FROM HEMOBIOLOGY TO VASCULAR-DISEASE - A REVIEW OF THE POTENTIAL OF GLICLAZIDE TO INFLUENCE THE PATHOGENESIS OF DIABETIC VASCULAR-DISEASE

Patients with type II diabetes commonly die from thrombotic vascular disease, Large vessel occlusion due to thrombosis or atherosclerotic stenosis is a process accelerated by diabetes and results in premature death. Diabetic small vessel disease, with its unique microangiopathic process, underlies many of the large vessel changes as well as causing retinopathy and nephropathy. The microangiopathic changes produce a prothrombotic tendency that has been widely reported in type II diabetes. There is reduced endothelial cell production of prostacyclin and the activators of fibrinolysis, together with increased platelet reactivity. In addition, there is increased lipid peroxidation and oxidative stress due to excess free-radical activity and impaired antioxidant defenses particularly in the presence of microvascular disease. The development of many of these abnormalities is associated with poor long-term glycemic control. However, the changes are also seen in atherosclerosis in nondiabetic patients where the progression of the disease can be modified by antiplatelet agents and antioxidants. The process of vascular damage is accelerated by diabetes, often due to co-existing disease and aging, although it is now clear that improvement in long-term glycemic control by lowering blood glucose levels to near to the nondiabetic state reduces the development of small and large vessel disease. Although the biochemical mechanism underlying this observation remains uncertain, protein glycosylation and increased platelet reactivity are implicated and interrelated. Increased oxidative stress due to excess free-radical activity may be central to diabetic vascular disease as endothelial cell damage, lipoprotein oxidation, modification of both platelet reactivity and arachidonic acid cascade are all properties of free radicals and their reaction products lipid peroxides. All sulfonylureas are excellent hypoglycemic agents and improve long-term prognosis, but gliclazide has additional effects in modulating the prothrombotic tendency of diabetes as it has powerful free-radical scavenging properties. This unique effect associated with improvements in platelet reactivity and fibrinolysis is independent of glycemic control and may prevent vascular disease or slow its progression.