They have introduced the term endothelial dysfunction to describe some of the abnormalities in blood vessels that lead to atherosclerosis. The endothelium is the innermost layer of cells that line the blood vessels, and is the site of the early damage done by atherosclerosis. The endothelium is not simply a static, structural layer of cells but in fact is highly active and important structure in metabolism. The endothelium helps to regulates the bore of the blood vessels, to direct blood and its components to particular cells, and influence the passage of molecules into and out of the blood vessels. The endothelium has receptors for many hormones and hormone-like agents whereby its activities can be influenced.
Some scientists speculate that endothelial dysfunction is a cause of insulin resistance.
Among the hormones gaining attention are those made by cells of the intestinal tract. In response to food, these hormones are released into the blood to stimulate the pancreas to release more insulin. In a very real sense, the signal brought to the pancreas by glucose is amplified by the presence of these intestinal tract hormones. GLP-1 is the most potent of these and receiving the most attention from investigators. Proteins within our cells can also affect the binding of insulin to the surface of those cells.