Diabetic neuropathy is a condition that develops in up to 70% of all diabetics. It is a nerve disease that causes a number of symptoms that may not even be felt until later stages. Diabetic neuropathy is indirectly responsible for most cases of wounds and amputations in diabetics. This condition is a form of peripheral neuropathy, which is a disease of nerve tissue and nerve tissue function in the part of the nervous system away from the brain and spinal cord.
The actual cause of diabetic neuropathy is still debated, and in fact, there may be several causes. Some theories add that poor microscopic circulation to the nerve tissue itself found in diabetes causes the disease, and other theories suggest that heightened blood sugar creates chemical changes in the nerve tissue, affecting its function. Regardless of the actual cause, diabetic neuropathy seems to develop in diabetics with poorly controlled blood sugar levels, and in those with good control but are diabetic for many years.
The symptoms of this condition start out as a subtle numbness that may not necessarily be noticed by oneself but can be seen on the exam in a physician’s office. The ability of one to properly feel sharpness, temperature, and even very light touch can be decreased. As the condition evolves, the feeling of numbness can also develop, leading to a feeling that the foot is padded, puffy, or full. Abnormal sensations can also develop, which may include burning pain, tingling, clamping pain or tightness, as well as sharp electrical pains. These symptoms can appear at random, and often at night. In later stages of diabetic neuropathy, the part of the nerves that control muscle function can become affected, leading to cramping and possibly even weakness. Diabetic neuropathy more commonly affects only the feet, but the hands can be involved as well.
The danger of diabetic neuropathy lies in how it changes the ability one has to feel excessive pressure and skin injury in the foot. As the body adjusts to its position on the ground, it changes where pressure is applied to the foot based on feedback from nerve sensors in the skin. When neuropathy is present, this feedback is disrupted and the foot position is not changed. As the pressure increases, the skin becomes damaged. Areas that already receive pressure, such as areas where the skin is callused from normal pressure related to one’s foot structure, develop increased damage. Eventually, the skin underneath can begin to erode and die, resulting in a wound. When this is under a callus, it can be hard to notice and the wound may progress and become infected long before it develops external symptoms. These types of sores are normally very painful, but the lack of sensation due to neuropathy can mask the pain, leading to significant worsening before they are usually noticed and treatment has begun. Even seemingly minimal pressure like the contact of a shoe on the toes can lead to such sores.
Diabetic neuropathy, due to its effect on proper foot sensation, directly places diabetics at increased risk for developing wounds and skin sores. These wounds and sores have a much higher chance of becoming infected due to diabetes' effect on the immune system, and in turn, there is a higher risk for that infection to travel deeper into the foot, leading to gangrene and the potential need for amputation. It is vitally important for all diabetics to protect their feet from harm by assuming one has neuropathy, instead of waiting for later symptoms like numbness and tingling to develop. This protection includes always wearing shoes, even in the home, to protect the foot skin from unfelt puncture wounds, as well as performing a daily visual inspection of one's foot, to look for areas of abnormal pressure and wounds. Once these problem areas are identified, if they can be treated promptly, the more harmful consequences of chronic wounds and foot infections can be prevented.