The effect of diabetes mellitus type 2, on endothelial function and inflammatory process in patients with coronary artery disease

Diabetes mellitus type 2 (DM) and coronary artery disease (CAD) are both associated with endothelial dysfunction. Serum levels of soluble vascular cell adhesion molecule (sVCAM-1), interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-a) are increased in patients with CAD. We examined the effects DM on endothelial function and serum levels of IL-6, TNF-a, sICAM-1 and sVCAM-1 in patients with CAD. We studied 53 patients with CAD+DM, 20 patients with DM without CAD and 21 healthy adults without DM or any evidence for macroangiopathy. Forearm blood flow was measured using venous occlusion strain-gauge plethysmography. Endothelium dependent dilation (EDD) and endothelium-independent dilation (EID) were expressed as the % change of flow from baseline to the maximum flow during reactive hyperemia or after sublingual nitroglycerin administration respectively. Serum levels of IL-6, TNF-a and sVCAM-1 were determined using an immunosorbent assay (ELISA). All values were expressed as mean±SEM. EDD was not significantly different between DM+CAD (51.8±3.6%) and DM (54.4±6.1%). EDD was significantly greater in healthy (115.1±9.9%) compared to both DM+CAD or DM (p<0.01 for both). EID was not significantly different between the groups. Serum levels of TNF-a, IL-6 and sVCAM were significantly greater in the DM+CAD group (6.58±0.47 pg/ml, 4.42±1.22 pg/ml and 521±24 ng/ml) compared to both DM group (2.73±0.70 pg/ml, 1.85±0.22 pg/ml and 496±23 ng/ml respectively, p<0.05 for all) and healthy controls (0.82±0.17 pg/ml, 1.15±0.19 pg/ml and 312±26 ng/ml respectively, p<0.05 for all). Levels of IL-6, TNF-a and sVCAM-1 were also greater in DM compared to healthy group (p<0.05 for all). Both diabetes mellitus and coronary artery disease are associated with endothelial dysfunction and increased serum levels of IL-6, TNF-a and sVCAM-1. However, coronary artery disease leads to further increase in inflammatory process in patients with diabetes mellitus. These findings indicate that the inflammatory process is the major contributor in patients with diabetes mellitus type 2 associated with coronary artery disease.