Insulin resistance and systemic hypertension.

There is a complex relation among insulin sensitivity, hypertension, and endothelial function. Although there are few prospective data on the relation between insulin levels and the development of hypertension, there is some evidence that insulin resistance precedes the onset of established hypertension in high-risk patients. Because insulin is a vasodilator, it would need to activate a variety of other potential physiologic mechanisms to play a causal role in the pathogenesis of hypertension. There are changes in the arterial wall in patients with hyperinsulinemia, and characteristic decreases in elasticity of the arterial wall have been noted in hypertensive patients with insulin resistance. Hyperglycemia, hyperinsulinemia, and hypertriglyceridemia appear to jointly contribute to increased arterial stiffness. There are, however, ethnic and racial disparities in the association of insulin, insulin sensitivity, and blood pressure, as this relation is not strongly observed in the black population in the United States and elsewhere. This may reflect complex relations among obesity, diabetes, and hypertension, which are more common in patients with African ancestry, although recent evidence supports the probability that the differences are genetically determined. Whatever the precise mechanisms, clinical investigations demonstrate the benefit of early interventions to improve insulin sensitivity and control hypertension, as well as to reduce hypercholesterolemia. In particular, enhanced insulin sensitivity may improve hypertension and its subsequent damage to vessel walls.