Diabetic foot ulcers are ulcers that occur in all layers of the skin accompanied by necrotic processes, which generally occur in the surface layer soles caused by neuropathy and Peripheral Arterial Disease (PAD), which is triggered by diabetes mellitus [1]. The prevalence of diabetic foot ulcers in the world in 2016 was 6.3% while in Asia, it varied at 4.6% - 6.4%. The prevalence of diabetic ulcers in Indonesia is higher than that in Asia, which is 24.43%. The percentage of diabetic ulcers in patients with type-2 diabetes mellitus was 6.4%, higher than that of patients with type-1 diabetes mellitus, which was 5.5%. PAD as a factor underlying the occurrence of diabetic ulcers is a condition that is often found in patients with diabetes mellitus. Research shows that patients with diabetes mellitus have up to a 20-fold greater risk of developing PAD. A follow-up study concluded that the risk of amputation in the first year in cases of diabetic ulcers was 34% and the risk of mortality associated with the condition was 5.5% [2]. 

The pathogenesis of diabetic foot ulcers involves various interactions between intrinsic and extrinsic factors. 

The presence of both sensory and motor neuropathy is the main intrinsic factor that underlies the occurrence of diabetic foot ulcers. Research shows that 50% of patients with type-2 diabetes mellitus are at risk for developing neuropathy. The presence of sensory neuropathy in small fibers will cause an impaired perception of pain and temperature while neuropathy in large fibers will result in proprioceptive disturbances and instability. As for motor nerve neuropathy, it will cause atrophy of the associated muscles, potentially causing a person to fall and experience repetitive trauma. Neuropathy that occurs in the autonomic nerves will result in a decrease in the precipitation process which results in dry skin so that the skin will be prone to ulceration [3]. 

Digital Subtraction Angiography (DSA) is the standard examination modality for contrast angiography in the lower extremities. This examination can scan for vascular narrowing/occlusion with contrast modalities. The presence of narrowing/stenosis in the vascular will give a picture of the obstruction of the flow of contrast in the vascular [4]. Contrast-Induced Nephropathy (CIN) is a complication of angiographic procedures and the result of administration of contrast media containing Iodine. CIN is defined as an increase in Serum Creatinine (Scr) of more than 25% or 0.5 mg/dl (44 mol/l) [5]. CIN is the third most common cause of acute kidney injury occurring in approximately 12% of cases. Ascorbic Acid or Vitamin C from various studies has a role in preventing the occurrence of CIN, and many believe this is due to the antioxidant properties of ascorbic acid. ROS-induced oxidative stress and renal vasoconstriction are thought to have a strong role in the etiology of CIN [6]. 

The purpose of this study was to determine the effect of giving Vitamin C on the incidence of CIN, which is a decrease in Glomerulus Filtration Rate (GFR) and an increase in serum creatinine in diabetic foot ulcer patients who underwent DSA. This study used a quasi-experimental design with a two-group pretest-posttest control-group design. This research was conducted in the sub-section of Cardiovascular Thoracic Surgery at dr. Moewardi General Hospital Surakarta from June to July 2021. The target population in this study were diabetic foot ulcer patients who were treated at the Cardiovascular Thoracic Surgery clinic. The research sample in this study were 20 diabetic foot ulcer patients who were treated at the Cardiovascular Thoracic Surgery clinic with DSA at dr. Moewardi General Hospital Surakarta from June to July 2021 and met the inclusion and exclusion criteria. The inclusion criteria were patients who were willing to be the subject of the study and signed informed consent, patients suffering from PAD with diabetic foot ulcers, and patients with an age range of 20-65 years and patients with good kidney function (Urea and Creatinine levels within normal limits). Exclusion criteria from this study were patients who had eGFR<60 mL/min, patients who were more than 70 years old, patients who were pregnant and breastfeeding, patients with a history of previous kidney disease, patients with a history of previous nephrectomy, patients with a history of chronic renal failure, patients with a history of heart failure, patients receiving nephrotoxic drugs such as Aminoglycosides, NSAIDs, Amphotericin B, and patients receiving vitamin C supplementation 5 days before and after the procedure. In this study, there were two treatment groups (Group A and Group B). Group A received premedication in the form of 3 g of Vitamin C injection for 24 hours before and 1 g of oral per day for 2 days after the DSA was carried out. Group B only received 100 cc of Normal Saline (NS) infusion per hour for 24 hours before and 48 hours after DSA was carried out. The data were analyzed using the Statistical Package for Social Science 25 for Windows. Data were analyzed using paired sample t-test and related-samples Wilcoxon signed-rank test. This study was approved by the ethics committee of dr. Moewardi General Hospital with ethical clearance number 571/IV/HREC/2021.

