Insulin resistance and compensatory hyperinsulinemia are recognized not only in type 2 diabetes mellitus(DM) but also in essential hypertension(EHT), hyperlipidemia and obesity; these are known as the components of metabolic syndrome and accumulation of these components increase risk of cardiovascular diseases(CVD). When coronary angiographic findings were evaluated in patients with coronary artery disease(CAD), the severity was higher in CAD with DM than that without DM. Even in CAD without DM, the severity of coronary angiographic findings was higher in CAD with insulin resistance than that without insulin resistance. When residents of rural communities in Japan were followed 8 years, the incidence of CVD was 3.5 times higher in subjects with insulin resistance than those without insulin resistance. One of the intracellular signal transduction of insulin receptor; MAP kinase may be concerned atherosclerotic mechanisms of insulin resistance. These findings suggest that insulin resistance is a significant background of atherosclerosis, and insulin resistance is one of the major facilitation factors of genesis and progression of CVD.