This is one reason why damage tends to occur in these areas of the body, such as in nerve and kidney cells, and in small blood vessels like those in the eyes. When blood sugars are high, these cells have high interior glucose levels. The excess glucose makes it impossible for cells or organs to function as they are meant to. They fail to produce key enzymes, fail to repair themselves and fail to transport nutrients needed in the cells. Nerve cells, are vulnerable also because of their shape.
Many nerve cells are extremely long compared to their width.
Each nerve depends on thousands of tiny blood vessels along its path to receive oxygen, fuel, and other nutrients. If one or more of these supporting microvessels become damaged, that part of the nerve is also damaged. 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.