Persons with diabetes, be it type 1 or 2, are individuals who share a common disease that causes high blood sugars. The effects of the high blood sugars will vary from person to person. Likewise diabetes will affect the feet of each individual person with diabetes in a different manner. Some persons with diabetes have a high risk for foot problems, whereas others are not really at increased risk for foot problems. It is extremely important to screen persons with diabetes to find out who is at increased risk for foot problems. Those who are at increased risk require specialized foot care in order to lower the risk for foot problems. Any person with diabetes should be in the habit of removing his/her shoes and socks upon entering his/her health care providers examining room so that the feet will not be overlooked.

What are the risk factors diabetic related foot problems?

Health care providers examine for four risk factors that can result in foot problems. The factors are prior history of foot diabetes related foot problems, foot deformity, loss of feeling (peripheral neuropathy) and loss of circulation. Peripheral neuropathy or loss of feeling is by far the single greatest risk factor. The greater the number of risk factors the greater the risk for foot troubles.

Risk factors for Diabetes related foot troubles:

Any person with diabetes who has a (1) prior history of diabetes related foot problems is at increased risk for further foot problems.

(2) Deformity of the feet is a risk factor because shoes are not designed to fit deformed feet. A prominent bone could thus rub in shoes and cause a sore or wound. If there is loss of feeling as well as deformity the risk is even greater because the person may not feel the shoe rubbing. Deformity may be as obvious as a prominent bone or a crooked toe; however, it could also be subtle like a thick toenail or a callus. Regardless, if possible deformities should either be addressed with properly fitted shoes or even fixed with an operation.

Loss of circulation or (3) peripheral vascular disease is a risk factor for foot problems. Blood travels to the feet in blood vessels known as arteries. Blood travels away from the feet in blood vessels known as veins. The arteries and veins are like pipes. If the pipes or arteries are blocked then the blood cannot get down to the feet. Blood is very important because it provides fuel and energy to the cells in the feet. Without properly blood supply to the feet, sores can develop and are slow to heal. In more serious cases gangrene can occur. Symptoms of poor blood supply may include: slow healing sores, loss of hair growth on the feet, skin colour change, and cramps or pain in the back of the legs when walking (especially up hill). Pain in the legs when walking is called calf claudication. It occurs because the muscles need fuel and energy when walking. If the muscles are not getting enough fuel and energy because of poor blood supply they start to hurt. After a few minutes of rest the person is able to carry on but only for a short distance before the pain happens again. Cold feet do not necessarily mean poor circulation.

There are treatments available for poor circulation. Sometimes treatment is as simple as diet and exercise. Other times operations are necessary to improve circulation to the feet. Treatment should be discussed with the health care provider. Some cases require referral to a vascular surgeon.

Loss of feeling or (4) peripheral neuropathy is the single greatest risk factor for diabetes related foot problems. High blood sugars caused by diabetes can result in nerve damage. The nerves to the feet are responsible for feeling, movement and sweating. There are thus three different types of neuropathy: sensory, motor and autonomic neuropathies.

Loss of feeling is typically called peripheral neuropathy, but the full term is actually peripheral sensory (feeling) neuropathy. Peripheral sensory neuropathy is the single greatest risk factor for foot problems in persons with diabetes. The nerves to the feet that are responsible for feeling are like burglar alarm sensors. Pain is a form of protection. A good analogy is to think of being on the third floor of a home with a burglar alarm. If someone is breaking into the basement the burglar alarm will send a sound signal upstairs to alert the occupant. If the burglar is quiet and the alarm sensors are broken the intrusion will go unnoticed. The feet in shoes are like the basement of the house. The nerves to the feet are like the burglar alarm sensors. Instead of a sound alarm the nerves send a pain signal. If there is an intrusion into the feet such as a rock in the shoe or rubbing from a seam in the shoe then the nerves should send a pain signal. The individual will thus be forced to stop and check his/her feet. If the alarm is broken, peripheral sensory neuropathy, then the intrusion may go unnoticed until it is too late and damage and/or infection has occurred. Pain is a means of protection for the feet.

Symptoms of peripheral sensory neuropathy include numb feet as well as burning and tingling sensations in the feet. Similar symptoms can also occur in the hands. Peripheral sensory neuropathy usually begins with painful or annoying burning sensations that are typically worse in bed at night. In fact these feelings can be the first signs of diabetes. Eventually the burning progresses to numbness; however, it can take years. There is no way to repair the damaged nerves but medications can be used to treat the initial pain.
Foot deformity can develop from damage to the nerves that cause muscle movement. This is known as motor neuropathy. The nerves are like the electrical supply to the muscles. Without electricity the muscles do not work. The small muscles in the feet are particularly susceptible to nerve damage from diabetes. The small muscles are responsible for stabilizing the toes when walking. If those muscles do not work then the larger muscles in the leg, which also work on the feet, start to over power the unstable toes and deformities such as crooked toes or hammertoes can develop. The damaged nerves and muscles cannot be repaired; however, the foot deformities can sometimes be fixed. If shoe fitting becomes a real problem due to the deformity then surgical repair, if possible, may be a good idea.

The final type of nerve problem is an “autonomic neuropathy.” In this type of neuropathy, the nerves that control sweating are damaged. Dry skin occurs as a result of damage to these nerves. Sweating is important for heat reduction but it is also important for skin moisture balance. Without sweat, the skin dries out and cracks. This can be dangerous because germs can enter through the cracks and cause infection. Dry and cracked skin should be treated with prescription moisturizing creams and regular professional foot care.

In summary persons with diabetes are individuals who share a common disease that causes high blood sugars. The effects of the high blood sugar will vary from individual to individual. The four risk factors for diabetes related foot problems are; prior history, foot deformity, peripheral vascular disease, and peripheral neuropathy. The greater the number of risk factors the greater the risk. Persons with diabetes should try to understand the risk factors and be aware of his/her risk. Those individuals who are high risk need regular professional foot care in order to decrease the risk.

Timothy P. Kalla, BSc, DPM, FACFAS