In this study, patients did not experience side effects so that no patients were dropped out. Based on Table 1, the minimum age of the subject is 35 years and the maximum is 67 years. The minimum body weight is 45 kg and the maximum is 72 kg. The average (mean) premedication urea was 44.60 mg/dL and the average post-medication was 46.50 mg/dL. The average premedication creatinine was 0.76 mg/dL and the average post-medication creatinine was 0.88 mg/dL. The average e-GFR premedication was 88.83 mL/min/1.73 m² and the average e-GFR post-medication was 80.17 mL/min/1.73 m².

The results of the Paired-sample t-test in Table 2 show the p-value of 0.014 (p<0.05) for the creatinine variable in Group B. This indicates that there is a significant difference between premedication creatinine and post-medication creatinine in Group B. The test results of related samples Wilcoxon signed-rank test in Table 3 show the p-value of 0.028 (p<0.05) for the e-GFR variable in Group B. This indicates that there is a significant difference between premedication e-GFR and post-medication e-GFR in Group B. Meanwhile, for Group A urea, Group B urea, Group A creatinine, and Group A e-GFR, there was no significant difference (p>0.05). This shows that there is a significant increase in creatinine and e-GFR in Group B, which indicates the incidence of CIN. The creatinine and e-GFR in Group A did not show a significant increase so that creatinine and e-GFR in Group A were maintained in normal conditions after vitamin C administration.

Based on Table 4, the percentage difference between group A and baseline serum creatinine was obtained. One patient had an increase in serum creatinine by 25%. This shows that one patient or 10% in Group A experienced CIN. 

Based on Table 5, the percentage difference between Group B and baseline serum creatinine was obtained. Five patients had an increase in serum creatinine by 25%. This shows that five patients or 50% in Group B experienced CIN. 

Based on Table 6, the percentage difference between Group A and the baseline e-GFR was obtained. No patients experienced a decrease in e-GFR by 25%. The average percentage increase in Group A's e-GFR was 12.57%. Based on Table 7, the percentage difference between e-GFR in Group B and baseline was obtained. Four patients or 40% experienced a decrease in e-GFR by 25%. The average percentage reduction in Group B’s e-GFR was 23.05%.

Table 1: Subject Characteristics

Table 2: Paired-Sample t-Test

Table 3: Related Samples Wilcoxon Signed-Rank Test

Table 4: Percentage Different of Creatinine Serum in Group A

Table 5: Percentage Difference of Creatinine Serum in Group B

Table 6: Percentage Difference of e-GFR in Group A

Table 7: Percentage Difference of e-GFR in Group B

CIN is an acute disorder of renal function that is manifested by an absolute increase in the serum creatinine concentration of at least 0.5 mg/dL (44.2 mol/L) or by a relative increase of at least 25% from the baseline value. The incidence of CIN is low, only about 2% of the general population. Patients with renal impairment and diabetes have a 12%-50% increased risk of developing CIN. Chronic kidney disease defined as moderate to severe with a glomerular filtration rate (eGFR) of 60 mL/min/1.73 m² is an important risk factor for the development of CIN. CIN results from direct renal tubular toxicity and renal medullary ischemia. The administration of contrast media increases the production of nephrotoxic oxygen-free radicals. Given the potential clinical severity of CIN, there is considerable interest in the development of prophylactic strategies to reduce the risk of contrast-induced renal damage in at-risk populations, such as the use of iso-osmolar contrast agents, hydration, vasodilators, and antioxidants [7]. 

