The article summarizes the nature and causes of the insulin resistance, its relation to the metabolic syndrome, and to the cardiovascular diseases. Insulin resistance can be defined as a set of abnormal clinical symptoms accompanied by lower tissue sensitivity to insulin. Metabolic syndrome, whose major components are impairments of glucose homeostase, obesity, dyslipidemia and arterial hypertension, represents an important risk factor for the development of diabetes mellitus type 2 and for the development of cardiovascular diseases. Possible factors, which can influence those relations, e.g., chronic inflammations, endothelial dysfunction and oxidation stress are discussed. The primary aims for the positive influencing the metabolic syndrome is the prevention of the development of diabetes mellitus type 2 and that of cardiovascular diseases. To approach those goals, the use of non-pharmacologic means (diet, appropriate physical activity) and pharmacologic (treatment of dyslipidemia, namely by statins and fibrates; management of hypertension, specifically by angiotensin-converging enzyme inhibitors, by angiotensin-receptor blockers, by glitazoe administration and by antithrombotic treatment) can be recommended.