Association Between Diabetes-Related Lower-Extremity Amputations and Renal Function: An Observational, Single-Center,...

The prevalence of lower-extremity amputation (LEA) in diabetic foot ulcer (DFU) patients has been well documented. Diabetic nephropathy is one of the major complications of diabetes. However, little is known about a potential relationship between renal function and LEA in DFU patients with renal insufficiency. This study aimed to examine the association between LEA and renal function in DFU patients with renal insufficiency, focusing on the changes of the estimated glomerular filtration rate (eGFR) and associated inflammatory markers pre- and postamputation.

A retrospective cohort study analyzed 240 patients with DFU between 2020 and 2023 at a single university center for treating diabetic foot. Patients were categorized into five groups based on baseline eGFR and into three groups according to postamputation changes in eGFR (improvement, stability, and deterioration). Univariate and multivariate logistic regression analyses were conducted to identify predictors of renal function changes following amputation. Key inflammatory markers evaluated included white blood cell count, neutrophil count, neutrophil percentage, neutrophil-to-lymphocyte ratio, and C-reactive protein (CRP).

Lower baseline eGFR was associated with a higher risk of major amputation and more severe DFU. Postamputation, 66.2% of patients exhibited improved eGFR, with reductions in serum creatinine, blood urea nitrogen, cystatin C, and inflammatory markers such as CRP. Multivariate analysis identified Δ CRP as an independent protective factor for renal function changes after LEA.

LEA in patients with DFU, particularly those with renal insufficiency, may improve renal function postamputation, likely due to reduced systemic inflammation. Monitoring levels of CRP and other inflammatory markers levels pre- and postamputation could help predict renal function changes following amputation.