High levels of blood glucose damage the smallest vessels in your body, the capillaries, just as they do the larger vessels. One cause of this damage may be the high levels of advanced glycation end products (AGEs) that glucose creates inside capillary cells.

AGEs bond with proteins and, by doing so, injure them. Proteins are the building blocks of your body. For example, collagen, the “scaffolding” that supports your blood vessel walls, is a type of fibrous protein. When AGEs bond with collagen in the walls of tiny capillary blood vessels, they make the vessel walls thicker and stiffer, yet weaker. Gaps open in the vessel walls. The tiny vessels start to bleed and leak plasma protein. This condition is termed diabetic microangiopathy, disease of the small blood vessels.

Researchers have also found that the presence of high levels of AGEs in your blood vessels also lowers the levels of nitrous oxide, a chemical important for allowing your blood vessels to relax and dilate (become wider). Increased constriction of the blood vessels can lead to high blood pressure.