Several factors predispose to the development of diabetic foot problems:
- microangiopathy - this is responsible for the peripheral neuropathy that affects sensory, motor and autonomic nerves. The sensory neuropathy leads to decreased awareness of injury from foreign bodies and footwear. The motor neuropathy causes distortion of the weight bearing characteristics of the foot. Loss of reflexes and deformities frequently accompany muscular involvement. The feet may be splayed - neuropathic joints. The autonomic neuropathy causes disruption of control of sweating and vascular supply.
- restricted capillary perfusion; narrowing of arterioles
- AV communications form beneath the skin. These divert nutrition away from the skin, and contribute to poor healing.
- bacterial growth is favoured by impaired tissue energy metabolism and the glucose-rich tissue environment.
The patients most at risk of development of diabetic foot complications are:
- the older, poorly controlled, type 2 diabetics
- patients with long standing type 1 diabetes
If a diabetic has other microangiopathic complications e.g. retinal, then they a have a greater chance of developing foot problems.
The foot problems are usually either of a primarily neuropathic or a primarily atherosclerotic origin - diabetic patients tend to develop atherosclerosis at an earlier age than non-diabetics.