A comparison of baseline erectile function after on-demand 20 mg tadalafil vs daily 5 mg tadalafil in men with erectile dysfunction and diabetes: A prospective, observational 2-year study

Objectives: We studied whether long-term use of 5 mg tadalafil once daily improved baseline erectile function or prevented erectile dysfunction (ED) in men with diabetes. Material and Methods: Men with ED and diabetes who were naïve to PDE5 inhibitors were assigned to 20 mg tadalafil ondemand or 5 mg tadalafil once daily and asked to provide information about erectile function at the start of treatment and after 2 years. When men completed the questionnaire after 2 years of treatment, they also stopped the medication for 4 weeks to check their baseline erectile function. The primary efficacy variable was the IIEF-EF score. Secondary efficacy variables included a change in the scores IIEF Q3 and Q4 from baseline, changes in all domain scores on the IIEF from baseline, SEP2 and SEP3, and the GAQ. Rigiscan® measurements of nocturnal penile tumescence and rigidity (NPTR) were also carried out 2 years after treatment. Results: The study enrolled 118 men (mean age: 56.2yrs) and most had mild to moderate ED (57.6%): 65 patients (55.1%) were prescribed 20 mg tadalafil on demand and 53 patients (44.9%) took 5 mg tadalafil once daily. After 2 years of treatment, the daily treatment group had a significantly greater change in the IIEF-EF domain score from baseline compared with the on-demand group (7.3 vs 2.4, P < 0.0001). The changes in IIEF from baseline on Q3 (1.4 vs 0.4, P < 0.0001) and Q4 (1.4 vs 0.3, P < 0.0001) were higher in the daily group than in the on-demand group. Differences between the daily and on-demand groups were significant for SEP2 (53.8% vs 32.3%, P = 0.0003) and SEP3 (56.6% vs 15.4%, P < 0.0001). Normal EF domain scores (≥26) at the end of the study were achieved by 20.7% and 6.2% in the daily and on-demand groups, respectively (P = 0.0031). Normal patterns of NPTR at the end of the study were achieved by 13.2% only in the daily group. Conclusion: Long-term use of 5 mg tadalafil once daily was more beneficial for improving baseline erectile function or preventing ED than the on-demand pattern in men with ED and diabetes .