We described a 28-year-old woman with insulinoma-induced hypoglycemic coma. Her initial diffusion-weighted MRI revealed diffuse hyperintense lesions involving bilateral hemispheric white matter. She did not respond to the initial treatment with glucose. However, after surgical removal of insulinoma, she began to recover gradually, and 1 year later, returned to her previous work. In general, the outcome of hypoglycemic coma with widespread leukoencephalopathy on MRI is thought to be poor. However, we should be aware that some of such cases could recover in the long term.