Changes in carotid arterial wall viscosity and carotid arterial stiffness in type 2 diabetes patients.

BACKGROUND AND AIMS: Changes in arterial wall viscosity (AWW) and stiffness during type 2 diabetes (T2D) have been little investigated. We explored changes in carotid AWV considering change in arterial stiffness and loading conditions, in patients with T2D. METHODS: This cross-sectional, monocentric study compared 19 middle-aged patients with T2D to 30 non-diabetic (ND) controls. The absolute viscosity (W(V)) was determined as the area of the pressure-lumen cross-sectional area (P-LCSA) loop obtained by carotid tonometry and contralateral echo-tracking. The relative viscosity was determined as the ratio between W(V) and the elastic energy stored within the arterial wall (W(V)/W(E)). Carotid geometry, midwall stress, distensibility and elastic modulus were also compared between groups. RESULTS: T2D patients were older and more frequently had hypertension. Internal diameter, mean central and pulse blood pressure were higher in T2D patients but midwall stress was similar compared to ND controls. W(V) and W(V)/W(E) were higher in T2D patients when compared with ND controls (23 [16-41] vs. 11 [7-18] mm Hg.mm(2), p=0.007 and 21% [17-25] vs. 12% [8-17], p < 0.001 respectively) even after adjustment on confounding factors. Carotid arterial stiffness was higher in T2D patients, but after adjustment this difference was only observed for the highest levels of midwall stress. CONCLUSIONS: Carotid AWV and stiffness are increased in T2D patients but only AWV is significantly increased after considering loading conditions. Whether this increase in energy dissipation within the arterial wall contributes to alter cardiovascular coupling in T2D remains to be established.