Background It was recently reported that thin‐cap fibroatheroma (TCFA) detected by optical coherence tomography was an independent predictor of future cardiac events in patients with diabetes. However, the clinical usefulness of this finding is limited by the invasive nature of optical coherence tomography. Computed tomography angiography (CTA) characteristics of TCFA have not been systematically studied. The aim of this study was to investigate CTA characteristics of TCFA in patients with diabetes. Methods and Results Patients with diabetes who underwent preintervention CTA and optical coherence tomography were included. Qualitative and quantitative analyses were performed for plaques on CTA. TCFA was assessed by optical coherence tomography. Among 366 plaques in 145 patients with diabetes, 111 plaques had TCFA. The prevalence of positive remodeling (74.8% versus 50.6%, P <0.001), low attenuation plaque (63.1% versus 33.7%, P <0.001), napkin‐ring sign (32.4% versus 11.0%, P <0.001), and spotty calcification (55.0% versus 34.9%, P <0.001) was significantly higher in TCFA than in non‐TCFA. Low‐density noncalcified plaque volume (25.4 versus 15.7 mm ³ , P <0.001) and remodeling index (1.30 versus 1.20, P =0.002) were higher in TCFA than in non‐TCFA. The presence of napkin‐ring sign, spotty calcification, high low‐density noncalcified plaque volume, and high remodeling index were independent predictors of TCFA. When all 4 predictors were present, the probability of TCFA increased to 82.4%. Conclusions The combined qualitative and quantitative plaque analysis of CTA may be helpful in identifying TCFA in patients with diabetes. Registration Information URL: https://www.clinicaltrials.gov ; Unique identifier: NCT04523194.