uropathy as a reversible precipitant of metformin accumulation and emphasizes the role of prompt renal replacement therapy in patients with severe MALA and refractory metabolic acidosis.