Foot Infection in Diabetes

  • 1st Revision: Isobel Lester
  • 2nd Revision: Conor Hodges
  • 3rd Revision: Pranitha Ven MuraliLinkedin

Diabetic foot infection refers to infections in the bone and/or soft tissue of the foot. It is a common consequence and physical manifestation of diabetes mellitus. It can lead to various complications that range from hospitalisation to amputation. The infections may be mild, moderate, or severe, and are caused by a variety of pathogens (bacteria, fungi, virus), with staph infections (caused by the bacteria Staphylococcus) being the most common form. A complication of diabetic foot infection is osteomyelitis (chronic pain due to infection), which increases the need for surgery to treat the infection. However, mild infections are easier to treat and usually take place in an out-patient clinical setting. For individuals with mild to moderate infections, hospitalisation is likely, and the treatment plan is based on a variety of subjective factors. Peripheral arterial disease is a common contributor to increased likelihood of getting a diabetic foot infection. Preventive measures include regular check-ups, lifestyle changes, appropriate footwear, health education, and evaluations for surgical infections. 

How can diabetes affect the feet?

Diabetes involves an unmoderated change in the level of blood sugar in the body. This damages the blood vessels that transport the blood sugar, and over time this prevents them from supplying vital nutrients to the nerves. As a result,  the nerves are damaged and their functioning is impaired. Impaired function prevents feeling sensations of touch, pain, pressure and temperature, meaning that injuries such as cuts, scrapes, bruises, abrasions, or blisters cannot be felt. The lack of sensation due to nerve damage is referred to as sensory diabetic neuropathy. These minor problems could amount to ulcers or sores due to a buildup of bacteria in these vulnerable places.

Harmful bacteria can use these areas as breeding grounds, as they provide access into the body through the skin. This can turn into a larger infection and damage the cells in that area, eventually causing cell death, also known as tissue necrosis. Additionally, nerve and blood vessel damage can also prevent these infections from healing. This is attributed to problems with neutrophil (a type of white blood cell associated with immunity) and a weakened defence mechanism.

The likelihood of getting a foot infection as a result of diabetes depends on certain factors, such as peripheral neuropathy, peripheral arterial disease, and impaired immunity. 

Peripheral neuropathy is caused by chronically high blood sugar. It is a form of nerve damage that  can lead to the formation of neuropathic ulcers, which may lead to further infection and other complications.

Peripheral arterial disease is a problem that affects blood circulation and heart health. Poor blood circulation can lead to ischemic ulcers. 

The possibility of neuro-ischemic ulcer formation is also high, since higher blood sugar damages both nerve and blood vessel function, reducing the body’s ability to repair itself. Ulcers can also be caused by plaque build-ups in blood vessels, known as atherosclerosis.This reduces blood flow to extremities, and can speed up the development of diabetic foot infections.

Most diabetic foot infections are marked with the onset of foot ulcers. However, it is possible for an infection to naturally develop, causing cellulitis and necrotising fasciitis. 

Cellulitis refers to when the skin turns hot, red, and swollen with blisters. Its onset is associated with the presence of bacteria. Necrotizing fasciitis (NF) is a severe form of soft-tissue infection that leads to cell injury and cell death. It causes skin to die and blood clots to form. It provides the potential for the development of bacteraemia and sepsis. This is a fast-growing form of the infection and can damage overall organ function and possibly lead to organ failure, especially in the case of sepsis. 

Signs of diabetic foot infections 

Diabetic foot infections are progressive diseases that can develop over a period of time, or rapidly if left untreated. Therefore, it is important to look for the signs of diabetic foot infections.

  • Redness is a primary sign of infection, especially if it surrounds a wound. This is a local inflammatory response of the skin, and it might be a sign of a bacterial infection that the body is trying to fight. Plantar warts are like calluses on the heel. They appear as dark pigments and are usually painful. They are caused by infection from a virus affecting the soles of the feet
  • Darkened skin on the affected area
  • Diminished ability to sense hot or cold 
  • Loss of hair in the area 
  • Fever
  • Numbness
  • Tingling
  • Any changes to the skin or toenails, including cuts, blisters, calluses or sores
  • Discharge of fluid or pus. Continuous blood discharge in the pus is indicative of a serious problem
  • Foul smell attributable to pus or fungal infections
  • Skin discoloration
  • Swelling 
  • Other symptoms of inflammation such as warmth, tenderness, pain, or induration 

What is the treatment plan for diabetic foot disease?

The type of treatment plan depends on whether the infection is mild, moderate, or severe:

  • The first line of local treatment involves cleaning or debridement of the wound. Removing infected tissue, pathogens, and contaminants is vital for the wound to get better. 
  • Maintaining a sterile environment around the wound and using clean bandages is  key, since the wounded area is highly susceptible to infection. 
  • The first line of systemic treatment uses oral antibiotics  for up to three weeks. 
  • Moderate infections are primarily treated with oral antibiotics or IV antibiotics.
  • Severe infections may require hospitalisation and constant monitoring as well as a course of antibiotics
  • In severe cases, the decision of a limb amputation may be considered.

How can I prevent diabetes foot infections?

Diabetes-associated foot infections are caused by many factors, the presence of which can also increase the severity of the infection. Therefore, it is vital to keep in mind the preventive measures that could help reduce the likelihood of contracting these infections:

  • Exercise can help to reduce your risk of  foot infections. These include vascular diseases such as peripheral arterial disease, atherosclerosis, and other vascular disorders. It can also help to improve overall blood circulation.
  • Changes in dietary habits are a factor of importance. High cholesterol increases the likelihood of vascular diseases which may contribute to ischemic ulcers. Additionally, quitting smoking and reducing alcohol consumption  also helps to prevent tissue damage.
  • Prescription footwear can also be a vital preventive measure. In cases of neuropathy, tissue damage may go unnoticed. Damage to the skin can leave underlying tissue exposed and vulnerable to infections. Prescription shoes can prevent injuries by easing the pressure placed on soles of the feet.
  • Practising good foot hygiene may help you spot any abnormalities early. 

What are the potential complications of diabetic foot infections?

Foot wounds in diabetic patients have to be monitored as they can progress into certain clinical complications. If a foot wound is left untreated, the risk of infection increases. Some common complications are:


Gangrene is a serious condition where blood supply to tissues is lost and tissues begin to die. It can affect any part of the body, but generally starts in the feet and toes. Gangrene can spread rapidly through the deeper layers in the skin and connective tissue, eventually causing organ failure due to injury and damage. 


Ulceration is caused in diabetics with poor blood circulation, unregulated and unmonitored diabetes, and massive fluctuations in blood glucose levels.

  • Corns and calluses are hardenings of skin that, if left untreated, can develop into ulcers.
  • Charcot arthropathy or Charcot foot is a complex foot deformity that develops as a result of bone fractures. This increases pressure on the tissue and muscle in the area of the broken bone, which leads to the destruction of soft tissue in the bone. This complication is so severe that surgery, and occasionally amputation, may be necessary.
  • Amputations are considered in cases where there is no salvageable organ tissue left, or when the situation is life-threatening. 


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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Ishana Gole

Master of Science - MS, Bioscience Entrepreneurship, UCL (University College London)
Ishana is a Biomedical Science student with a keen interest in neuroscience and past experience in online consulting, marketing and advertising.

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