Pharmacological prophylactic strategies based on antioxidant properties have received considerable attention in recent years such as studies of Ascorbic Acid and N-acetylcysteine ​​(NAC). The exact mechanism responsible for the nephroprotective action of NAC reported in several studies remains unclear. It has been suggested that protection be mediated through its antioxidant and vasodilating effects. Ascorbic acid is a safe and well-tolerated antioxidant that has been shown to reduce kidney damage caused by various disorders such as post-ischemic stress, cisplatin, aminoglycosides, and potassium bromate in animals. In addition to counteracting oxygen free radicals that mediate cell necrosis after myocardial infarction and after angioplasty, ascorbic acid can act as an antioxidant to inhibit ischemic cell death in the kidney. The results of the Randomized Control Trial (RCT) that evaluated the use of antioxidant ascorbic acid to prevent CIN in 231 patients undergoing coronary angiography were satisfactory and deserve further study [8]. 

Patients with preexisting renal impairment and diabetes have the highest risk of developing CIN. These patients are the most likely to benefit from the use of neuroprotective agents. The risk of CIN in patients with normal renal function tends to increase with the increasing complexity of endovascular interventions [9]. The pathogenesis of CIN is thought to be multifactorial with renal vasoconstriction and direct cell toxicity, both of which lead to medullary hypoxia and the production of reactive oxygen species. Coadministration of antioxidant agents may assist in managing the potential oxidative load added by radiocontrast materials. However, there was no significant difference in the incidence of CIN between N-acetylcysteine-Ascorbic Acid (NacA) and Normal saline 1000 mL (control) [10]. 

The results of this study showed a significant difference in diabetic ulcer patients suffering from CIN due to DSA between those given Vitamin C and those given normal saline. Several explanations can be given for the absence of differences between groups. Critically ill patients present with many predisposing factors for decreased renal function. In this case, it may be difficult to assess the net impact of the contrast agent on renal function. Individual cases of nephropathy occurring in critically ill patients following the use of intravenous radiocontrast material cannot be associated with certainty with contrast exposure. In this regard, the definition of CIN and the incidence of CIN varied widely between studies, i.e., 1.5-33%. In this study, the investigators included patients with stable kidneys and the definition of CIN was based on changes in serum creatinine [8]. Sang-Ho Jo et al. for the first time compared the 2 well-known antioxidants N-acetylcysteine ​​(NAC) and ascorbic acid for their relative efficacy in preventing CIN and showed that high doses of NAC were associated with less increase in SCr levels and tended to lower CIN levels than ascorbic acid [11]. 

Li Zhou and Hui Chen (2012) defined CIN with 25% or higher serum creatinine elevation 2 to 5 days after the procedure and found that ascorbic acid significantly reduced the risk of this outcome (odds ratio, 0.38; 95% CI, 0.17-0.85). However, this study did not show a significant benefit of ascorbic acid in CIN prophylaxis. In the study of Li Zhou and Hui Chen [12], some mild CKD patients were enrolled, and all patients received adequate hydration, so the incidence of CIN was lower than reported. Both the bioavailability and maintenance time of oral and intravenous ascorbic acid are not the same. Large doses of short-term application of ascorbic acid can affect the effective intake of the human body. Ascorbic acid affects the role of antioxidants in kidney function. We conclude that short-term application of high-dose ascorbic acid does not prevent impaired renal function following contrast media administration in patients with early renal insufficiency undergoing coronary angiography. Therefore, large sample studies may be needed to verify the benefits of ascorbic acid in CIN [12]. Another thing that can be noted to help explain the absence of differences between N-acetylcysteine ​​and Ascorbic acid (NacA) and controls is that there are indications that the control group included fewer patients with diabetes mellitus, patients given NacA received higher volumes of radiocontrast material, or control patients received more fluids on the day before and on the day on which the radiocontrast material was given. These factors may have obscured the significant prophylactic impact of antioxidant agents on renal function [13]. 

Khaledifar et al. [13] conducted a study using a combination of antioxidant agents, N-acetylcysteine ​​(Nac), and Ascorbic acid (Aa). The results of this study failed to reduce the incidence of CIN in critically ill patients undergoing CT with radiocontrast material. This study suggests that an increase in the urea/creatinine ratio and the use of nephrotoxic drugs, particularly colimycin, may adversely affect renal function in this setting. Despite the absence of a significant impact of Nac-Aa in the incidence of CIN, the use of antioxidants partially balances the burden of oxidative stress after contrast infusion and decreases renal injury in patients with CIN. The results of this study should be validated in a large number of patients in future multicenter randomized clinical trials [13].

