 Recently, the investigators found that a significant proportion of subjects in a general population shows attenuated secretion of active GLP-1 in response to oral glucose loading and that the insufficient secretion of GLP-1 was independently associated with elevation of blood pressure BP Yoshihara et al. PLoS One 2013;8:e67578. In that study, it was also found that the amount of GLP-1 secreted after glucose loading was not correlated with any of conventional serum lipid parameters i.e., triglyceride, LDL-cholesterol and HDL-cholesterol or plasma insulin level. These findings suggest that insufficiency of GLP-1 secretion may promote atherosclerosis and formation of coronary plaques. Furthermore, lack of correlation between response of active GLP-1 secretion and serum lipids or plasma insulin indicates that insufficient secretion of active GLP-1 may be a hidden risk factor of atherosclerotic vascular disease. Based on those results in a previous study, the investigators designed the present study. 