Impact of Diabetes Duration on Major Adverse Cardiac Events in Patients with Non-Obstructive Coronary Artery Disease

<b>Background/Objectives:</b> Diabetes mellitus is a substantial risk factor for coronary artery disease (CAD). Diabetes duration is linked to clinical outcomes in CAD patients. This study aimed to investigate the impact of diabetes duration on major adverse cardiovascular and cerebrovascular outcomes, as well as all-cause mortality, in Korean patients diagnosed with non-obstructive CAD. <b>Methods:</b> This non-randomized, retrospective, single-center study was based on the medical records of 4287 patients who underwent coronary angiography from 1 January 2010 to 31 December 2015. Of these patients, 517 with non-obstructive CAD-defined as 20-49% coronary artery stenosis-were identified and categorized into three groups based on diabetes duration: those without diabetes, those with diabetes for <10 years, and those with diabetes for ≥10 years. <b>Results:</b> Over a median follow-up period of 60 months, the risk of major adverse cardiovascular and cerebrovascular events (MACCEs) increased nearly fourfold in patients who had non-obstructive CAD and diabetes for ≥10 years compared to those without diabetes, even after adjusting for covariates (adjusted hazard ratio [HR] 4.61, 95% confidence interval [CI] 2.04-10.40, <i>p</i> < 0.001). The risks of cardiovascular death and non-fatal stroke were also significantly higher in patients who had diabetes for ≥10 years compared to non-diabetic patients (adjusted HR 12.42, 95% CI 2.33-66.22, <i>p</i> = 0.003, adjusted HR 4.97, 95% CI 1.88-13.19, <i>p</i> = 0.001, respectively). <b>Conclusions:</b> Patients with non-obstructive CAD and a longer duration of diabetes exhibited a higher risk of MACCEs. Diabetes duration could be an important factor in predicting mortality in patients with non-obstructive CAD.