Electrical signals in these damaged nerves can then no longer pass, or they pass at a slower speed. This dependence on numerous small blood vessels is why the longest nerves going to the feet are the first to be damaged in neuropathy. Good messaging in nerves also depends on an outer protective coating called myelin. This electrical insulator is also vulnerable to damage from high blood sugars. Eyes are vulnerable because blood flow to the retina is driven by the need for oxygen.
Blood then engorges the small vessels in the retina where oxygen is low.
This excessive blood flow and blood pressure to the small blood vessels in the retina creates an environment highly likely to cause damage. But these risks become magnified by high blood sugars. High blood sugars create harmful changes in LDL, HDL, and triglyceride levels, increased clotting, higher blood pressure, and altered blood flow. People with diabetes have other, as yet unexplained, risks. The standard heart risks magnified by high blood sugars do not explain all of the excess heart damage seen in diabetes.