Editor-In-Chief: C. Michael Gibson, M.S., M.D. 
Microvascular disease or microangiopathy is a disease process affecting small blood vessels in the body.
This sometimes occurs when a person has had diabetes mellitus for a long time. High blood glucose levels cause the endothelial cells lining the blood vessels to take in more glucose than normal (these cells do not depend on insulin). They then form more glycoproteins on their surface than normal, and also cause the basement membrane to grow thicker and weaker. The walls of the vessels become abnormally thick but weak, and therefore they bleed, leak protein, and slow the flow of blood through the body. Then some cells, for example in the retina (diabetic retinopathy) or kidney (diabetic nephropathy), may not get enough blood and may be damaged. Nerves, if not sufficiently supplied with blood, are also damaged which may lead to loss of function (diabetic neuropathy).
Massive microangiopathy may cause microangiopathic hemolytic anemia (MAHA).