Hypoglycemic encephalopathy is a rare problem among diabetic patients who are receiving treatment with insulin or other glucose-lowering drugs. The MRIs of patients with hypoglycemic encephalopathy commonly show scattered lesions in the cerebral cortex, hippocampus and basal ganglia, but lesions in the cerebellum or brain stem are extremely rare. A 44-year-old alcoholic woman without diabetes was admitted with a semicomatose mentality and seizure with severe hypoglycemic encephalopathy with extensive brain lesions seen on MRI at the middle cerebellar peduncle and midbrain, as well as in the other brain areas.