Development of a machine learning-based classification model for diabetic foot in patients with type 2 diabetes: an exploratory analysis with SHAP interpretation.

Background: Diabetic foot (DF) is one of the most severe complications of type 2 diabetes mellitus (T2DM), contributing to over 85% of diabetes-related lower limb amputations and a 5-year mortality rate comparable to certain cancers. Current diagnostic approaches face challenges including over-reliance on single-indicator screening, limited multimodal data integration, and lack of model interpretability. Methods: A dataset integrating five modalities-sociodemographic characteristics, physiological indicators, traditional Chinese medicine (TCM) tongue features, plantar hardness metrics, and laboratory biomarkers-was prospectively collected from 391 patients (124 T2DM, 267 DF) at a single tertiary hospital between May 2019 and October 2022. The final model was constructed using 18 clinical features from sociodemographic, physiological, and laboratory modalities. Seven machine learning algorithms were developed and compared, and SHapley Additive exPlanations (SHAP) were used for interpretability analysis. Results: LightGBM achieved optimal performance (accuracy: 88.61%, sensitivity: 87.76%, specificity: 90.00%, AUC: 0.9519). Key classification features included age, body mass index (BMI), creatinine (Cr), white blood cell count (WBC), and uric acid (UA). Discussion: These features reflect general systemic inflammation, metabolic burden, and renal function rather than DF-specific pathology. The study contributes (1) an open-source multimodal DF dataset bridging TCM and Western medicine, (2) a classification tool that distinguishes DF from uncomplicated T2DM with reasonable accuracy as a potential supplementary screening instrument pending external validation, and (3) novel mechanistic insights suggesting that systemic inflammatory markers may play an important role in DF pathophysiology.