The number of patients with diabetes is expected to increase more than three-hundred million within ten years. Moreover, in chronic diabetes the overproduction of reactive oxygen species (ROS) involves and mediates many cells damaged. Recently, thioredoxin-interacting protein (Txnip) expression and the activated NADPH oxidase enzyme (NOX2) are reported for developing ROS overproduction and causing vascular inflammation in diabetes. The study aimed to investigate the effects of curcumin, a potent antioxidant with anti-inflammatory property, on preventing diabetes-induced vascular inflammation in association with its actions on Txnip expressions and NOX2 enzyme. Male Wistar rats were divided into three groups: control (CON, n=5), diabetic (DM; streptozotocin (STZ), i.v. 55 mg/kg BW, n=5), and diabetes-treated with curcumin (DMCUR; curcumin 300mg/kgBW in corn oil, n=5). The guideline for experiment animals was suggested by the National Research Council of Thailand. The supplementation of curcumin was started at 10 days after STZ-injection. 12th week after STZ injection, iris blood perfusion and leukocyte adhesion of each rat was measured by using laser Doppler and intravital fluorescent microscopy, respectively. Plasma glucose (BG) and HbA1c were determined using enzymatic and turbidimetric immunoinhibition methods, respectively. Txnip expression, P47phox expression (marker of NOX2), and malondialdehyde (MDA) level at eye fundus were determined by Western Blot analysis and TBAR assay, respectively. Values are means±S.E.M., compared by ANOVA. The body weight and iris blood perfusion of DM (271.67±13.22 g, 246±26.99 AU) and DMCUR (258.00±17.64 g, 311.28±31.13 AU) were decreased significantly as compared to CON (424.00±28.28 g, 870.27±39.61 AU) (P < 0.001). BG and HbA1c of DM (410.33±16.77 dL, 9.47±0.47 %) and DMCUR (390.33±11.59 dL, 9.30±0.21 %) were increased significantly as compared to CON (172.83±11.08 dL, 4.00±0.06 %, P < 0.001). Interestingly, the leukocyte adhesion, p47phox expression, and MDA level in DM (33.71±0.68 cells/frame, 0.87±0.14, and 11.69±0.22 nmole/protein100µg) were increased significantly when compared to CON (3.64±0.68 cells/frame, 0.39±0.03, and 5.17±1.05 nmole/protein100µg, P < 0.05), and DMCUR (14.94±3.85 cells/frame, 0.51±0.05, and 8.36±0.63 nmole/protein100µg, P < 0.05). Txnip expression in DM (0.83±0.14) and DMCUR (0.71±0.1) were significantly higher than CON (0.45±0.06, P < 0.05). It suggested that curcumin could ameliorate diabetic vascular inflammation by decreasing ROS overproduction, reducing leukocyte-endothelium interaction, and also inhibiting NOX2 activation. Moreover the results also showed a linear correlation between the inhibitory effects of curcumin on leukocyte-endothelium interaction and NOX2 inhibition (y=0.0143x+0.3666, r=0.952, P < 0.05).