Brainstem auditory evoked potentials (BAEPs) were recorded in 30 normoacoustic diabetic subjects, aged between 41 and 67 (55.37+7.75 yr). The result were compared with those obtained from 20 agemached, normoacoustic control subjects. The BAEPs were abnormal in 46.7% of diabetic subjects, I.e., the interpeak latencies (IPLs) were significantly increased and the amplitudes were somewhat reduced. BAEP abnormalities were not related to glucose balance, duration of disease, presence of the diabetic retinopathy or somatic neuropathy. In conclusion, diabetic neuropathy is characterized not only by somatic and autonomic nervous system involvement but also by central nervous system (CNS) involvement. Measurement of BAEPs would be one of the useful, noninvasive, simple and reproducible procedures to detect CNS lesion, even in the subclinical stages of Diabetes Mellitus.