[Etiological analysis of male diabetic erectile dysfunction with particular emphasis on findings of vascular and neurological examinations].

We studied the nocturnal penile tumescence (NPT) value obtained by simple method and the vascular and neurological findings closely related to the ability to achieve/maintain an erection in order to investigate the causative factors of organic erectile dysfunction seen in diabetes. Studies were carried out on 62 male diabetics (32-78 y.o.). The results were as follows. 1. There were no cases of a decrease in the nocturnal penile tumescence (NPT) value among eight subjects who showed no erectile dysfunction. However, a decrease in the NPT value was recorded in 28 (85%) of 34 subjects who showed complete failure to achieve/maintain an erection. It was, therefore, surmised that there is a large organic contribution to the erectile dysfunction seen in diabetes. 2. We determined the penile blood pressure index (PBPI), the reactions of papaverine tests, conduction velocity of the dorsal nerve of the penis and the latency of the bulbocavernosus reflex. 42 (67.7%) of the 62 subjects had penile vascular disorders and the cases with severe vascular disorders were skewed to the high age brackets. There were also many cases with neuropathy involved in the ability to achieve/maintain an erection: 38 (61.2%) of the 62 subjects. Moreover, many of the subjects were found to have damage to both the blood vessels and the nerves relating to an erection, and these forms of damage were surmised to be deeply involved in the decrease in the NPT value. 3. Multivariate analysis indicated that the most important factor involved in the decrease in the NPT value was vascular damage (contribution rate: 30.8%), followed by neuropathy (6.9%). These two factors represented the most important explanatory factors of the organic erectile dysfunction seen in diabetes. 4. The contribution rate of vascular damage to the decrease in the NPT value was 18.8% for diabetic subjects under the age of 60 years, but 45.1% for subjects aged 60 years or more. The contribution rate was thus higher in the elderly subject group. On the other hand, the contribution rate of neuropathy to the decrease in the NPT value was 7.7% for diabetic subjects under the age of 60 years, but the rate decreased to 4.7% for subjects aged 60 years or more.