Effect of Low-Dose Tadalafil Once Daily On Glycemic Control In Patients With Type 2 Diabetes and Erectile Dysfunction: A Randomized, Double-blind, Placebo-controlled Pilot Study

Abstract Background: Phosphodiesterase type 5 inhibitors restore nitric oxide signaling, which plays a significant role in erectile function and appears to counteract insulin resistance in animal and human models. This study was aimed to evaluate the glycemic and metabolic effects of low-dose tadalafil once a day in patients with type 2 diabetes and erectile dysfunction. Methods: A 6-month, randomized, double-blind, placebo-controlled pilot trial was conducted. Eligible patients were randomly assigned in a ratio of 2:1 to the tadalafil 5 mg and placebo groups; all patients received either tadalafil or placebo once a day. The primary efficacy endpoint was the change in the glycated hemoglobin (HbA1c) level during the 6-month study period. The secondary efficacy endpoints included metabolic parameters and erectile function. Results: Of the 68 patients who completed this study, 45 and 23 patients were allocated in the tadalafil and placebo groups, respectively. The mean HbA1c level was significantly different between the groups over the 6-month study period ( P = 0.021). After 6 months of treatment, the HbA1c decrement in the tadalafil group was greater than that in the placebo group (-0.14% ± 0.53% vs. 0.20% ± 0.69%, P = 0.030). The improvement in the International Index of Erectile Function-5 scores were significantly greater in the tadalafil group than in the placebo group at 6 months ( P = 0.003). Conclusion: This prospective pilot study shows that low-dose tadalafil once a day is effective in improving glycemic control and erectile function in patients with type 2 diabetes and erectile dysfunction. Trial Registration: KCT0005666