- Foot problems are common in type-1 and type-2 diabetics
- 20-40% of diabetics have peripheral neuropathy
- Many also have features of peripheral vascular disease
- 15% of diabetics develop foot ulceration
- Diabetes is the leading cause of non-traumatic lower limb amputation
Pathophysiology
- The diabetic foot results from a combination of neuropathy and
ischaemia
- Neuropathy has sensory, motor and autonomic components
- Sensory loss results in loss of protective sensation and unnoticed
foot injuries
- Loss of motor control to the small muscles of the feet results in a
claw foot deformity
- Autonomic neuropathy leads to vasomotor denervation and
arteriovenous shunting
- This compromises the ability to direct blood flow to the capillary
beds
- Ischaemia can affect both the large and small vessels
- Large vessels disease results in atheroma of the femoral, popliteal
and tibial vessels
- Small vessel disease affects the microcirculation
- Other contributing factors include:
- Poor vision
- Limited joint mobility
- Cerebrovascular disease
- Peripheral oedema
- In patients with foot ulceration healing is impaired
- This results from:
- Impaired fibroblast function
- Deficiency in growth factors
- Abnormalities of the extracellular matrix
Management
- Prevention of complications is preferable to the need for active
management
- Patients should be monitored and self-care encouraged
- They should be educated about
- Washing
- Care of cores and calluses
- Toenail cutting
- Suitable footwear
- In those with ulceration assessment should be made of:
- Infection
- Vascular insufficiency
Picture provided by Kevin Varty, Addenbrookes's
Hospital, Cambridge
Management of infection
- Wound swabs often show both gram-negative, gram-positive and
anaerobic bacteria
- Osteomyelitis if usually due to Staph. aureus
- Plain radiography or MRI may demonstrate the extent of the infection
- The threshold for antibiotic use should be low
- The antibiotics used should be based on culture sensitivities
- Surgery may be required if progression despite antibiotic treatment
Management of vascular insufficiency
- All patients with diabetic ulceration should undergo non-invasive
vascular assessment
- The ABPI should be calculated
- This may be falsely elevated due to arterial calcification
- Normal values may still be recorded in diabetics with significant
major vascular disease
- Revascularisation should be considered if arterial insufficiency is
present
- Diabetics have a predisposition for disease in medium-sized vessels
especially at the popliteal trifurcation
- The distal pedal vessels are often spared
- Femoro-distal bypass grafting may be required
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