June 15, 2006 – Alterations in mechanisms that cause a faster progression to atherosclerotic disease links hypertension and diabetes to cardiovascular (CV) disease, affecting the heart, kidneys, brain, and eyes.
Professor A.M. Heagerty gave a brief review of some of these mechanisms in a plenary session on hypertension, diabetes and the heart at the 16th European Meeting on Hypertension held in Madrid, Spain.
The physiological response to high blood pressure in the small blood vessels is “eutrophic remodeling” that results in a narrower lumen with cells in a different position, and an increase in the number of layers and resistance, as shown by studies of the relationship between structure and function.
A study by Heagerty’s group showed elevation of systolic and diastolic blood pressures in patients with type 2 diabetes and in both type 1 and 2 diabetes there was protein loss and dyslipidemia, but no dyslipidemia in essential hypertension alone, highlighting the higher risk in patients with hypertension and diabetes.
In diabetes, there are structural differences seen in the vessels. The pathologic response to high blood pressure in diabetes is growth of the vascular wall.
Endothelial dysfunction is a “harbinger” of CV disease, with studies showing a clear relation between abnormal endothelial function and early atherosclerotic disease. Studies have shown that normotensive diabetics have abnormal function, which is worse in hypertensive diabetics. Angiotensin receptor blockers (ARBs) improve endothelial function, probably because they interfere with the renin angiotensin system and restore endothelial function, according to evidence from three studies.
It is thought that oxidized LDL reduces the production of nitric oxide and increases its degradation. Hypercholesterolemia induces increased expression of the AT1 receptors, leading to enhanced production of free radical species, and this oxidative stress results in endothelial dysfunction.
In diabetic patients with a 30% reduction in endothelial function compared to controls, 3 months of treatment with ARBs increased endothelial function, without changes in blood pressure in some patients, in a study by Heagerty and colleagues.