Vascular Effects of Ultrafine Particles in Persons with Type 2 Diabetes

BACKGROUND Diabetes confers an increased risk for cardiovascular effects of airborne particles. OBJECTIVE We hypothesized that inhalation of elemental carbon ultrafine particles (UFP) would activate blood platelets and vascular endothelium in people with type 2 diabetes. METHODS In a randomized, double-blind, crossover trial, 19 subjects with type 2 diabetes inhaled filtered air or 50 µg/m³ elemental carbon UFP (count median diameter, 32 nm) by mouthpiece for 2 hr at rest. We repeatedly measured markers of vascular activation, coagulation, and systemic inflammation before and after exposure. RESULTS Compared with air, particle exposure increased platelet expression of CD40 ligand (CD40L) and the number of platelet-leukocyte conjugates 3.5 hr after exposure. Soluble CD40L decreased with UFP exposure. Plasma von Willebrand factor increased immediately after exposure. There were no effects of particles on plasma tissue factor, coagulation factors VII or IX, or D-dimer. CONCLUSIONS Inhalation of elemental carbon UFP for 2-hr transiently activated platelets, and possibly the vascular endothelium, in people with type 2 diabetes.