[Event-related potential in patients with diabetes mellitus]

The event-related potential (ERP) was recorded for 24 patients with diabetes mellitus (age 67.5 +/- 8.5 years, mean +/- SD) and 28 healthy controls (age 61.0 +/- 10.6 years) to elucidate the involvement of the central nervous system (CNS) in diabetes mellitus. ERP was recorded during auditory discriminative tasks. The latencies of N100, P200, N200 and P300 from the Pz region were measured. Patients with diabetes mellitus showed significant prolongation of N200 and P300 latencies compared with the normal subjects, while no significant differences in N100 and P200 latencies were found between the two groups. In six of 24 patients, the P300 latency delayed beyond the 2SD of the appropriate age-related value estimated from the normal regression line. The delay of the P300 latency was not related to either the duration of illness, therapeutic methods, or metabolic control. From the present results, it would appear that higher brain function is impaired even in diabetic patients not manifesting overt CNS signs and symptoms.