Abnormal nerve conduction in impotent patients with diabetes mellitus.

The etiology of impotence in the diabetic population has not been clearly defined. To assess this problem, 24 impotent diabetic subjects, 21 nonimpotent diabetic subjects, and 10 subjects with psychogenic impotence were compared with nocturnal monitoring of penile tumescence and rigidity, penile arterial blood flow, and nerve conduction of the pudendal nerve. There was no statistical difference in mean age or duration of diabetes among the various study groups. All diabetic subjects who presented with complaints of impotence had severe abnormalities on nocturnal erection monitoring. There was no significant difference in the mean penile brachial index between impotent and nonimpotent diabetic subjects (P = .335). In contrast, there was a significant difference in bulbocavernosus-reflex latency times (P less than .001) between impotent (mean latency 48.4 ms) and nonimpotent (mean latency 38.7 ms) diabetic subjects. This study strongly suggests that impotence in the diabetic population is secondary to functional abnormalities of pelvic nerves and that the bulbocavernosus-reflex latency time is an excellent diagnostic test for assessing function of pelvic nerves in the diabetic individual.