--especially of the small fibers, have a vascular component to them; diabetic neuropathy is usually thought of as mainly ischemic in nature, in that the nerves that control the smaller blood vessels are affected, but this can work the other way around, as well, in that damage to small blood vessels may make nerves that depend on them for oxygen, nourishment, and waste removal may be compromised and thus cause damage to the function of the nerves. This also happens in many autoimmune neuropathies, particularly those associated with the anti-nuclear antibody conditions in the lupus/rheumatoid arthritis family of diseases.

It may be hard to pull apart the effects of blood vessel problems from the effect on nerves vs. the effect of nerve problems on blood vessels--they are often conflating and mutually reinforcing, like a feedback loop. Obviously, one wants to arrest the processes going on so both get a chance to heal, if that's possible.