The cause of erectile dysfunction in men with diabetes is usually related to a decrease in the blood supply to the penis as well as to injury to the nerves that are responsible for the erection mechanism.A decrease in testosterone production has also been identified as the cause in some men with diabetes.he emotional side. No matter what the cause of erectile dysfunction, it is likely to cause feelings of stress and other emotional reactions. Itâs also not uncommon for erection problems to cause tension in a relationship, particularly if one or both partners withdraws emotionally and the problem is not talked about.