In patients with type 2 diabetes, sildenafil (Viagra) improves flow-mediated dilatation (FMD), an index of nitric oxide-dependent endothelial function, according to a recent report. Endothelial function is known to be impaired in type 2 diabetics, study author Dr. Vivian A. Fonseca and colleagues, from Tulane University School of Medicine in New Orleans, note. Sildenafil works by enhancing nitric oxide-induced vasorelaxation, but its effects on endothelial function in type 2 diabetics have not been assessed.
To investigate, Dr. Fonseca’s team conducted a placebo-controlled crossover trial of sildenafil therapy in 16 type 2 diabetics with erectile dysfunction but without clinical evidence of cardiac disease. The subjects received sildenafil 25 mg or placebo and then FMD was induced by occluding the brachial artery. Fourteen subjects completed the study.
Prior to treatment, occlusion of the brachial artery did not produce a significant increase in the artery’s diameter, the authors note. Similarly, no significant increase in artery diameter was noted when testing was performed after placebo had been given.
In contrast, within 1 hour of sildenafil treatment, a 15% increase in brachial artery diameter was noted during testing (p = 0.006). Moreover, after 2 weeks of sildenafil therapy, a significant increase in artery diameter was still apparent when testing was performed 24 hours after the most recent dose (p = 0.003).
The findings indicate that sildenafil improves endothelial function in type 2 diabetics "acutely as well as after prolonged use," the investigators note. "The beneficial effect of prolonged sildenafil therapy may have implications for management of erectile dysfunction as well as cardiovascular disease in patients with diabetes." Diabetes Care 2002;25:1336-1339.