We report on delayed emergence of restricted diffusion on MRI after hypoglycemia. A 56-year-old man with type 2 diabetes was admitted with mental change. Initial serum glucose was 19 mg/dl. Fifteen hours after presumed symptom onset, brain imaging did not show any definite abnormality. However, areas of restricted diffusion emerged evident in both basal ganglia 9 days later. Hypoglycemia can cause delayed cytotoxic edema even after normalization of the serum glucose.