Diabetic foot ulcers (DFUs) represent one of the most serious and costly complications of diabetes mellitus, affecting approximately 15–25% of patients with diabetes over their lifetime. These chronic wounds not only diminish quality of life but also frequently lead to infections, osteomyelitis, and lower-extremity amputations. While glucose control, peripheral neuropathy, and vascular insufficiency are well-established risk factors, emerging evidence points to a less obvious but equally critical player: iron balance. The body's regulation of iron—a micronutrient essential for oxygen transport, DNA synthesis, and cellular metabolism—appears to exert a profound influence on the pathogenesis and resolution of DFUs. This article examines the dual-edged nature of iron in wound healing, explores the mechanisms by which both deficiency and overload can impair tissue repair, and outlines practical strategies for optimising iron status to improve clinical outcomes.

Understanding the interplay between iron homeostasis and diabetic foot ulceration is not merely an academic exercise; it offers a tangible opportunity to refine treatment protocols and reduce the burden of disease. As we delve into the physiology of iron storage, transport, and utilisation, it becomes clear that maintaining a tight equilibrium is essential. Disruption in either direction—too little or too much iron—can set off a cascade of cellular events that frustrate the body's ability to close a wound, control infection, and regenerate healthy tissue.

The Physiology of Iron Homeostasis

Iron is a double-edged sword in human biology. On one hand, it is indispensable for erythropoiesis, mitochondrial respiration, and enzymatic reactions. On the other hand, free iron is highly reactive and can catalyse the formation of reactive oxygen species (ROS) through Fenton chemistry. To contain these risks, the body has evolved sophisticated regulatory mechanisms involving proteins such as ferritin (the storage form), transferrin (the transport protein), and hepcidin (the master hormonal regulator). Most iron is recycled from senescent red blood cells by macrophages in the spleen and liver, with only a small fraction absorbed from the diet each day.

In healthy individuals, serum ferritin levels typically range from 20 to 300 ng/mL in men and 20 to 200 ng/mL in women, reflecting total body iron stores. Transferrin saturation—the percentage of iron-binding sites occupied—usually falls between 20% and 45%. When these parameters stray outside normal limits, the risk of cellular dysfunction rises. The liver serves as the primary sensor of systemic iron status, and in response to iron overload it secretes hepcidin, which degrades the iron export channel ferroportin on enterocytes and macrophages, thereby reducing iron absorption and release. Conversely, anaemia or hypoxia suppresses hepcidin to facilitate iron mobilisation. This elegant system normally maintains balance, but chronic inflammatory states—common in diabetes—can disrupt it. Inflammatory cytokines such as interleukin-6 upregulate hepcidin, leading to functional iron deficiency (low serum iron but adequate stores) and contributing to the anaemia of chronic disease.

For patients with diabetic foot ulcers, the inflammatory milieu is particularly relevant. The wound itself generates a sustained local and systemic inflammatory response that can alter iron trafficking. Macrophages at the wound site need iron for antimicrobial activity and to support the proliferative phase of healing, yet excess iron in the microenvironment can fuel oxidative damage to fibroblasts and endothelial cells. Understanding these nuances is critical for clinicians aiming to use iron as a modifiable factor in wound care.

Iron Deficiency and Impaired Wound Healing

Mechanisms of Iron Deficiency in DFU Patients

Iron deficiency is a common comorbidity in the diabetic population, often stemming from multiple causes. Poor dietary intake, gastrointestinal malabsorption due to autonomic neuropathy, and the use of medications such as metformin (which can interfere with vitamin B12 and aggravate anaemia) all contribute. Additionally, chronic blood loss from gastritis, ulcerations, or haemorrhoidal disease may go unnoticed but can deplete iron stores over time. In the context of a diabetic foot ulcer, the persistent drainage of exudate can also result in the loss of plasma proteins and trace elements, including iron.

The hallmark of iron deficiency is anaemia—a reduction in red blood cell mass that impairs oxygen delivery to peripheral tissues. Because wound healing is an energy-intensive, oxygen-dependent process, even mild anaemia can significantly delay closure. Without an adequate supply of oxygen, fibroblasts cannot synthesise collagen efficiently, angiogenesis stalls, and keratinocyte migration slows. Experimental studies have demonstrated that iron-deficient animals exhibit poorer wound tensile strength and slower epithelialisation compared to controls. Clinical evidence in humans is more limited but consistent: diabetic patients with anaemia have a higher incidence of non-healing ulcers and a greater risk of major amputation.

