BACKGROUND: We have previously found that acute intravenous infusion of an ACE inhibitor normalized the reduced coronary vasomotor function in type 2 diabetes. The aim of the present study was to extend this investigation to an angiotensin II receptor blocker (ARB) administered orally in normotensive, asymptomatic type 2 diabetes patients without albuminuria. RESULTS: Fourteen type 2 diabetes patients were included. Each patient had myocardial perfusion measured by PET at three occasions: at baseline, following 3 weeks of treatment with 50mg/d and following another 3 weeks of treatment with 100mg/d of losartan. Baseline myocardial perfusion was similar at all three sessions (0.89+/-0.05, 0.90+/-0.08 and 0.84+/-0.05mL/(ming) tissue, respectively). Likewise, maximal hyperaemic perfusion after i.v. dipyridamole (0.56mg/kg bwt) was low but similar at the three sessions (2.01+/-0.14, 2.05+/-0.17 and 1.90+/-0.20mL/(ming) tissue, respectively). Myocardial perfusion reserve, i.e. maximal hyperaemic flow relative to baseline flow, was also low, but similar before and after treatment with losartan (2.36+/-0.24, 2.44+/-0.24 and 2.62+/-0.42mL/(ming) tissue, respectively). CONCLUSIONS: Oral treatment with an ARB did not normalize coronary vasomotor function in type 2 diabetes patients without cardiovascular disease.