Aim: To assess the behavior of patients with diabetes mellitus (DM) and erectile dysfunction (ED) during 10 consecutive years of treatment with self-injection of vasoactive drugs. Methods: Thirty-eight diabetic men, including 12with type Ⅰ and 26 with type Ⅱ diabetes, were followed up regularly for 10 years after they began self-injecting for severe ED. Real time rigidity assessment was used for the objective determination of the initial dosage and then doses were regulated in order to introduce an erection suitable for penetration and maintenance of erection for approximately 30 min. Patients were followed up every two months, and doses were increased only when the treatment response was not satisfactory. Results: The number of injections used per year by the patients was reduced each year (mean numbers: 50 in the first year and 22.5 in the 10th) and treatment shifted towards stronger therapeutic modalities (mixtures of vasoactive drugs instead of prostaglandin El alone). Type Ⅰ diabetic men were standardized to a level of treatment as early as 5 years after the initiation of treatment. That level was finally reached by type Ⅱ patients after another 4-5 years. Conclusion: Treatment with self-injections of vasoactive drugs in diabetic men with severe ED is a safe and effective alternative in the long term. Diabetic men of both types show the same preferences in quality and quantity of treatment after 10 years. The key point for maintenance in treatment is the adjustment of the therapeutic method and dosage to optimal levels for satisfactory erections.