Comparison of Amlodipine and Aliskiren in Diabetic Hypertensive Patient With Blood Pressure Not Controlled by Losartan

Hypertension and diabetes mellitus are important risk factors for cardiovascular morbidity and mortality. Endothelial dysfunction and vascular rigidity are two pathophysiological mechanisms that may explain this relationship. Recent publications showed that both ACEi (angiotensin converting enzyme inhibitor) and ARB (angiotensin receptor blocker) were capable of improving vascular stiffness and endothelial function, and that these effects occurred despite blood pressure reduction. The major debate that persists is which drug to associate with ACEi or ARB to achieve blood pressure control in diabetic patients. Recent studies showed that even in patients under ACEi or ARB therapy there may be residual activity in the renin-angiotensin-aldosterone system (RASS). Direct renin inhibitors (DRI) are a new class of anti-hypertensive drugs that may complement the blockade of the RASS. Aliskiren was the first drug of this class that completed phase 3 studies and marketed in the 21th century. It's main advantage is that DRI may reduce angiotensin II and aldosterone synthesis without increasing renin levels. This study main objective is to assess if aliskiren is capable of enhancing vascular stiffness and endothelial function and compare theses effects to those obtained with a calcium channel blocker, amlodipine, in patients with diabetes mellitus type 2 and blood pressure not controlled by 100 mg per day of losartan. Vascular stiffness and endothelial function will be measured by: pulse wave velocity, augmentation index, brachial artery flow-mediated vasodilation, peripheral arterial tonometry (EndoPat). Another main objective is to compare plasma renin activity and concentration between those groups.