Diabetic Foot
A diabetic foot is any pathology that results directly from peripheral arterial disease (PAD) and/or sensory neuropathy affecting the feet in diabetes mellitus; it is a long-term (or "chronic") complication of diabetes mellitus. Presence of several characteristic diabetic foot pathologies such as infection, diabetic foot ulcer and neuropathic osteoarthropathy is called diabetic foot syndrome.
Due to advanced peripheral nerve dysfunction associated with diabetes (diabetic neuropathy), patients' feet have a reduced ability to feel pain. This means that minor injuries may remain undiscovered for a long while, and hence may progress to a full-thickness diabetic foot ulcer. The feet's insensivity to pain can easily be established by 512 mN quantitative pinprick stimulation. Research estimates that the lifetime incidence of foot ulcers within the diabetic community is around 15% and may become as high as 25%.
In diabetes, peripheral nerve dysfunction can be combined with peripheral artery disease (PAD) causing poor blood circulation to the extremities (diabetic angiopathy). Around half of patients with a diabetic foot ulcer have co-existing PAD. Vitamin D deficiency has been recently found to be associated with diabetic foot infections and increased risk of amputations and deaths.
Where wounds take a long time to heal, infection may set in, spreading to bones and joints, and lower limb amputation may be necessary. Foot infection is the most common cause of non-traumatic amputation in people with diabetes.
Prevention
Prevention of diabetic foot may include optimising metabolic control via the regulation of blood glucose levels; identification and screening of people at high risk for diabetic foot ulceration, especially those with advanced painless neuropathy; and patient education in order to promote foot self-examination and foot care knowledge. Patients would be taught routinely to inspect their feet for hyperkeratosis, fungal infection, skin lesions and foot deformities. Control of footwear is also important as repeated trauma from tight shoes can be a triggering factor, especially where peripheral neuropathy is present. Evidence is limited that low-quality patient education courses have a long-term preventative impact.
"Of all methods proposed to prevent diabetic foot ulcers, only foot temperature-guided avoidance therapy was found beneficial in RCTs" according to a meta-analysis.
Treatment
Treatment of diabetic foot ulceration can be challenging and prolonged; it may include orthopaedic appliances, surgery and antimicrobial drugs and topical dressings.
Most diabetic foot infections (DFIs) require treatment with systemic antibiotics. The choice of the initial antibiotic treatment depends on several factors such as the severity of the infection, whether the patient has received another antibiotic treatment for it, and whether the infection has been caused by a micro-organism that is known to be resistant to usual antibiotics (e.g. MRSA). The objective of antibiotic therapy is to stop the infection and ensure it does not spread.
It is unclear whether any particular antibiotic is better than any other for curing infection or avoiding amputation. One trial suggested that ertapenem with or without vancomycin is more effective than tigecycline for resolving DFIs. It is also generally unclear whether different antibiotics are associated with more or fewer adverse effects.
It is recommended however that the antibiotics used for treatment of diabetic foot ulcers should be used after deep tissue culture of the wound. Tissue culture and not pus swab culture should be done. Antibiotics should be used at correct doses in order to prevent the emergence of drug resistance. It is unclear if local antibiotics improve outcomes after surgery.