Hemorheologic changes in diabetes and their role in increased atherogenesis

Diabetes is associated with increased frequency, severity and altered distribution of atherosclerosis. This association suggests a number of possibilities in the pathogenesis of atheroclerosis because of the multitude of the changes produced by diabetes. Characteristic features of localization of atherosclerosis indicate that local blood flow patterns increase local macromolecule permeability by applying multidirectional shear stress to the endothelium at sites of separated flow. Diabetes is known to affect the flow properties of blood increasing its low shear rate viscosity and thixotropy. It would therefore be expected to increase the local shear stress burden in atherosclerosis-prone arterial sites. We are currently modifying our rotational viscometer to assess directly the difference in shear stress pattern between nondiabetic and diabetic blood when shearing is abruptly slowed and then accelerated, as occurs physiologically in arterial areas of separated flow. Our preliminary results are currently limited by a long acceleration response time, but indicate already that blood normally behaves very efficiently during decreasing and increasing flow but does produce and elevated shear stress near stagnation points in blood flow.