The metabolic syndrome, type 2 diabetes, and cardiovascular disease: understanding the role of insulin resistance.

The most common and clinically important complication in adults with diabetes is cardiovascular disease (CVD), which includes coronary heart disease, peripheral vascular disease, and stroke. Both type 2 diabetes and the insulin resistance syndrome are associated with a marked increase in the risk for CVD. The metabolic syndrome and the closely related insulin resistance syndrome have recently been recognized as important disorders, each being associated with an increase in CVD risk even in the absence of glucose intolerance. Given the significant public health burden of CVD, risk reduction has emerged as a significant clinical challenge for most practitioners. Diabetes and the insulin resistance syndrome are closely related disorders, with insulin resistance being more than a key pathogenic defect in type 2 diabetes. Even in the absence of glucose intolerance, these 2 disorders are both associated with a number of distinct pathologic findings, including hypertension, atherogenic dyslipidemia, a prothrombotic environment, and significant vascular and hemodynamic abnormalities that result from endothelial cell dysfunction. Insulin resistance is now recognized to be closely associated with the development of each of these risk factors. This article uses a case-based approach to discuss the unique features of insulin resistance and type 2 diabetes considered to be key contributors to CVD risk. A systematic approach to both evaluation and management is proposed, with priority given to therapies of demonstrated clinical benefit. Because of its critical and central role in the development of many CVD risk factors, targeted treatment of insulin resistance will also be discussed as such therapy may prove to be a critical component of care in years to come.