Coronary Computed Tomographic Angiography Versus Functional Testing in Patients With Newly Diagnosed Type 2 Diabetes and Suspected Coronary Artery Disease: Real-world Evidence from the Nationwide Cohort

BACKGROUND AND OBJECTIVE: Patients with type 2 diabetes mellitus (T2DM) have an elevated risk of adverse cardiovascular events due to accelerated atherosclerosis and a higher burden of multivessel coronary artery disease (CAD). However, the optimal initial noninvasive test for CAD in T2DM remains unclear. This study compared coronary computed tomographic angiography (CCTA) vs. functional testing for the initial evaluation of suspected CAD in newly diagnosed T2DM. METHODS: Using data from the Korean National Health Insurance Service, we identified patients with newly diagnosed T2DM from 2007 to 2019. Among 93,152 patients, 34,694 underwent noninvasive testing for suspected CAD. After propensity score matching, 14,895 patients were included in each group. The primary outcome was a composite of acute myocardial infarction or death from CAD. Secondary outcomes included rates of invasive coronary angiography (ICA) and coronary revascularization. RESULTS: The primary outcome was lower in the CCTA group compared with the functional testing group (1.0% vs. 1.4%; adjusted hazard ratio [HR], 0.72; 95% confidence interval [CI], 0.58-0.89; p=0.002). The ICA rate was also lower in the CCTA group (10.6% vs. 16.0%; adjusted HR, 0.67; 95% CI, 0.63-0.71; p<0.001). Coronary revascularization rates were similar (5.4% vs. 6.2%; adjusted HR, 0.92; 95% CI, 0.83-1.01; p=0.069). CONCLUSIONS: In patients with newly diagnosed T2DM and suspected CAD, CCTA as an initial test was associated with better cardiovascular outcomes compared with functional testing. Although these findings cannot establish causality due to residual confounding and selection bias, they remain clinically relevant.