Thirty-seven diabetic men selected to exclude the confounding effects
of other medical illnesses and nondiabetic medications and 53 healthy
controls underwent extensive psychosexual and medical evaluations and
penile blood pressure assessments by ultrasonic Doppler measurement an
d mercury strain-gauge plethysmography. There was a significant negati
ve correlation between age and the penile-brachial index (PBI) in the
diabetic but not in the control group. The impotent diabetic group had
significantly lower PBI than nondysfunctional diabetic and healthy co
ntrol subjects. Diabetic type, complications, and adequacy of metaboli
c control were not statistically related to PBI. Although the PBI may
not have diagnostic utility for individual patients, it may provide a
valuable noninvasive physiologic measure of penile vascular changes in
studies on the aged and the medically ill. The processes that mediate
the interaction of diabetes and aging on penile blood pressure and er
ectile capacity deserve further investigation.