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Patient Education and Prevention of Diabetic Foot Ulcers
Every podiatrist knows the issues concerning chronically elevated blood sugars that cause peripheral arterial disease (PAD), the resultant development of the comorbidities of diabetes, and the risk factors to their patient’s feet of developing a foot ulcer. However, many patients lack the education to recognize their unique personal risk factors for developing a foot ulcer and subsequently, how to prevent the ulcer. Patients may also not understand how foot ulcers can ultimately result in an amputation. Information on the development of foot ulcers and how to prevent them is a critical component of patient diabetes education and the prevention of foot pathology.
So, the issue to consider is how much do your patients know about their foot health and how does that influence your patients’ behaviors toward prevention? The following article is more geared for patients to read with the hope that, with this information, patients will be better educated on these crucial aspects of their personal risks and care. Alternatively, it can be used as a template for discussions with patients about ulcer prevention and foot health.
An Impactful Story for a Patient Audience
James is a 45-year-old male with type 2 diabetes who came to my office for foot care. He had diabetic sensory neuropathy, which caused him to be unable to sense pain in his feet. He wanted to be sure he was doing everything possible to maintain his foot health and prevent any problems. On his first visit I spent some extra time with him to discuss how diabetes can affect his feet and legs. I gave him a handout focused on the do’s and don’ts of diabetes and his feet. My aim was to educate James on prevention of foot ulcers that can lead to infections. Such infections may require hospitalization and, in a worst-case scenario, amputation. He acknowledged the information I gave him and agreed to read and follow it.
Several months later James called my office reporting a problem with his foot and we saw him that same day. I noted a red, swollen, and warm area on his right foot that had ulcerated. When I asked how it happened, he replied, “A couple of days ago my feet felt cold, and I was uncomfortable. So I placed a heating pad on my feet with the intention to leave it there for just for a short time, just to warm them up. I accidentally fell asleep, and when I awoke about an hour later, my foot was red and swollen. Today my foot looked worse so I thought I should come and see you right away.”
I examined him and found decreased circulation in addition to his previously diagnosed sensory neuropathy. There was an ulcer, 2 cm in diameter, on the bottom of his right foot. Localized redness and swelling tipped me off that he had an infection. I debrided the ulcer and surrounding devitalized tissue and sent a tissue sample for culture and sensitivity. An X-ray of James’s foot showed no evidence of a bone infection, and I ordered the appropriate lab tests. I dressed his wound and placed his foot in a surgical shoe and ordered him a pair of crutches so he could offload the ulcer site. James was placed on an appropriate oral antibiotic along with a local wound care regimen with written home treatment instructions.
I recommended James see a vascular surgeon to have his circulation checked. The results of those exams revealed a mild blockage in one of the main arteries in his right leg, which was surgically corrected. With his circulation restored, I saw James weekly for 8 weeks. He did everything I asked of him for his home care and his ulcer healed uneventfully. He was lucky.
Diabetic Foot Problems by the Numbers
James’s story is not unique. Statistics reveal that worldwide, a diabetic foot ulcer (DFU) happens every 1.2 seconds and a diabetes-related lower extremity amputation happens every 20-30 seconds.1 And worse, 85% of all lower extremity amputations due to diabetes are preceded by a foot ulcer.1 Even worse news is that near 55% of those patients who lose a leg will lose the other leg within 3 years.2 The 5-year mortality rate was very high among patients with any amputation (major and minor combined), ranging from 53% to 100%, and in patients with major amputations, ranging from 52% to 80%.3 So there is a real urgency for patients with diabetes to be educated on the genesis of a foot ulcer and how to protect their feet.
The Role of Underlying Conditions
Contrary to popular thought, diabetic sensory neuropathy and PAD by themselves are not the reasons for the development of diabetic foot ulcers. However, they do represent the underlying conditions that set the stage for the development of diabetic foot ulcers which can lead to infections, hospitalizations, and amputations when combined with a triggering event of foot trauma. There is more to the story that often goes unrecognized.
How Does a Diabetic Foot Ulcer Happen?