Diagnosis and Clinical Implications

Detecting iron deficiency in DFU patients requires a careful assessment beyond haemoglobin levels. Serum ferritin, transferrin saturation, and soluble transferrin receptor (sTfR) are more sensitive indicators of iron status, particularly when inflammation is present. A ferritin level below 30 ng/mL reliably indicates depleted stores, while values between 30 and 100 ng/mL in the setting of inflammation may still represent functional deficiency. Since hepcidin is often elevated in diabetes, interpreting iron parameters can be challenging. The use of reticulocyte haemoglobin content (CHr) and the ratio of hepcidin to ferritin is gaining traction as a more precise tool.

For patients confirmed to have iron deficiency, supplementation is warranted. Oral iron (e.g., ferrous sulfate 65 mg elemental iron daily) is the first-line approach, though gastrointestinal side effects and reduced absorption due to concurrent inflammation can limit efficacy. In such cases, intravenous iron preparations (iron sucrose, ferric carboxymaltose) offer a rapid and well-tolerated alternative, especially when a timely improvement in healing is desired. However, caution is necessary: in the presence of infection, iron supplementation may potentially enhance pathogen growth, as many bacteria rely on iron for proliferation. Therefore, iron therapy should be guided by microbiological and clinical context, ideally after controlling active infection through debridement and antibiotics.

Iron Overload: Oxidative Stress and Inflammation

Pathophysiology of Excess Iron in DFU

Iron overload, whether due to hereditary hemochromatosis, repeated transfusions, excessive supplementation, or chronic inflammation leading to redistribution (the anaemia of chronic disease can also cause iron sequestration), presents a different but equally harmful scenario for DFU patients. In iron overload, the protective binding capacity of transferrin becomes saturated, and non-transferrin-bound iron (NTBI) appears in the circulation. This labile iron species readily enters cells and catalyses the production of hydroxyl radicals, causing lipid peroxidation, protein damage, and DNA fragmentation. The resultant oxidative stress impairs the function of endothelial progenitor cells, reduces nitric oxide bioavailability, and promotes a pro-inflammatory state that is antithetical to healing.

Elevated iron levels have been shown to inhibit keratinocyte migration and re-epithelialisation in in vitro models. Furthermore, iron overload is associated with increased expression of matrix metalloproteinases (MMPs), enzymes that degrade the extracellular matrix. While a controlled level of MMP activity is necessary for wound debridement, excess MMP activity leads to chronic wound progression and failure to progress into the proliferative phase. Diabetic foot ulcers are notoriously high in MMPs, and iron overload may exacerbate this imbalance.

Clinical Evidence and Hemochromatosis

The relationship between hereditary hemochromatosis and diabetic foot ulcers is under-studied, but the existing data are compelling. Hemochromatosis, a genetic disorder of iron hyperabsorption, leads to progressive iron deposition in organs including the pancreas, liver, and skin. It is associated with a higher prevalence of diabetes (so-called "bronze diabetes") and with peripheral microvascular complications. Case reports have documented non-healing foot ulcers in hemochromatosis patients that resolved only after iron depletion therapy (phlebotomy). In the broader diabetic population, epidemiological studies have found that elevated serum ferritin is a predictor of incident foot ulcers and poor healing outcomes, independent of other risk factors.

One study published in Diabetes Care (external link: Association between ferritin and diabetic foot ulcers) demonstrated that patients with DFU had significantly higher ferritin levels than diabetic controls, and that ferritin correlated positively with ulcer severity and duration. Another investigation in Wound Repair and Regeneration (external link: Iron overload impairs wound healing in diabetic mice) reported that phlebotomy improved wound closure rates in a diabetic mouse model. Although human trials of iron reduction therapy for DFU are lacking, these findings suggest that limiting iron stores—through phlebotomy or chelation—could be beneficial for patients with evidence of overload.

Diagnostic Strategies and Clinical Monitoring

Key Laboratory Assessments

Given the potential impact of iron imbalance on DFU outcomes, routine evaluation of iron status should be considered part of comprehensive wound care. The American Diabetes Association (external link: Standards of Care in Diabetes) recommends periodic assessment of haemoglobin and haematocrit, but specific iron indices are not always standard. A reasonable panel includes:

  • Serum ferritin – reflects total iron stores; low (< 30 ng/mL) indicates deficiency; high (> 300 ng/mL in men, > 200 in women) suggests overload or inflammation.
  • Transferrin saturation – calculated as (serum iron / total iron-binding capacity) × 100; < 20% suggests deficiency, > 45% suggests overload.
  • C-reactive protein (CRP) – to adjust for the acute-phase effect on ferritin; a normal CRP with high ferritin indicates true overload.
  • Complete blood count – to detect anaemia (Hb < 13 g/dL in men, < 12 g/dL in women) and examine red cell indices (MCV, MCH) for microcytosis typical of iron deficiency.

