Relationship between insulin resistance and hypertension.

Patients with hypertension have been shown to be resistant to insulin-stimulated glucose uptake and to be both hyperinsulinemic and hypertriglyceridemic compared with matched normotensive control groups. These abnormalities are present before the institution of antihypertensive therapy and do not necessarily improve when blood pressure is effectively lowered. Insulin resistance, hyperinsulinemia, hypertriglyceridemia, and high blood pressure can be produced in fructose-fed Sprague-Dawley rats, but the development of these changes is inhibited by exercise training or somatostatin infusion. Furthermore, insulin-stimulated glucose uptake is lower in spontaneously hypertensive rats (SHRs) than Wistar-Kyoto rats, and this is associated with higher plasma triglyceride concentrations and blood pressure. In addition, a defect in insulin-stimulated glucose uptake can be shown in adipocytes isolated from SHRs, and the greater the degree of in vitro insulin resistance, the higher the plasma insulin concentration and blood pressure. These data strongly support the view that abnormalities of insulin and lipid metabolism are associated with high blood pressure in both patients and rodent models of experimental hypertension. In the latter context, endogenous hyperinsulinemia and hypertriglyceridemia are risk factors for coronary heart disease. The fact that antihypertensive treatment has not focused on correcting these metabolic abnormalities may explain why it has been difficult to show that lowering blood pressure decreases the risk of coronary heart disease. It can be argued that abnormalities of carbohydrate and lipoprotein metabolism play a role in both the etiology of hypertension and the clinical course of hypertensive patients.