Disturbances in vitamin D metabolism and bone turnover markers in patients with diabetes mellitus complicated by diabetic neuroosteoarthropathy (Charcot foot)

BACKGROUND: Diabetic neuroosteoarthropathy (Charcot foot) is a severe complication of diabetes mellitus, leading to foot deformity and loss of function. The pathogenesis involves disturbances in bone metabolism; however, the role of vitamin D metabolism, particularly its individual metabolites, in Charcot foot remains poorly understood.

AIM: To investigate the levels of vitamin D metabolites and their relationship with phosphate-calcium metabolism parameters and bone tissue status in patients with type 1 and type 2 diabetes mellitus complicated by Charcot foot.

MATERIALS AND METHODS: A single-center cross-sectional study was conducted, including 30 patients with Charcot foot. All participants underwent a comprehensive examination, which included assessment of a wide range of vitamin D metabolites using liquid chromatography with tandem mass spectrometry (LC-MS/MS), bone turnover markers, bone mineral density (BMD) by dual-energy X-ray absorptiometry (DXA), and evaluation of clinical and laboratory parameters.

RESULTS: Deficiency or insufficiency of 25(OH)D was detected in 64% of patients (median 17.1 ng/mL). Low levels of the active metabolite 1,25(OH)₂D₃ and the catabolite 24,25(OH)₂D₃ were observed, indicating systemic dysregulation of vitamin D metabolism. A statistically significant negative correlation was found between BMI and 3-epi-25(OH)D₃ levels (R=-0.43; p=0.041), as well as between the duration of insulin therapy and folate levels (R=-0.58; p=0.037). Patients with diabetic nephropathy had significantly higher levels of the bone resorption marker β-crosslap (p=0.003). Expected negative correlations were found between femoral neck BMD and parathyroid hormone (PTH) levels (R=-0.56; p=0.010) and albumin-corrected calcium levels (R=-0.50; p=0.016).

CONCLUSION: Patients with Charcot foot exhibit profound, multi-level disturbances in vitamin D metabolism that are universal and weakly associated with other microvascular complications. The presence of diabetic nephropathy is associated with significantly increased bone resorption. These findings justify the need for routine screening and correction of vitamin D and folate deficiencies in the comprehensive management of these patients.

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