Microvascular Abnormalities in Diabetes Mellitus

Diabetes is a group of diseases that result from the lack of or resistance to insulin. These two situations are the large-scale and most basic explanation for all of the abnormalities in diabetes mellitus types 1 and 2, respectively. The biochemistry and consequent anatomic and physiologic abnormalities in these diseases differ.

Biochemical abnormalities explain the macro- and micro-vascular abnormalities. For every chronic complication there is an anatomic (i.e. vascular) and a biochemical explanation. The acute complications such as diabetic ketoacidosis, hyperosmolar coma and hypoglycemic episodes are mainly explained on the basis of biochemical abnormalities that will be discussed separately.

Anatomic Pathologic Findings

• hyaline thickening of the vascular wall
• increased extracellular matrix
• increased deposition of Periodic-acid-Schiff-positive substances in vascular walls
• occlusion of vessel lumina
• microthrombi inside the capillaries
• swelling of the endothelial cells
• thickened basement membranes
• neovascularization with abnormally high proliferative changes
• loss of pericytes
• microaneurysm formation
• increased vascular permeability

Localization of Abnormal Microvascular Findings

• perineurial and endoneurial vessels
• glomerulus
• heart
• retina
• brain

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