We describe a patient with noninsulin-dependent diabetes mellitus presenting with an amnestic disorder, personality change, and autonomic seizure. Magnetic resonance images of the brain showed T2-high signal lesion in the hippocampi bilaterally and nonspecific white matter disease, while single photon emission computed tomography revealed a diffuse reduction of cerebral blood flow. Sensory and auditory evoked potentials revealed delayed impulse conduction velocities in the central nervous system. Degenerative changes caused by a microvascular angiopathy related to noninsulin-dependent diabetes mellitus may underlie the central nervous system manifestations in our patient.