Aim: To evaluate the association of reserve-pulse pressure (reserve-PP).with coronary flow reserve and diastolic function in prediabetics subjects. [Reseveve PP= Exercise pulse pressure minus rest pulse pressure). Methods: Out of 159 patients without known CAD who were referred for coronary angiography due to typical chest pain and had normal coronary on coronary angiography, we studied 92 patients (mean age 53 ± 14 years after exclusion of patients with overt diabetes mellitus. All studied patients were subjected to echo-Doppler assessment, transthoracic assessment of coronary flow reserve (CFR) and analysis of the exercise stress test. Results: Reserve-PP was significantly lower in prediabetic compared to nondiabetic subjects (P<0.001). In addition the recovery heart rate was significantly higher in prediabetics. Prediabetic subjects had a significantly lower CFR than nondiabetic subjects (P<0.001). Reserve-PP was significantly correlated with CFR (r=0.612; P<0.0001) and inversely correlated with E/E’ (r= -0.445; P<0.001). ROC analysis showed that a cut-off value of <4.5 mmHg for reserve-PP had a sensitivity of 93% and specificity of 72% (AUC was 0.864; P<0.001) in prediction of impaired CFR prediabetic patients. Conclusion: We have shown that pulse pressure reserve was blunted and associated with significant impairment in CFR and diastolic dysfunction in prediabetics. Reserve-PP might be considered a simple, non-invasive surrogate marker for subclinical atherosclerosis and diastolic dysfunction in patients with risk for coronary artery disease. Keywords: Reserve pulse pressure; Normal coronary arteries; Prediabetes