Diabetes is increasing in prevalence in the UK. According to NICE, it is estimated that more than five million people will have diabetes by 2025. Diabetic neuropathy, and/or peripheral vascular disease in diabetes, increases the risk of developing foot problems such as ulceration.
Developing foot complications associated with diabetes may increase the risk of non-traumatic limb amputation. Patients who have had an amputation due to diabetic foot ulceration have a mortality rate of up to 70% within five years. This mortality rate is likely to reflect the increase in cardiovascular risk associated with diabetes.
There is variation in practice in looking after patients who present with diabetic foot complications. It is important to have a multidisciplinary approach in the management of diabetic foot problems, both in primary and secondary care.
It is important to assess the risk of developing a diabetic foot problem. This may be carried out at opportunistically, at regular diabetes reviews, and when clinically necessary, as well as during hospital admission.
Clinical assessment involves fully examining the feet and removing any dressings that may be present, to assess for neuropathy (using a 10g monofilament), limb ischaemia, ulceration, callus, infection, deformity, gangrene and Charcot arthropathy. It is helpful to obtain an ankle brachial pressure index, whilst noting that patients with diabetes may have a falsely elevated result due to the presence of calcified blood vessels.
Patients with one of the above risk factors are deemed to be at moderate risk of developing a diabetic foot problem or requiring amputation. If there is more than one risk factor present this represents a high risk. Moreover, if there is a history of previous ulceration or amputation or an active diabetic foot problem such as infection, this also represents a high risk.
Management and referral
In patients with a low risk of developing a diabetic foot problem, an annual review is sufficient, with appropriate health education about skin and nail care as well as footwear advice. NICE recommends that patients are advised about foot emergencies and who to contact if necessary.
Those who present with a higher risk should be referred to a foot protection service and assessed within two to four weeks. Patients with diabetes admitted to hospital should be given a pressure redistribution device, and on discharge may be referred to the foot protection service.
Immediate referral may be necessary if there is ulceration with sepsis, gangrene or limb ischaemia. In a patient presenting with a diabetic foot ulcer it is important to assess the size, depth and position of the ulcer. A standardised system such as SINBAD (Site, Ischaemia, Neuropathy, Bacterial Infection, Area and Depth) may be used to assess the severity of the foot ulcer.
Management of diabetic foot ulcers includes: offloading, control of foot infection, control of ischaemia, wound debridement and wound care delivered by appropriately trained individuals, according to NICE.
Case history 1
A 67 year old man with diabetes presents with a chronic foot ulcer. Over the last few days some surrounding erythema has developed. He is afebrile.
If infection is suspected and a wound is present it may be useful to take a wound swab. If the wound has been debrided, a soft tissue or bone sample may be sent for microbiology. It is desirable to send microbiological specimens prior to initiating antibiotic therapy. It is helpful to consider whether there is a possibility of osteomyelitis if there is a deep wound or a chronic clinical picture, therefore an x-ray may be performed. A normal x-ray and the presence of normal inflammatory markers may not exclude the presence of osteomyelitis, therefore if there is a strong clinical suspicion of this a MRI may be indicated.
NICE advises that for mild diabetic foot infections, antibiotics with activity against Gram-positive organisms should be initiated. However in moderate to severe infections coverage for Gram-positive as well as Gram-negative organisms should be initiated. For severe infections intravenous antibiotics are indicated.
Case history 2
A 70 year old woman with type 2 diabetes had an accidental fall which resulted in fracture of the left lateral malleolus. Several months after this she developed significant erythema, swelling and warmth to the left ankle.
If a person with diabetes fractures their foot or ankle, it may progress to Charcot arthropathy. This may be suspected if there is erythema, warmth, swelling or deformity, particularly if there is a background history of neuropathy or renal impairment. Charcot arthropathy may present in the absence of pain or deformity. If this diagnosis is suspected the patient should be referred within one day to a multidisciplinary foot care team and should be advised not to weight-bear. Those patients with Charcot arthropathy are at increased risk of diabetic foot ulceration.
- Dr Kochhar is a GP in Bexhill, East Sussex
|Key learning points|
- National Institute for Health and Care Excellence (NICE) Diabetic foot problems: prevention and management. nice.org.uk/guidance/ng19