PDE5A and diabetes mellitus: Mostly conducted among a population with already well controlled diabetes, long half-life PDE5 inhibitors (tadalafil, PF-00489791) exhibited a statistically significant reduction in HbA1c with a mean difference of −0.50% (5.4 mmol/mol, 95% CI [−0.83%, −0.17%], 95% CI [−9.1 mmol/mol, −1.8 mmol/mol], p = 0.003) (Fig. 2c).