A recent trial compared 3 regimens for the prevention of CIN, namely 0.9% saline plus NAC, sodium bicarbonate plus NAC, and 0.9% saline plus ascorbic acid plus NAC. The results of this study indicate that the use of sodium bicarbonate plus NAC appears to be superior to other measures. The authors state that there is a less protective effect of ascorbic acid plus NAC compared to NAC alone because NAC and ascorbic acid can act via the same pathway [6] Therefore, it is very important to determine which antioxidant is more powerful and beneficial to prevent the occurrence of CIN. We consider that future studies need to be carried out in a larger population with long-term follow-up.

Vitamin C can maintain serum creatinine and GFR in normal conditions. This indicates that Vitamin C can prevent the occurrence of CIN.

Acknowledgment

The authors of this case report would like to thank Department of Surgery Dr. Moewardi General Hospital Surakarta for providing support and information for this study.

Conflict of Interest

No potential conflict of interest relevant to this study was reported.

1. Alavi, A. et al. “Diabetic foot ulcers: Part I. pathophysiology and prevention.” Journal of the American Academy of Dermatology, 2014, https://doi.org/10.1016/j.jaad.2013.06.055.

2. Chun, D. et al. “Epidemiology and burden of diabetic foot ulcer and peripheral arterial disease in Korea.” Journal of Clinical Medicine, vol. 8, no. 5, 2019, pp. 748, https://doi.org/10.3390/jcm8050748.

3. Armstrong, D. G. et al. “Diabetic foot ulcers and their recurrence.” New England Journal of Medicine, 2017, https://doi.org/10.1056/NEJMra1615439.

4. Pomposelli, F. “Arterial imaging in patients with lower extremity ischemia and diabetes mellitus.” Journal of Vascular Surgery, 2010, https://doi.org/10.1016/j.jvs.2010.06.013.

5. Ilkhchooyi, F. et al. “The efficacy of hydration with normal saline versus hydration with sodium bicarbonate in the prevention of contrast-induced nephropathy.” Heart Views, 2014, https://doi.org/10.4103/1995-705x.137489.

6. Sadat, U. et al. “Does ascorbic acid protect against contrast-induced acute kidney injury in patients undergoing coronary angiography: A systematic review with meta-analysis of randomized controlled trials.” Journal of the American College of Cardiology, vol. 62, no. 23, 2013, pp. 2167–2175, https://doi.org/10.1016/j.jacc.2013.07.065.

7. Rear, R. et al. “Contrast-induced nephropathy following angiography and cardiac interventions.” Heart, vol. 102, no. 8, 2016, pp. 638–648, https://doi.org/10.1136/heartjnl-2014-306962.

8. Palli, E. et al. “The impact of n-acetylcysteine and ascorbic acid in contrast-induced nephropathy in critical care patients: An open-label randomized controlled study.” Critical Care, https://doi.org/10.1186/s13054-017-1862-3.

9. Wijaya, A. T. and B. Atmadja. “Identifikasi risiko dan pencegahan terhadap nefropati akibat kontras.” Jurnal Radiologi Indonesia, 2016, https://doi.org/10.33748/jradidn.v2i1.50.

10. Essentials, P. Contrast-Induced Nephropathy. 2017.

11. Jo, S. et al. “N-acetylcysteine versus ascorbic acid for preventing contrast-induced nephropathy in patients with renal insufficiency undergoing coronary angiography.” American Heart Journal, vol. 157, no. 3, pp. 576–583, https://doi.org/10.1016/j.ahj.2008.11.010.

12. Zhou, L. and H. Chen. “Prevention of contrast-induced nephropathy with ascorbic acid.” Internal Medicine, vol. 51, no. 6, 2012, pp. 531–535, https://doi.org/10.2169/internalmedicine.51.6260.

13. Khaledifar, A. et al. “Comparison of n-acetylcysteine, ascorbic acid, and normal saline effect in prevention of contrast-induced nephropathy.” ARYA Atherosclerosis, vol. 11, no. 4, 2015.