Neuropathy

Neuropathy is the overall term for all types of nerve damage, and peripheral sensory neuropathy refers specifically to nerve damage affecting the sensory nerves in the body’s peripheral areas – usually the hands and feet but also the arms and legs. Peripheral sensory neuropathy is particularly common in diabetes and is the cause of many foot issues because people can no longer feel their feet and therefore injure them without realising (Diabetes UK 2023a).

In the UK, almost one in ten people aged 55 years or over are affected by peripheral sensory neuropathy (NHS 2022). The main symptoms include (NHS 2022):

An older person with diabetes and peripheral sensory neuropathy is therefore at increased risk of tripping or falling and of injuring their feet without realising.

Ischaemia

Ischaemia occurs when there is a decrease in blood supply to the tissues, leading to a decrease in oxygen and nutrients to the affected area, which may eventually become necrotic. Areas most commonly affected by ischaemia are the heart, brain, intestines and fingers and toes (NHS 2023). This lack of blood supply may occur suddenly because of a blood clot (thrombosis) or embolism (blockage of a vessel frequently caused by a blood clot), or because of a gradual build-up of fatty deposits (atheroma) comprising cholesterol and other waste substances in the walls of the arteries. Atheroma narrows the arteries and restricts blood flow in a process called atherosclerosis. In people with diabetes, ischaemia often affects the feet, where atheroma causes the development of peripheral arterial disease (PAD), which results in a lack of blood supply. Ischaemia is a serious condition and can result in tissue damage and potentially the loss of the affected limb (NHS 2023).

Neuro-ischaemia

The neuro-ischaemic foot is characterised by varying degrees of ischaemia together with neuropathy. This can lead to ulceration, commonly at the margins of the foot or tips of the toes (often at sites of pressure from poorly fitting footwear), or beneath toenails if these have become overly thickened (Edmonds and Foster 2006). Such ulcers are prone to bacterial infection, which along with reduced arterial perfusion in the neuro-ischaemic foot, are important contributing factors in tissue necrosis (Edmonds 2016).

Additionally, individuals with Charcot foot deformity (neuropathy-related disease of the foot’s bones, joints and soft tissue) and ischaemia were noted in studies to be significantly older and have a greater mean duration of diabetes. They presented with more concomitant comorbidities such as ischaemic heart disease and end-stage renal disease compared with patients with neuropathy alone (Meloni et al 2022).

Washing and foot care

The older person and their family and carers should be encouraged to check the older person’s feet every day and immediately report any changes to a healthcare professional. Older people and their family and carers should also be encouraged to (WebMD 2023):

Toenail care

According to Diabetes UK (2023b), the belief that people with diabetes should not cut their own toenails to avoid damaging their feet is misguided. In fact, cutting the toenails safely is crucial to prevent nail and foot issues, aid mobility and reduce the risk of trips and falls (Camden and Islington NHS Foundation Trust 2023). The general advice for older people with diabetes is that their toenails should be trimmed often with a pair of nail clippers and the corners of the nail filed with an emery board (Diabetes UK 2023a).

In terms of toenail care, nurses can advise older people to (WebMD 2023):

Factors such as a loss of sensation due to peripheral sensory neuropathy and suboptimal eyesight, mobility and/or cognition may affect the person’s ability to undertake toenail care – or to undertake it safely – and this needs to be taken into consideration. If it is challenging for the older person to care for their toenails, if their toenails are thickened or painful, or if the person cannot safely see, reach or cut them without assistance, nurses may need to ask the person’s GP for advice and refer them to a foot care practitioner or podiatrist.

Footwear and environment

To reduce the risk of falls and the development of foot ulcers through trauma, it is important to consider the person’s lifestyle, footwear, furniture and home environment (Kalra and Sharma 2018). Feet issues such as untrimmed toenails, bunions, hard skin (callus) or pain can alter the way the person walks, which can in turn affect their balance. Foot pain and/or untrimmed toenails may mean that the person wears ill-fitting shoes or slippers, which further increases the risk of falls. Older people should be encouraged to wear well-fitting shoes or slippers with laces or a Velcro fastening, low heels and non-slip soles (Camden and Islington NHS Foundation Trust 2023).