Serial monitoring every 3–6 months is advisable for patients with DFU, especially those undergoing treatment that affects iron (e.g., supplementation, transfusions, or chelation).

Clinical Management of Iron Status in DFU Patients

Correcting Iron Deficiency

For patients with confirmed iron deficiency and anaemia, the goal is to replenish stores without overshooting. Oral iron is the safest initial option, though its absorption is limited by hepcidin-related blockade in inflammation. Co-administration with vitamin C (e.g., 200 mg) may enhance absorption, but the clinical benefit is modest. If oral iron fails to raise haemoglobin by 1 g/dL within 4 weeks, intravenous iron should be considered. Ferric carboxymaltose is particularly useful as it allows a full repletion dose in a single infusion and has a low risk of hypersensitivity. Importantly, iron therapy should be stopped once ferritin reaches 100 ng/mL to avoid sliding into overload. In patients with DFU who have active infection, deferring iron supplementation until infection is controlled may be prudent, as iron can fuel bacterial growth. However, severe anaemia (Hb < 7 g/dL) warrants immediate treatment regardless of infection.

Managing Iron Overload

When iron overload is identified (e.g., ferritin > 300 ng/mL with transferrin saturation > 45% and normal CRP), the underlying cause must be addressed. Hereditary hemochromatosis requires genetic testing for the C282Y mutation. If confirmed, therapeutic phlebotomy—removing 500 mL of blood weekly until ferritin falls below 50 ng/mL—is the standard of care. For patients who cannot tolerate phlebotomy (e.g., those with anaemia of chronic disease or severe cardiovascular instability), oral iron chelators such as deferasirox or deferiprone can be used, though they have significant side effects and drug interactions. In the diabetic population with overload secondary to inflammation (so-called "dysmetabolic iron overload syndrome"), weight loss, exercise, and control of insulin resistance often improve ferritin levels. Some studies (external link: Reducing iron stores in type 2 diabetes) suggest that regular phlebotomy may improve insulin sensitivity and reduce cardiovascular risk, which could secondarily benefit wound healing.

Dietary Considerations

Dietary iron management should be individualised. For deficiency, iron-rich foods (red meat, spinach, legumes) and enhancers (vitamin C) are recommended. For overload, reducing intake of haem iron (red meat) and avoiding iron-fortified cereals and supplements is sensible. The role of iron in the diet of DFU patients is often overlooked; a registered dietitian can help tailor advice. Additionally, because diabetes itself is a pro-inflammatory state that upregulates hepcidin, a diet low in pro-inflammatory components (refined carbohydrates, saturated fat) may indirectly improve iron distribution and reduce functional deficiency.

Emerging Research and Future Directions

The role of iron in diabetic wound healing is an active area of investigation. Novel therapeutic approaches being explored include the use of iron-chelating agents applied topically to wounds to reduce local oxidative stress without affecting systemic iron stores. Preliminary studies in animal models have shown that topical deferoxamine can improve angiogenesis and accelerate closure. Human trials are needed to confirm efficacy and safety. Another avenue is the modulation of hepcidin expression; hepcidin antagonists could potentially increase iron availability to the wound while preventing systemic overload. However, these drugs are still in early development.

Furthermore, the use of biomarkers such as hepcidin/ferritin ratio and NTBI may allow more precise identification of patients who would benefit from iron manipulation. The integration of iron management into standard DFU protocols could represent a low-cost, high-impact intervention. Clinicians are encouraged to stay updated with guidelines from organisations such as the Wound Healing Society (external link: WHS guidelines for diabetic foot ulcers) and the International Working Group on the Diabetic Foot (external link: IWGDF guidelines), which increasingly acknowledge the importance of nutritional and metabolic optimisation.

Conclusion

Iron balance is a critical, yet frequently underappreciated, factor in the pathogenesis and healing of diabetic foot ulcers. Both iron deficiency and iron overload create a hostile environment for tissue repair—the former by starving cells of oxygen and the latter by flooding them with oxidative stress. The clinical takeaway is clear: routine assessment of iron status in DFU patients can uncover modifiable abnormalities. Correcting deficiency with targeted supplementation or reducing overload through phlebotomy or chelation may improve wound healing trajectories, reduce the risk of amputation, and enhance patient outcomes. As the evidence base grows, integrating iron management into multidisciplinary DFU care promises to be a straightforward, cost-effective addition to the therapeutic arsenal. The challenge now lies in raising awareness among clinicians, standardising diagnostic protocols, and conducting the rigorous clinical trials needed to translate bench findings into bed—and bedside—practice.