The aim of this study was to investigate the relationship between obesity and lower extremity arterial disease (LEAD) in patients with type 2 diabetes mellitus (T2DM). This retrospective study included 1821 patients with type 2 diabetes: 364 patients with LEAD and 1457 patients without LEAD. The patients were divided into training and internal test cohorts in a 7:3 ratio. LASSO regression analysis was used in the training cohort to filter relevant variables. Univariate and multivariate regression analyses were conducted to assess independent risk factors. A diagnostic nomogram was constructed and its discrimination was evaluated using the area under the ROC curve (AUC). The consistency was assessed using a calibration plot. The clinical application of the nomogram was evaluated by performing a decision curve analysis (DCA) and validated by an internal test cohort of the training cohorts. The LEAD group exhibited significantly higher values in obesity-related indices compared to the non-LEAD group, including waist circumference (WC), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR), conicity index (CI), body adiposity index (BAI), and abdominal volume index (AVI). Multivariate analysis identified BMI, CI, BAI, and other parameters as independent risk factors for LEAD. A nomogram was constructed, and the AUC value of the nomogram was 0.746 in the training cohort and 0.663 in the internal test cohort. Obesity-related indices are associated with LEAD in patients with T2DM. Therefore, it is important to manage waist circumference and weight to reduce the risk of LEAD in patients with T2DM.