Diabetes is an increasingly common disease in the United States and around the world. The high blood sugar (glucose) that is characteristic of diabetes wreaks havoc on many different areas of the body, and it can have life- and limb-threatening complications if left untreated.
Feet are very sensitive to the effects of diabetes. Potential problems include loss of feeling, diminished blood supply, and severe infection that requires amputation. According to the 2011 National Diabetes Fact Sheet, more than 60% of non-traumatic lower-limb amputations occur in people who have diabetes.
The good news is that blood sugar control and regular preventative care can significantly reduce the chances of diabetic complications. In fact, it is estimated that preventative foot care and patient education can reduce a person's chance of diabetic limb amputation by up to 85%.
Possible Effects of Diabetes on the Feet
According to the American Diabetes Association, approximately 60% to 70% of diabetics have some form of neuropathy or damage to nerves. Long-term high levels of blood glucose result in progressive damage to nerves that often manifests as sensory or motor neuropathy.
Sensory neuropathy results in decreased or impaired feeling in the feet. This means a diabetic may have a foot injury -- such as a wound from stepping on a sharp object -- and not be able to feel it. Sensory neuropathy increases the risk of a diabetic foot ulcer, which is a wound that is slow-healing, or even non-healing, and is susceptible to infection. If untreated, a diabetic ulcer can extend through the skin and soft tissue to underlying bone. Other signs of sensory neuropathy include shooting pain and burning or tingling sensations in the limbs, often at night.
Some diabetics develop motor neuropathy, which appears as leg and foot muscle weakness and decreased muscle mass. Motor neuropathy occurs when nerves that control muscles are damaged. This can cause difficulty walking and lead to changes in foot shape, all of which expose areas of the feet to increased friction and pressure. Contracture of the toes, an example of foot-shape change, creates excess pressure under the ball of the foot and increases the risk of ulcers.
Long-term high blood glucose also has adverse effects on blood vessels. This can result in peripheral arterial disease or PAD. When the linings of the arteries carrying blood to the legs become damaged, atherosclerosis occurs. Atherosclerosis is a plaque that deposits in the artery, causing a narrowing that will decrease blood flow to the feet. This diminished blood flow can cause delayed wound healing, pain (especially in the toes) and an increased risk of tissue death or gangrene. Symptoms of PAD include skin that is cool to the touch and pale in color, and leg pain while walking.
The skin is affected by high blood sugar in a number of ways. Some skin problems, such as ulcers and delayed healing, are due to vascular and neurological changes that can occur with diabetes. Another form of neuropathy that can sometimes strike diabetics is autonomic neuropathy, and is associated with the following skin changes:
Swelling of the feet and ankles
Skin that feels very warm to the touch
By far the most common and potentially problematic skin change that affects diabetics is a corn or callous. If a diabetic has decreased the perception of pain because of neuropathy, then certain areas of the feet will experience increased pressure. These areas, often the toes or soles, frequently develop corns and calluses that can easily become ulcers in a diabetic foot.
Diabetic feet and ankles can develop blisters or rashes that cause discoloration. Sometimes skin and toenails become thickened and take on a yellow discoloration. Diabetics are also more prone to toenail fungus, another cause of toenail thickening.
Knowing the potential complications of diabetes can be frightening, but the best way to protect yourself is through prevention. When it comes to protecting your feet, be sure to include regular visits to your doctor and podiatrist if you suffer from diabetes.