The endothelin receptor antagonist bosentan improves peripheral endothelial function in patients with type 2 diabetes mellitus and microalbuminuria: a randomised trial.

Aims/hypothesis: Endothelial dysfunction is important in the development of vascular complications in diabetes. Patients with type 2 diabetes have increased production of the vasoconstrictor and pro-inflammatory peptide, endothelin-1. Short-term intra-arterial administration of endothelin antagonists improves endothelium-dependent vasodilatation in patients with type 2 diabetes. We tested the hypothesis that oral administration of the dual endothelin receptor antagonist, bosentan, improves peripheral endothelial function in patients with type 2 diabetes and microalbuminuria. Methods: This placebo-controlled and double-blind study was performed on 46 patients with type 2 diabetes and microalbuminuria (urine albumin/creatinine ratio >3 mg/mmol) at a medical university department. Patients were randomised to bosentan, 125 mg two times per day ( n = 28), or placebo ( n = 28) for 4 weeks. The computer-generated randomisation code was kept in sealed envelopes. Patients and people doing examinations or assessing outcomes were blinded. The primary endpoint was change in microvascular endothelium-dependent vasodilatation, based on change in digital reactive hyperaemia index. The secondary endpoint was change in brachial artery flow-mediated vasodilatation. Results: Reactive hyperaemia index increased from 1.73 ± 0.43 (mean ± SD) at baseline to 2.08 ± 0.59 at follow-up ( p < 0.05) in the bosentan group ( n = 22), but did not change in the placebo group (1.84 ± 0.49 to 1.87 ± 0.47; n = 24). The change in reactive hyperaemia index from baseline was greater in the bosentan group than in the placebo group ( p < 0.05). Nitroglycerine-induced digital hyperaemia was not affected. Brachial artery flow-mediated vasodilatation and blood pressure did not change during treatment. Conclusions/interpretation: Oral treatment of 4 weeks duration with the dual endothelin receptor antagonist, bosentan, improves peripheral endothelial function in patients with type 2 diabetes and microalbuminuria. Trial Registration:: ClinicalTrial.gov NCT01357109; Karolinska Clinical Trial Registration Identifier CT20090017 (see ) Funding:: Research Council of Sweden, Swedish Heart and Lung Foundation, Novo Nordisk Foundation, Karolinska Institutet/Stockholm County Council Strategic Cardiovascular Programme, Gustav V and Queen Victoria Foundation, the Family Erling Persson Foundation, Actelion Pharmaceuticals and Actelion Research Award. [ABSTRACT FROM AUTHOR]