Etiology and Risk Factors of Erectile Dysfunction: Diabetes

The pathophysiology of ED in men with diabetes mellitus (DM) is complex and multifactorial. Men with DM, even those without significant comorbidities, suffer from a wide range of sexual dysfunction, including decreased desire and sexual satisfaction.

Prevalence of ED among diabetic men that has been reported in the literature ranges widely. Unfortunately, many studies either have not differentiated between DM Type 1 and Type 2, or were not done in Type 1 diabetics. The prevalence of ED among men with DM in the MMAS was reported at three times the general population, or 28% versus 9.6%. A more recent study evaluated selfreported ED in males with DM Type 1 and found a prevalence of 20% overall and 47.1% in those 43 years of age or older. Along with objective factors, such as decreased libido, men with DM Type 2 demonstrate organic causes with a decreased nocturnal penile tumescence.

Several cellular and molecular derangements have been described in diabetic men that contribute to the increased risk of ED in this population. Vascular injury is an important cause of ED in this population. At gross anatomical level, men with diabetes have an increased prevalence of cavernosal arterial insufficiency, thus impaired arterial response, on ultrasound.

An early study reported impaired endothelial-mediated vasodilation upon exposure to acetylcholine, a parasympathetic agent, in cavernosal tissue of diabetic men with ED.

Since this study, endothelial dysfunction in cavernosal tissue of diabetic men has been characterized by abnormalities including, but not limited to, increased apoptosis, oxidative stress, and overactivity of protein kinase C.

Thus, the effect of DM on penile vasculature is mechanically similar to its effect on other vascular structures throughout the body. Although advanced glycation endproducts have been demonstrated in cavernosal tissue, their significance remains unclear.While a majority of research has focused on diabetic ED as vascular phenomenon, there is at least correlational evidence that autonomic neuropathy plays a role in the development of ED in diabetics. The existence of ED in men with diabetes is also predicted by age and other complications of diabetes, such as retinopathy and depression