Microvascular functional abnormalities in diabetes: the role of the endothelium.

The development of techniques for measuring microvascular pressure, flow and permeability in man has allowed the construct of a pathophysiological framework for the development of diabetic microangiopathy. In insulin dependent disease the abnormalities observed conform to the haemodynamic hypothesis with early elevation of capillary pressure playing a primary role. In non insulin dependent diabetes differences are apparent, supporting the concept that changes in microvascular vasodilatory mechanisms may antedate the emergence of diabetes. Given the crucial role played by the endothelium in the regulation of local microvascular haemodynamics it is not surprising that disturbance of this tissue has been implicated in the pathogenetic process, an assertion supported by mounting experimental evidence suggesting that the nitric oxide pathway is crucially involved.