Atherosclerotic cardiovascular disease is the leading cause of premature death in patients with diabetes. Atherosclerosis is a chronic immune-mediated disease, the initiation, progression, and destabilization of which is driven and regulated by inflammatory cells. One critical event in the initiation of this vascular inflammatory disease is the adhesion of leukocytes to the activated endothelium and their migration into the vessel wall. These processes are mediated by the upregulation of adhesion molecules on endothelial cells (ECs) and an increased expression in the vascular wall of chemotactic factors to leukocytes. Monocyte binding to ECs is increased in diabetes. One major determinant of this alteration could be oxidative stress. Given the free-radical scavenging activity of gliclazide, we determined the ex vivo and in vitro effects of this drug on human monocyte binding to ECs and the molecular mechanisms involved in this effect. Our results demonstrate that short-term administration of gliclazide to patients with type 2 diabetes normalizes the levels of plasma lipid peroxides and monocyte adhesion in these subjects. Gliclazide (10 microg/mL) also reduces oxidized low-density lipoprotein (oxLDL)- and advanced glycation end product (AGE)-induced monocyte adhesion to ECs in vitro. The inhibitory effect of this drug on AGE-induced monocyte adhesion involves a reduction in EC adhesion molecule expression and inhibition of nuclear factor kappaB (NF-kappaB) activation. In addition, gliclazide inhibits oxLDL-induced monocyte adhesion to cultured human aortic vascular smooth muscle cells (HASMCs) in vitro and reduces the production of monocyte chemotactic protein-1 (MCP-1) by these cells. Taken collectively, these results show that gliclazide, at concentrations in the therapeutic range, inhibits ex vivo and in vitro monocyte adhesiveness to vascular cells. By doing so, this drug could reduce monocyte recruitment into the vessel wall and thereby contribute to attenuating the sustained inflammatory process that occurs in the atherosclerotic plaque. These findings suggest that treatment of diabetic patients with this drug may prevent or retard the development of vasculopathies associated with diabetes.