[Insulin resistance syndrome and hypertension]

Insulin resistance syndrome is the theory that glucose intolerance, hyperinsulinemia, increased very low density lipoprotein triglyceride level, decreased high density lipoprotein cholesterol level, and hypertension are proposed consequences of insulin resistance. These metabolic disturbances have been shown to increase the risk of coronary artery disease. In this theory, insulin resistance and the resultant hyperinsulinemia are considered to raise blood pressure through 1) sympathetic nervous system activation, 2) renal sodium retention, 3) renin-angiotensin system stimulation, and 4) intracellular calcium accumulation in vascular smooth muscle. Indeed, metabolic disturbance and insulin resistance have been pointed out in essential hypertensives. Leptin is a recently discovered hormone produced by an adipocyte-specific ob gene, that contributes to the regulation of energy balance by informing the hypothalamus of the amount of adipose tissue in the body. As a result, the hypothalamus adjusts food intake, thermogenesis, and energy expenditure appropriately. It was clarified that ob gene expression and plasma leptin level in humans were highly correlated with the body mass index, insulin sensitivity and blood pressure. Thus, leptin could play a role in the pathophysiology of insulin-resistant hypertension.