Osmotic demyelination syndrome is a rare condition reported mainly in the case of rapid correction of hyponatremia, but it can occur even in the case of complicated diabetes mellitus either during rapid correction of hyperglycemia or anytime during the complicated diabetes mellitus. We report a case of complicated diabetes mellitus developing osmotic demyelination syndrome. The patient had presented with altered sensorium and seizure, which was initially diagnosed as hyperglycemia, but during his treatment, the magnetic resonance imaging of brain revealed central pontine myelinolysis. Our search on the causes of osmotic demyelination syndrome other than rapid correction of hyponatremia has revealed several other causes like autoimmune liver disease, Sjogren's syndrome and non-Hodgkin's lymphoma in addition to diabetes mellitus.