Osmotic demyelination without hyponatremia: the role of glycemic variability in a complex patient with diabetes.

Osmotic demyelination syndrome (ODS) is classically associated with rapid correction of hyponatremia; however, non-sodium osmotic shifts remain underrecognized. We report a young man with poorly controlled type 1 diabetes and extreme glycemic variability (13-486 mg/dL), admitted with cardiorenal syndrome requiring dialysis, who developed progressive neurological deficits. Brain MRI demonstrated findings consistent with extrapontine ODS despite stable sodium levels. Alternative etiologies were excluded, supporting glycemic variability and osmotic instability as key contributors, potentially exacerbated by dialysis disequilibrium. This case expands the pathophysiological spectrum of ODS and highlights glycemic variability as a clinically relevant, yet overlooked, risk factor.