Introduction: High body mass index (BMI) is associated with increased incidence of type 2 diabetes (T2D) and subsequent cardiovascular disease (CVD). However, the association between the BMI and the characteristics of coronary plaque in younger T2D patients with CVD remains to be elucidated. Hypothesis: Higher BMI is associated with a higher prevalence of vulnerable coronary plaque in younger T2D patients with CVD. Methods: A total of 140 consecutive younger (<65 years) T2D patients with CVD, who underwent optical coherence tomography (OCT) imaging of the culprit lesion were included. The patients were classified into either the higher BMI group (BMI ≥25.8 kg/m 2 , n=70) or the lower BMI group (BMI <25.8 kg/m 2 , n=70) according to the median of BMI. The characteristics of culprit plaque assessed by OCT were compared between the two groups. Results: The prevalence of thin-cap fibroatheroma (TCFA) (34.8 vs. 17.4%, p =0.020) and lipid-rich plaque (44.9 vs. 26.1%, p =0.021) was significantly higher in the higher BMI group than in the lower BMI group (Panel A). The prevalence of TCFA was further compared according to the tertile of LDL-C levels. A significant trend toward higher prevalence of TCFA according to the increase in LDL-C levels was observed in patients with higher BMI ( p =0.017) (Panel B), although the trend was not significant in patients with lower BMI ( p =0.487) (Panel C). Conclusions: Higher BMI was associated with a higher prevalence of TCFA in younger T2D patients with CVD. Higher LDL-C level was associated with a higher prevalence of TCFA among patients with higher BMI although the association was not significant among patients with lower BMI.