Diabetic nephropathy and diabetic foot syndrome (DFS) are two major complications of diabetes. Surprisingly, little is known of a potential relationship between renal function and the development of DFS in patients with preterminal renal insufficiency. A retrospective cohort study at a single tertiary university centre caring for a large collective of patients with type 1 and 2 diabetes was performed.Patients and methods
All patients with type 1 or 2 diabetes from 1989 to 2007 on the electronic patient sheet who had standardized food examination, albuminuria and serum creatinine were analysed. A total number of 899 patients with type 1 and 4007 individuals with type 2 diabetes were studied. Estimated glomerular filtration rate (eGFR) was calculated according to the modified equation 7 MDRD formula. Patients were grouped into the chronic kidney disease (CKD) stages according to the eGFR and presence of albuminuria. DFS was classified according to Wagner as well as Armstrong stages.Results
Forty-six patients (5.1%) of 899 patients with type 1 diabetes have active or a history of DFS. Patients with type 1 diabetes and DSF had significantly higher serum creatinine levels, lower eGFR, higher systolic blood pressure and higher HbA1c levels compared to those without DFS. There was a significant negative correlation between eGFR and the presence of DFS in patients with type 1 diabetes (r=−0.155, P < 0.01). In type 1 diabetes patients, there was a significant negative correlation (Spearman test) between eGFR and Wagner stages (r=−0.218, P=0.01) as well as Armstrong stages (r=−0.255, P=0.01). Multiple logistic regression analysis revealed a significant association between the presence of DFS and eGFR (odds ratio 0.696 per 10 ml/min increase, 95% confidence interval 0.627–0.773, P < 0.001). A total of 532 type 2 patients from 4007 patients had DFS (13.7%). Compared with type 2 patients without DFS, those with DFS were significantly older (P < 0.005), exhibited a higher HbA1c, had a longer duration of diabetes (P < 0.005), higher serum creatinine levels (P < 0.005) and a lower eGFR (P < 0.005). There was a significant negative correlation between the Wagner stages and eGFR (r=−0.104, P < 0.01) as well as Armstrong stages and eGFR (r=−0.125, P < 0.01) in all patients with type 2 diabetes (Spearman test). Multiple logistic regression analysis revealed a significant association between the presence of DFS and eGFR (odds ratio 0.873 per 10 ml/min increase, 95% confidence interval 0.842–0.904, P < 0.001). There were also significant associations between DFS and duration of diabetes as well as diastolic blood pressure. In addition, the Jonckheere–Terpstra test confirmed the decrease of eGFR with increasing Wagner and Armstrong stages in patients with type 2 diabetes. Smoking was not associated with a higher prevalence of DFS in type 1 and 2 diabetic patients.Conclusion
There was a strong association between the degree of renal function impairment and DFS in this observational study. Data show that diabetics with DFS undergo a higher incidence of amputation; thus, it should be recommended that diabetic patients with renal insufficiency should be regularly screened for the presence of DFS.