Taking one of these tablets will not automatically produce an erection. Sexual stimulation is needed first to cause the release of nitric oxide from your penile nerves. These medications amplify that signal, allowing some men to function normally. Oral erectile dysfunction medications are not aphrodisiacs, will not cause excitement and are not needed in men who get normal erections.
Researchers have found that one particular simple sugar, present in increased levels in diabetics, interferes with the chain of events needed to achieve and maintain erection and can lead to permanent penile impairment over time.  The results, which have implications for new types of erectile dysfunction treatments targeting this mechanism of erection, are described in the August 16 issue of the Proceedings of the National Academy of Sciences.
ED has been for long time considered a problem mainly related to psychological conditions and distress. Accordingly, until phosphodiesterase type 5 inhibitors (PDE5i) were introduced, psychoanalysis and cognitive-behavioural therapy were the only option for ED. In the last few decades, ED has been recognized as a clinical consequence of several different organic diseases and the importance of vascular health in erectile function has been so emphasized that ED is now considered not only the result of vascular impairment, but also a harbinger of forthcoming cardiovascular (CV) events (17). Despite the increasing attention of research towards organic mechanisms and conditions leading to ED, it is now known that considering this symptom as entirely due to organic disorders, is as imprecise as considering it only secondary to psychological conditions. In fact, this pathogenetic dichotomy is now obsolete (1,18,19), because it is now known that ED is a multidimensional disorder deriving from the interaction of different components related to organic conditions, relational context and psychological status (20,21). Even when only one of these components is involved in the initial development of erectile impairment, eventually the other ones will appear, thus further worsening ED (21-23). The multidimensional nature of ED is still not fully accepted by health care professionals when dealing with young patients. In fact, complaints of ED in young men is often underestimated and attributed to transient and self-limiting psychological conditions, such as performance anxiety. Young patients are often reassured without any further medical investigations, including physical exam. However, organic disorders, as well as relational and psychological or psychiatric conditions, can be meaningful in determining ED in younger men. In a population of subjects seeking medical care at the Sexual Medicine and Andrology Unit of the University of Florence for sexual dysfunction, the first tertile of age (n=1,873 subjects) represents younger subjects (18–44 years). Pathogenetic components of ED in our sample are investigated by the Structured Interview on Erectile Dysfunction (SIEDY), a structured interview including 13 questions, whose answers, organized in a Likert scale, provide three scales, one for the organic subdomain [(SIEDY Scale 1); (22)], one for the relational subdomain [(SIEDY Scale 2); (23)] and one for the intrapsychic subdomain [(SIEDY Scale 3); (21)]. According to these scale scores, organic, relational and intrapsychic conditions are all significant risk factors for ED in younger patients of our population (Figure 2).
• Blood Vessels: Diabetes damages blood vessels, especially the smallest blood vessels such as those in the penis. Diabetes can also cause heart disease and other circulatory problems. Proper blood flow is absolutely crucial to achieving erection. “Erection is a hydraulic phenomenon that occurs involuntarily,” says Arturo Rolla, MD, of Harvard University School of Medicine. “Nobody can will an erection!” Anything that limits or impairs blood flow can interfere with the ability to achieve an erection, no matter how strong one’s sexual desire.