Annual foot assessment

All people with diabetes aged over 12 years should have an annual foot assessment to check their risk of developing foot complications associated with diabetes (NICE 2019). Before undertaking an annual foot assessment, the competent healthcare professional – often a podiatrist or practice nurse – should first take a comprehensive patient history, including the duration of diabetes, medicines being taken for diabetes and for other health issues, and blood glucose levels. The annual foot assessment should then be undertaken following the procedure detailed in Box 1 (Diabetes UK 2016, 2017).

Foot ulcer risk assessment

Foot ulcers can occur at any time in the life of a person with diabetes, so their annual foot assessment – and any foot examination they undergo – must include a foot ulcer risk assessment. The foot ulcer risk assessment may be undertaken by any competent healthcare professional such as a district nurse or practice nurse (The University of Edinburgh 2021).

If necessary, a care plan will be developed following the assessment. Multidisciplinary working and robust care pathways are crucial to ensure that patients receive appropriate and timely interventions following a risk assessment (Robbie et al 2020, British Geriatrics Society 2021). If a person is deemed to be at high risk of developing a foot ulcer, they must be referred to a specialist foot protection team – either the foot protection service in the community or the multidisciplinary foot team in hospital – in accordance with local guidelines.

Table 1 describes levels of risk of developing a foot ulcer, the corresponding risk factors and the actions to take.

Prevention advice

Diabetes UK (2017) advises that following the annual foot assessment, patients should be informed of their risk level for developing a foot ulcer (Table 1) and given prevention advice. Patients should be advised to (Diabetes UK 2017):

All patients with diabetes should receive verbal and written education about the risk of foot ulcers as well as emergency contact numbers. Beyond providing health education materials, nurses should also be competent in diabetic foot examinations so that they can give appropriate and meaningful foot care advice. If they are in any doubt whether a patient is at risk of developing a foot ulcer, they must immediately refer the patient to a specialist foot care centre (Diabetes UK 2017).

Foot infection

Infection is a common consequence of any wound in a person with diabetes. In people with diabetes and neuropathy, infection often develops following an injury such as cutting the feet on a sharp surface or from a skin condition such as eczema. Foot infection in a person with diabetes is defined as the presence of at least two of the following factors (NICE 2019):

An infected foot ulcer can deteriorate swiftly, as shown by the images in Figure 1 (Edmonds et al 2020a). Recognising foot infection using the factors listed above is therefore essential. If infection is present, urgent referral and management are crucial, the aim being to avoid amputation. People with an active diabetes foot ulcer or spreading infection should be referred to the foot protection service (FPS) (usually in the community) or the multidisciplinary foot team (usually in hospital) within one working day of presentation, as outlined in Table 1 (Diabetes UK 2017, NICE 2019).

Figure 1.

Rapid progression of infection in the neuropathic foot and the ischaemic foot

As with any ulcer, nurses will need to undertake wound care including cleansing and selecting and applying a dressing, but these interventions are outside the remit of this article. More information on the wound care of diabetes foot ulcers can be found, for example, in Chadwick (2021).

Offloading

Offloading, or the relief of the mechanical load from the foot, is recommended as part of the standard treatment of diabetes foot ulcers (NICE 2019, Chadwick et al 2022). While offloading alone does not heal the ulcer, it promotes healing because the foot’s soft tissue is no longer being damaged by pressure from body weight, walking or ill-fitting footwear. Offloading devices include heel casts, inflatable leg troughs and air mattresses. They can be used by community and care services where indicated and according to local guidelines (Munro et al 2021).

Decisions regarding the use of offloading devices and interventions should be made by an appropriately trained healthcare professional such as an advanced clinical practitioner or a GP or following referral to a specialist podiatrist or orthotist. Pressure-relieving mattresses can be requested via the local formulary. Bespoke offloading devices can be made by a podiatrist in primary or secondary care or by a plaster technician in secondary care. Figure 2 shows a selection of bespoke, removable offloading devices.

Figure 2.

Examples of bespoke, removable offloading devices

Foot care at the end of life

It is important to acknowledge that, at the end of life, the goals of diabetes management may change from optimising the patient’s blood glucose levels to managing symptoms and preserving dignity and quality of life (Kalra and Sharma 2018). Because the person will be increasingly prone to injury and pressure damage, it is imperative that nurses implement offloading measures to protect the person’s feet, as described above, to avoid the development of pressure ulcers and diabetes-related ulcers, especially if the person becomes immobile or bedbound.