The aim of this study is to evaluate the effects of indapamide SR 1.5 mg on blood pressure, blood tests (glucose metabolism, lipids, minerals, and uric acid), cardiac function, endothelial and arterial function, by comparison with hydrochlorothiazide 25 mg, in patients with hypertension and type 2 diabetes mellitus. In order to achieve a better control of blood pressure in these patients, each diuretic treatments will be added to an ACE inhibitor (quinapril 10-40 mg/day). Therefore, eventually, the study will provide data on the comparison between combination indapamide SR 1.5 mg + quinapril versus hydrochlorothiazide 25 mg + quinapril.