Phosphodiesterase 5 inhibition improves beta-cell function in metabolic syndrome

This study tested the hypothesis that phosphodiesterase 5 inhibition alone or in combination with ACE inhibition improves glucose homeostasis and fibrinolysis in individuals with metabolic syndrome.

Insulin sensitivity, beta-cell function, and fibrinolytic parameters were measured in 18 adults with metabolic syndrome on 4 separate days after a randomized, crossover, double-blind, 3-week treatment with placebo, ramipril (10 mg/day), tadalafil (10 mg o.d.), and ramipril plus tadalafil.

Ramipril decreased systolic and diastolic blood pressure, ACE activity, and angiotensin II and increased plasma renin activity. Ramipril did not affect insulin sensitivity or beta-cell function. In contrast, tadalafil improved beta-cell function (P = 0.01). This effect was observed in women (331.9 +/- 209.3 vs. 154.4 +/- 48.0 32 micro x mmol(-1) x l(-1), respectively, for tadalafil treatment vs. placebo; P = 0.01) but not in men. There was no effect of any treatment on fibrinolysis. CONCLUSIONS Phosphodiesterase 5 inhibition may represent a novel strategy for improving beta-cell function in metabolic syndrome.