First, the elevated serum creatinine reflects declining renal filtration capacity, leading to systemic accumulation of uremic toxins linked to diabetic nephropathy-foot ulcer comorbidity [30,31], the impaired toxin clearance amplifies TLR4/NF-κB signaling in dermal fibroblasts, increasing MMP-9 production and collagen degradation [32]. This evidence concerns the gene MMP9 and diabetic kidney disease.