Background/objectives We performed a prospective study to investigate markers of percutaneous coronary intervention (PCI) related microvascular injury. Methods Consecutive patients undergoing PCI for stable angina were studied. The index of microvascular resistance (IMR) was measured using a temperature and pressure sensing guidewire (TPSG) before and after single vessel PCI. Basal transit-time (TmnBase), that reflected non-hyperemic blood flow was also measured. Fasting bloods were taken to measure blood sugar, HbA1c and lipids. Asymmetric dimethylarginine (ADMA) was also measured as a marker of systemic endothelial function. Results 55 patients were included in the study. Mean age was 59.9 ± 11.2, 74.1% male. There was no significant difference in IMR post PCI compared with pre PCI values (IMR pre PCI = 16.96 [11.5,25.38] vs. IMR post PCI 14.2 [10.37,26.25] p = 0.96). IMR post PCI was higher in diabetic (DM) patients compared with non-diabetics [IMR post DM = 22.72 (13.35,42.91) vs. no DM = 13.9 (10.18,21.45), p = 0.02]. Fasting blood sugar, HbA1c and IMR pre PCI were correlated with post PCI IMR. IMR pre PCI, HbA1C and fasting glucose were higher in patients who developed PCI related microvascular dysfunction. The strongest independent predictor of post PCI IMR was the pre PCI IMR. Conclusion The baseline status of the microcirculation is an important determinant of post PCI microvascular function. Diabetics appear to have higher post PCI IMR.