Proton pump inhibitors (PPIs) are the commonly recommended treatment for gastric abnormalities. The structural scaffold of PPIs (Pantoprazole; PPZ) provides an incalculable chance of association with diverse biological receptors which indicate a huge possibility of pleiotropic therapeutic impact which needs to be explored. Recently, several studies report the cardioprotective events of PPIs, but the underlying mechanism is not clear. Four groups having six animals in each were considered for this study. STZ (50 mg/kg/i.p) was given to induced chronic diabetes mellitus (DM) and vascular endothelial dysfunction (VED). PPZ (4 mg/kg/p.o/daily for 8 weeks) was evaluated against DM induced VED by measuring endothelial relaxation, aortic/serum nitrite/nitrate concentration, asymmetric dimethylarginine (ADMA), aortic superoxide anion generation, serum thiobarbituric acid reactive substances (TBARS) and dimethylarginine dimethylaminohydrolase (DDAH) in the cell lysate of each animals group. PPZ significantly overcome the perturbed level of hyperglycemia measured by blood glucose level, increase the availability of NO measured by aortic/serum nitrite/nitrate concentration. Treatment with PPZ showed the determinate lessening of tissue injuries as it averted increase expression of VED measured by ACh-induced endothelium-dependent relaxation, and diminution in oxidative stress, plasma ADMA level, and DDAH concentration in the cell lysate. The vascular protective potential of PPZ has a strong correlation with the DDAH/ADMA/eNOS/NO signaling pathway. Furthermore, the study also explored the antioxidant activity of PPZ which may also facilitate this protective pathway by increasing the bioavailability of NO in the endothelium.