The Effect of Vildagliptin Based Treatment Versus Sulfonylurea on Glycemic Variability, Oxidative Stress, GLP-1, and Endothelial Function in Patients With Type 2 Diabetes

• Change in mean amplitude of glycemic excursion(MAGE) for 12 weeks(12weeks - 0 week). [ Time Frame: 0 week and 12 weeks ] [ Designated as safety issue: No ]
  To compare the effect of vildagliptin based treatment for 12 weeks on glycemic variability with sulfonylurea using continuous glucose monitoring system(CGMS).
  
  

• Change from baseline in oxidative stress markers and inflammatory markers at 12 weeks. Change from baseline in endothelial cell function at 12 weeks. [ Time Frame: 0 week and 12 weeks ] [ Designated as safety issue: No ]
  1. To evaluate the change of oxidative stress markers and inflammatory markers from baseline.
  2. To evaluate the change of endothelial cell function using high-resolution ultrasonography to measure brachial artery flow-mediated dilation (FMD) from baseline.
  
  

Recently, improved understanding of the incretin effect on the pathophysiology of type 2 diabetes has led to development of new agent for hypoglycemic therapy. Vildagliptin is a potent and highly selective dipeptidyl peptidase-4 (DPP-4) inhibitor that augments the active glucagon-like peptide(GLP)-1 concentration, increases insulin secretion and improves glucose tolerance. Vildagliptin has a similar glucose lowering effect, but lower hypoglycemic events, as compared to glimepiride. Vildagliptin could improve not only the mean glycemic control but also 24 hour glycemic fluctuation by restoring the physiologic pattern of insulin and glucagon secretion. Furthermore, decreased postprandial glycemic excursion might reduce the oxidative stress markers and improve endothelial dysfunction. Those effects might be amplified in Asian patients because of prominent early phase insulin secretory defects accompanied with relatively less degree of insulin resistance. In addition, GLP-1 and GLP-1 analogues exert direct beneficial effects on endothelium-dependent vasodilatation. Therefore DPP-4 inhibitors may directly improve endothelial dysfunction.

Based on this assumption, this research will focus on the effect of vildagliptin on glycemic variability, oxidative stress markers and endothelial cell function compared to long acting sulfonylurea glimepiride in type 2 diabetic patients with inadequate glycemic control on metformin.