The link between impotence and diabetes has been suspected since the 1700s, but it has been only within the last few decades that it has been scientifically investigated and confirmed. Of the 5 million diabetic men in the United States, 30% to 60% suffer from impotence, a complication of their disease that many of them fear more than any other, including blindness. Diabetes is the leading physiologic cause of impotence, and it occurs in both insulin-dependent and non-insulin dependent patients. In most cases, there is no relationship between the control, the duration, or the severity of diabetes and the occurrence of impotence. Treatment methods range from adjustments in nutrition to penile implants.