Abstract Body (Do not enter title and authors here): Introduction: Diabetes mellitus (DM) is a risk factor for coronary microvascular dysfunction (CMD) and endothelial dysfunction. These disorders and other syndromes of angina and nonobstructive coronary arteries (ANOCA) are increasingly recognized. However, the association between DM and non-CMD ANOCA endotypes, such as vasospastic angina (VA) and symptomatic myocardial bridging (MB), is not well defined. This study aims to report the findings of coronary function testing (CFT) in patients with DM and to determine the association between DM and specific ANOCA endotypes.

Methods: We conducted a retrospective study of patients who underwent clinically indicated invasive coronary angiography and CFT with intracoronary acetylcholine provocation and bolus thermodilution between January 2018 and May 2024. Data regarding patient demographics, medical history, and physiological measurements—including coronary flow reserve (CFR), index of microcirculatory resistance (IMR), fractional flow reserve (FFR), resting full-cycle ratio (RFR), and post-procedure diagnosis—were obtained.

Results: 233 patients were included, 163 (70%) were female, with a mean age of 57 ± 11 years. Of the total cohort 52 patients (22.3%) had DM. Among patients with DM, 23 (44%) had CMD, 13 (25%) had VA, 6 (12%) had mixed CMD/VA, 11 (21%) had endothelial dysfunction, and 4 (7.7%) had other phenotypes such as elevated resting flow and MB. The median CFR was reduced in patients with DM compared to those without DM (2.6 vs. 3.45; p=0.001), and the median IMR was higher (28 vs. 19; p<0.001). No statistically significant differences were found in the median FFR (0.89 vs. 0.9; p=0.375) or median RFR (0.91 vs. 0.93; p=0.1). The risk of having any ANOCA diagnosis was comparable between patients with DM and those without DM (risk ratio = 1.03 [0.92, 1.15]; p=0.67), but patients with DM had a significantly increased risk of CMD compared to patients without DM (risk ratio = 1.82 [1.22, 2.71]; p=0.0052). No association was observed between DM and any other ANOCA endotypes.

Conclusion: Our analysis revealed that DM is associated with lower CFR, higher IMR, and an increased risk of CMD. No association was found between DM and any other ANOCA endotype. These findings align with existing data using a contemporary, reproducible CFT protocol. Future studies will explore the clinical implications of these findings and evaluate the impact of glycemic control on outcomes in this patient population.