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. The resulting bone deformity is known as Charcot foot.

Due to advanced peripheral nerve dysfunction associated with diabetes (diabetic neuropathy), patients’ feet have a dryness ofthe skin and a reduced ability to feel pain (nociception).
Hence, minor injuries may remain undiscovered and subsequently progress to a full-thickness diabetic foot ulcer. Moreover, foot surgery is well tolerated without anaesthesia. The feet’s insensivity to pain can easily be established by 512 mN quantitative pinprick stimulation.

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 the 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. Research estimates that the lifetime incidence of foot ulcers within the diabetic community is around 15% and may become as high as 25%.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.