In this study brainstem auditory evoked potentials (BAEPs), median nerve conduction velocities (CV) and early somatosensory evoked potentials ( SEPs), were employed as indices of neural conduction properties in a group of young insulin dependent diabetics (five males and five females) and a group of nondiabetic controls (five males and five females). The median nerve CV was determined from 64 summated nerve responses recorded at the elbow. The nerve was stimulated at the wrist using 0.2 msec square wave electrical pulses. The SEP was recorded from scalp electrodes using the same median nerve stimulation technique as for the CV measure. The BAEPs were produced by recording responses to 7 0 dB SL clicks delivered to the right ear at a rate of 10 per second. Measures of central transmission time were determined from each of the EP modalities. The time interval between BAEP waves I and V determined the BAEP CTT. SEP waves P9 to Pl4 determined the earliest SEP CTT measure.
Comparisons between the two diagnostic groups yielded the following results: The diabetic group evidenced a significant (p = 0, 02) slowing of the median nerve, 53 meters per second for the diabetic group versus 59 meters per second for the nondiabetic group. With height covaried out, only the SEP Pl4 latency showed a significant diagnostic group difference. More interesting were the findings for the principal SEP CTT measure. The diabetic group had significantly (p = 0.01) longer CTTs from P9 to Pl4, 5.0 msec as opposed to 4,2 msec for the nondiabetic group. The diabetic group also had significantly (p = 0.03) longer CTTs for the BAEP, 4.2 msec versus 4.0 msec for the nondiabetic group. Although the magnitude of the diagnostic group differences are small, the median nerve CV, SEP CTT, and BAEP CTT measures indicate that diabetic neuropathy is pervasive, occurring centrally, as well as peripherally, as early as young adulthood in juvenile onset, insulin dependent diabetics