Diabetes causes pain in the feet and legs commonly due to a process called neuropathy.
This refers to the damage to nerves caused by the high glucose levels in the body. There are a variety of mechanisms which have been postulated to explain how nerves get affected by diabetes.
In the most common type of pain, the patient experiences burning, tingling or aching in the feet due to the peripheral nerves of the body getting damaged. This process is called distal sensorimotor neuropathy. This may be accompanied by numbness also over the feet.
- In some cases, the pain is disproportionate to the stimulus causing it: for instance, merely touching the skin over the feet or having clothing rub it can cause severe pain.
- A more unusual type of pain is called amyotrophy, where commonly the thigh is affected. The pain is severe, and it is felt deep and may be constant. It is usually on one side.
- Sometimes the nerves supplying the muscles of the lower limbs get affected, causing weakness and an ache in the muscles. This may also lead to imbalances in the feet architecture, which goes on to form calluses and then pain in the affected foot.
- In other cases, the blood supply of the lower limbs gets occluded by the diabetic process leading to severe insufficiency of blood associated with severe pain.
There is also a condition known as Charcot’s foot, which destroys the joints of the foot owing to neural damage. This may result in ulceration over the feet, with subsequent infection and pain.
- Another cause of pain in the lower limbs is the increased risk of infections in people with diabetes.
- This may result in skin and soft tissue infections in the lower limbs, called cellulitis; these result in warmth and redness over the limbs, and are associated with severe pain.
These infections may also extend to involve the bones, causing what is called osteomyelitis (Inflammation of bone).