Abstract
BACKGROUND: The aim of this study was to investigate the associations of blood phosphorus levels with the risk of developing medial arterial calcification (MAC) in lower-limb arteries and diabetic foot (DF) in diabetes patients. We sought to enhance the understanding of the pathophysiology of diabetic complications and develop strategies to mitigate diabetes-related risks. METHODS: We conducted a retrospective analysis of 701 diabetic patients from the Department of Endocrinology at Sun Yat-Sen Memorial Hospital (2019-2023). We utilized multimodel-adjusted logistic regression to investigate the associations of serum phosphorus levels and the risk of developing MAC and DF. Restricted cubic spline plots were employed to model the relationships, and threshold analysis was used to identify inflection points. Subgroup analyses were performed to explore variations across different demographics. The diagnostic utility of phosphorus concentrations was assessed via the C index, net reclassification improvement (NRI), and integrated discrimination improvement (IDI). RESULTS: Of the 701 patients (mean age 63.9 years; 401 (57.20%) were male), 333 (47.50%) had MAC, and 329 (46.93%) had DF. After controlling for numerous confounding variables, each one-unit increase in phosphorus concentrations was associated with an increased risk of developing MAC (OR 2.65, 95% CI 1.97-3.57, p < 0.001) and DF (OR 1.54, 95% CI 1.09-2.18, p = 0.014). Phosphorus levels demonstrated a linear risk association, with risk not being uniform on either side of the inflection point, which was approximately 3.28 mg/dL for MAC and varied for DF (3.26 to 3.81 mg/dL). Adding the phosphorus as an independent component to the diagnostic model for MAC and DF increased the C index, NRI, and IDI to varying degrees. CONCLUSIONS: Elevated serum phosphorus levels are significantly associated with an increased risk of developing MAC and DF among diabetic people. These findings suggest that phosphorus management could be integrated into routine diagnostic processes to improve the identification and management of lower-extremity diabetic complications.