The efficacy of PDE5 inhibitors in diabetic patients

BackgroundPhosphodiesterase 5 inhibitors (PDE5i), since their introduction in the late 1990s, have proven their efficacy in treating several conditions, predominantly pulmonary hypertension and erectile dysfunction where they remain the first-line therapeutic option. However, in the recent years, growing evidence from both animal and human studies has emerged to suggest the additional benefits of PDE5i in cardiovascular and metabolic disorders. This is of specific interest to the diabetes population where prevalent cardiovascular disease and metabolic dysregulation significantly contribute to the increased morbidity and mortality. ObjectivesTo examine the available data on the non-standard, pleiotropic effects of PDE5i in patients with diabetes mellitus. Materials and methodsThe review of the published background research, preclinical studies and clinical trials. ResultsIn human studies, PDE5 inhibition appeared to be associated with reduced cardiovascular mortality and overall improved clinical outcomes in those with established cardiovascular disease. PDE5i were also consistently found to reduce albuminuria in subjects with diabetic nephropathy. Furthermore, animal data suggest a plausible effect of this group of medication on sensory function and neuropathic symptoms in diabetic neuropathy as well as improved wound healing. A decrease in insulin resistance and augmentation of beta cell function seen in preclinical studies has not been consistently demonstrated in human trials. Discussion and conclusionIn animal models, PDE5 inhibition appears to decrease oxidative stress and reduce some of the micro- and macrovascular complications associated with diabetes. However, data from human trials are limited and largely inconsistent, highlighting the need for adequately powered, randomised-controlled trials in diabetic cohorts in order to fully assess the benefits of PDE5i in this group of patients.