The Effects Of Vitamin E-Vitamin C Combination Therapy On Glucose Metabolism And Cardiovascular Complications In IGT Patients

Impaired glucose tolerance (IGT) is the early stage of type 2 diabetes, and tends to increase the risk for development of diabetes. In addition to insulin resistance and slightly abnormal in glucose metabolism, abnormal lipid and protein metabolism are common in IGT patients, showing obesity, high levels of triglyceride, low density lipoproteins cholesterol, and low levels of high density lipoproteins cholesterol. The complications related to diabetes increases in IGT patients. Therefore, early treatment is important to prevent development diabetes and its complications in IGT patients.The mechanisms of development diabetes and its complications in IGT patients is unclear by now. But growing evidences have showed that increased oxidative stress and system inflammation are common surrogates of the diabetes state. In diabetic patients, an increase in plasma free radical levels has been associated with a decline in P cell respones to glucose and insulin action. Oxidative stress and system inflammation also have been believed to be the important factor in genesis of diabetic chronic complications. Oxidative stress and system inflammation have been found in IGT patients, in light of such evidence, they may play important roles in developing diabetes and its complications in IGT patients.Gultathione (GSH) is present in various human biological fluids and cells. The physiological relevance of this compound is related to its involvement in protein and nucleotide synthesis, as well as its antioxidant properties. The GSH/oxidized glutathione (GSSH) is crucial to maintain a normal cell metabolism. The presence of an exaggerated rate of oxygen radical production associated with a decrease in GSH/GSSH ratio. Such a phenomenon might decease the protective effect of GSH oncells membrane and affect the physiochemical integrity of plasma membranes and the membrane permeability. That may impaire insulin-mediated glucose uptake by cells and tissues, and decrease glucose disposal. Furthermore, the glycolytic enzyme activities can be inhibited by free radicals, and increased GSH/GSSH ratio was associated with stronger increase in whole body glucose desposal and in nonoxidative glucose metabolism.Enhanced oxidation of LDLs are belived to contribute to excess risk of cadiovascular disease in diabetes. Oxidation of LDL that becomes trapped in artery wall is widely regarded as an improtant step in the development of atherosclerosis. There is an evidence that mildly oxidized LDL enhances the expression of porinflammatory cytokines, chemoattractants, and cellular adhesion molecules by endothelial cells. These molecules promote adhesion of monocytes go the vascular endothelium followed by transmigration of adhered cells in to the intima where they are retained and transformed in to macrophages. Macrophages avidly internalize oxidized LDL via scavenger receptors to form lipid-filled cells-foma cells that are the hallmark of the early atherosclerotic lesion. Increased inflammatory activity is also believed to predispose established atherosclerotic plaques to rupture, witch can lead to a coronary event. Plasma Oreacting protein (C-RP) is a sensitive marker of systemic inflammation, and chronically high levels predicts increased risk of future coronary events.Vitamin E and vitamin C are physiological constituent of blood plasma with potent antioxidant power. Vitamin E is lipophilic and inhibits lipid peroxidation, scavenging lipid peroxyl radical to yield lipid hydroperoxides and the tocopheroxyl radical. Vitamin C, a water-soluble vitamin, functions cooperatively with vitamin E by regenerating tocopherol from the tocopheroxyl. It has been demonstrated that orally administrated vitamin E and vitamin C enhance concentrations of GSH in plamsa and red blood cells and improve peripheral insulin action in health subjects and type 2 diabetes patients. Also, they have been shown to have protective effectsagainst LDL oxidation, and vitamin E might decrease plasma levels of C-RP in patients with diabetes.In light of such evidences the presen...