Objective: Cystatin C (CysC) is growing to be an ideal indicator for renal function and cardiovascular events. The aim of this study was to investigate the relationship between serum Cystatin C levels and the prognosis of diabetic foot (DF).

　　 　　 Methods: In total, 1072 patients with type 2 diabetes were recruited and divided into two groups: non-diabetic-foot group (NDF, n=865, 80.39%); diabetic foot group (DF, n=207,19.3%; consist of non-ulcer diabetic foot group (NUDF, n=60, 29%) and diabetic foot ulcer group (DFU, n=147, 71%). After 1 year follow-up, all of the diabetic foot patients were grouped into non-healing group (n=45, 21.7%) and healing group (n=162, 78.3%), according to the clinical prognosis. Clinical characteristics and the impact factors of ulcer healing were compared and analyzed.

　　 　　 Results: Serum CysC levels were significantly higher in patients complicated with DF than that without DF (P<0.05). Compared to the cured group, non-healing group had significantly higher serum Cys C concentrations in both NUDF group and DFU group (P<0.01). The patients were divided into quartiles according to serum CysC levels. Compared with quartile 1 (referent), the risk of DF non-healing rate (OR=10.061, 95% CI: 2.249-45.01, P<0.003) was significantly higher in quartile 4. Logistical regression analysis further revealed that CysC was an independent impact factor for DF non-healing rate (β=1.248) and DFU non-healing rate (β=1.081) (both P<0.01). After adjusting for all potential confounders, CysC was still associated with increased risk of DF non-healing rate (OR=3.318, 95% CI: 1.605-6.857, P<0.01) and DFU non-healing rate (OR=2.841, 95% CI: 1.343-6.009, P1.2 mg/L suggested the poor prognosis of foot disease.

　　 　　 Conclusions: There is a strong and independent association between CysC and diabetic foot prognosis, and CysC >1.2 mg/L hints 2-fold increased risk of incurable ulceration for DF.