Complications of diabetesThe diabetic foot
Section snippets
Definitions and epidemiology
In this contribution, the term ‘diabetic foot’ includes any pathology that results directly from diabetes mellitus or its long-term complications.
Foot problems account for more hospital admissions than any other long-term complications seen in patients with diabetes mellitus. Understanding the causes of these problems enables early recognition of patients at high risk. It has been shown that up to 50% of amputations and foot ulcers in diabetes can be prevented by effective identification and
Pathogenesis of foot ulceration
Foot ulceration occurs as a result of trauma (often unperceived) in the presence of neuropathy and/or peripheral arterial disease (PAD) (Figure 1). Contrary to popular belief, infection is not a primary cause of foot ulcers, but is a secondary phenomenon after ulceration of the protective epidermis.
Advanced somatic neuropathy results in insensitivity, facilitating trauma and altered proprioception and small-muscle wasting. This, in the presence of limited mobility in the subtalar and mid-foot
Identification of the at-risk foot
Careful inspection and examination of the foot is an integral part of the annual medical review that all patients with diabetes should expect. The clinician should never rely on symptoms alone to identify high-risk patients: 50% of patients with insensitive feet have no previous history of neuropathic symptoms, and claudication may not be prominent in those with ischaemic feet. Patients at greatest risk of ulceration are those with:
- •
evidence of neuropathy
- •
evidence of ischaemia
- •
foot deformity (e.g.
Prevention of foot problems
Patients without risk factors who have healthy feet should be given general advice on foot hygiene, nail care and the purchase of footwear. Their risk status should be reviewed annually.
Patients with any risk factor should be reviewed more frequently and educated about preventive foot care. High-risk patients should be advised to:
- •
wash and inspect their feet daily
- •
use creams or lotions to prevent dry skin and formation of callus
- •
always have their feet measured when purchasing shoes
- •
avoid walking
Diabetic foot ulceration
Despite preventive measures, patients can still develop ulcers, so a system of classification is important. In recent years, many new ulcer classification systems have been proposed; one of the most commonly used was devised at the University of Texas (UT) (Table 1). In this system, grades refer to the depth of the wound, and each grade has four stages, depending on the presence or absence of infection and/or ischaemia.1, 2, 3
Peripheral arterial disease and gangrene
Whereas there is no doubt that PAD is more common in patients with diabetes, screening methods effective in non-diabetic patients are less reliable in diabetes, particularly in the presence of neuropathy. Qualitative Doppler waveform analysis and toe-pressure measurement have been shown to be the best measures.
PAD in diabetes is more severe, is more likely to affect distal vessels and is associated with a poorer outcome than in non-diabetic patients. However, any patient with PAD associated
Aftercare
It is essential to remember that hospitalized patients with diabetes are at potential risk of further insensitive ulceration, particularly if bed rest is prolonged. Protection of the heels and other pressure points is of paramount importance, and devices such as leg troughs are invaluable.
After discharge, all patients require education about foot care and careful follow-up, preferably by the foot-care team, to prevent recurrent ulceration. Special footwear (e.g. extra-depth shoes with
Charcot neuro-arthropathy (CN)
CN is non-infective arthropathy in a well-perfused, insensitive foot. It is a progressive condition characterized by joint dislocations, pathological fractures and debilitating deformities. It results in progressive destruction of bone and soft tissues and, in its most severe form, can cause significant disruption of the bony architecture and result in amputation.
Recent advances have increased understanding of the mechanisms involved in the pathogenesis of osteopenia and osteoporosis, and the
The foot in remission
Unfortunately, recurrence is common even after resolution of a foot ulcer or acute CN.1 Recurrence rates after ulcer healing can be as high as 40% after 1 year and 65% after 5 years. Individuals with CN have up to a 50% chance of developing the same problem in the contralateral foot, and are also at very high risk of ulceration in either foot. Thus, the concept of ‘remission’ may be preferable to ‘healing’.1 Analogous with cancer, remission alerts the patient to the possibility or even
The future
Extensions of 21st-century technology may help in the prevention of ulcers, especially recurrent ones. It is well known that a pre-ulcerative neuropathic foot heats before it ulcerates, as a consequence of inflammation.1, 5 Thus, a novel remote foot-temperature monitoring system (in the form of a wireless daily-use thermometric foot mat) has been shown to predict impending foot ulcers. Using an asymmetry of 2.2°C, the system correctly identified 97% of observed ulcers.5 In-shoe pressure and/or
Key References (5)
- et al.
Diabetic foot ulcers and their recurrence
N Engl J Med
(2017) - et al.
Current challenges and opportunities in the prevention and management of diabetic foot ulcers
Diabetes Care
(2018)