Diabetes is known to sabotage two body parts that provide essential components of an erection: nerves and blood vessels. Studies suggest that diabetic nerve damage (neuropathy) is the most important risk factor for ED in people with diabetes. If pelvic nerves that trigger penis muscles to relax are impaired, there may be a break in the chain between brain and penis, disrupting erection. Some researchers suspect that an inadequate supply of oxygen to the nerves causes this damage.
Erectile dysfunction related to medical/physical causes is often treatable but less commonly curable. In some cases of medication-induced erectile dysfunction, changes in medication may improve erections. Similarly, in men with a history of arterial trauma, surgical intervention can restore erectile dysfunction. In most cases of ED associated with a medical condition, treatment allows one to have an erection "on demand" or with the aid of medications/device (but not spontaneous).
If this treatment approach fails, it is useful, however frustrating, to start again from the beginning. Reassess the history to ensure that nothing was missed originally. Obtain labs and perform a PCDU. This will give the objective information that you might need in order to make a diagnosis of a known etiology for ED and to provide the patient reassurance that your evaluation has been thorough.
Vacuum therapy devices have a few disadvantages. One must interrupt foreplay to use them. You must use the correct-size tension ring and remove it, to prevent penile bruising, after sustaining the erection for 30 minutes. Initial use may produce some soreness. Such devices may be unsuitable for men with certain bleeding disorders. In general, vacuum constriction devices are successful in management of long-term ED.
Unfortunately, studies specifically considering the relationship between couple liaison and ED in younger men are not available. Although the aforementioned studies include also young men, thus making their results theoretically applicable even in this specific group, it should be recognized that mean age of men enrolled is usually shifted toward the middle-age, rather than younger age. It is conceivable that couple relationship can act differently in younger men because it could show peculiar characteristics likely affecting ED onset, maintenance, resolution or responsiveness to therapies, including the short duration, lack of experience in both the partners, limited privacy, fears for emotional involvement or worry for undesired pregnancies.

Khoo, J., Piantadosi, C., Duncan, R., Worthley, S. G., Jenkins, A., Noakes, M., … Wittert, G. A. (2011, October). Comparing effects of a low-energy diet and a high-protein low-fat diet on sexual and endothelial function, urinary tract symptoms, and inflammation in obese diabetic men [Abstract]. The Journal of Sexual Medicine, 8(10), 2868-75. Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/21819545
• 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.