Most information on diabetes and foot health describes the conditions that lead to a DFU and amputations to be diabetic sensory neuropathy combined with PAD. This is only partially true as other possible causes of (sensory) neuropathy include a vitamin B deficiency, injury, some drugs, and cancer.4 Other contributing causes of neuropathy include obesity and high triglycerides (a type of blood fat), which may double the risk of neuropathy. Smoking may increase the risk of neuropathy by 42%. High blood pressure has been found to up the likelihood of nerve damage from 11% to 65%. Low levels of “good cholesterol” (high density lipoprotein or HDL) and high readings of “bad cholesterol (low density lipoprotein or LDL) boost risk by up to 67%.5
A Trio of Neuropathies
It’s important for patients to recognize the type(s) of neuropathy that may impact their feet, so they can intervene with appropriate preventive care. Yes, it is true that chronically elevated blood sugars cause circulatory problems that affect the small vessels in the eyes, kidneys, cardiovascular system (brain and heart), and feet. The loss of fresh oxygenated blood and nutrients to the nerves results in a malfunction of the nerves known as neuropathy. It is estimated that around 50% of people with type 2 diabetes and 20% of those with type 1 diabetes will develop diabetic peripheral neuropathy.5
There are 3 types of diabetic neuropathies that are the result of chronically elevated blood sugars. Each type contributes a risk for developing a foot ulcer. Let’s take a quick review of each.
Autonomic neuropathy results from damage to the nerves that control automatic functions of the body. It can affect blood pressure, temperature control, digestion, bladder function, and even sexual function. The nerve damage affects the messages sent between the brain and other organs and areas of the autonomic nervous system. These areas include the heart, blood vessels, and sweat glands.6 In the patient with diabetes, autonomic neuropathy impacting the feet and legs can cause dry skin, cracking, or fissures. These are portals of entry for bacteria that may cause ulcers and infections. Meticulous hygiene and the use of a moisturizing lotion containing urea can help treat the skin dryness in the feet and legs seen in this type of neuropathy.
Motor neuropathy occurs when the motor nerves that control muscle movements become damaged. Motor neuropathy can affect our body’s ability to coordinate movements, particularly walking. It also contributes to a form of foot deformity known as Charcot foot (which causes the foot to swell and become deformed). The symptoms of motor neuropathy may include muscle weakness, loss of control of coordination, muscle twitching, and muscle paralysis.7
Motor neuropathy is responsible for decrease in muscle mass in the 13 small muscles in the forefoot that control the fine movement of the toes (the lumbricales and interossei muscles) resulting in toe contractures and the deformity known as hammertoe. Hammertoes can rub against the shoe and cause corns that can be the trigger for developing an ulcer. A conservative approach to these problems involves changing to shoes with a deeper and wider toe box that will allow appropriate room and prevent rubbing against the shoe. Surgical correction is another solution.
Sensory neuropathy affects the nerves responsible for sensation throughout the body. It most commonly affects the feet, legs, hands, and arms. The symptoms may include numbness, or a loss of sensation, coldness, tingling, burning, and extreme sensitivity to touch. Sensory neuropathy, especially in the feet, can cause people to be unaware of an injury, which, in conjunction with poor wound healing, can set the stage for a foot ulcer.4 It is vital to inspect the feet daily for any break in the skin that could lead to an ulcer and to practice preventive foot health behaviors.
A Trio of Traumas
A thermal injury was the triggering event that led to James’s ulcer, although not all foot ulcers are the result of this specific type of injury. Trauma is an injury (such as a wound) to living tissue caused by an extrinsic agent. Sensory neuropathy leaves the foot vulnerable to three types of traumas, discussed below, which can trigger diabetic foot ulcers.
Mechanical trauma is by far the most common in the “at-risk” diabetic foot, and manifests in many different ways. Something that would seem innocuous, like an improperly placed sock that folds over on itself, can result in abnormal pressure against the foot in the shoe, causing an ulcer. Other examples of mechanical trauma include walking barefooted and stepping on a foreign body like an insulin needle or piece of glass or walking to the bathroom in the dark and stubbing a toe on the door frame. Other causes of mechanical trauma include dropping an object on an unprotected foot and improperly fitted foot gear. Bathroom “surgery” is another common form of trauma when patients with diabetes and poor eye motor coordination in the presence of poor lighting use unsterile or improper instruments (scissors, razor blades, clippers) to trim their nails, corns or calluses on their feet at home. I have treated patients who cut the end of their toe off doing this and never felt it.
Chemical trauma can also be a trigger to developing a diabetic foot ulcer. The most common form of chemical trauma is from over-the-counter medications used for warts, ingrown toenails, corns, and calluses. All of these medications share one common ingredient, salicylic acid, as this chemical has the capacity to painlessly destroy human tissue. Use of these medications on the at-risk, insensate foot with vascular compromise usually results in a whitish chemical burn that can trigger an ulcer. Do not use any product that contains salicylic acid on the feet unless specifically directed by your doctor. Instead of self-treatment, seek professional foot care.
Thermal trauma is the third member of this devastating triad. Thermal trauma can be the result of exposure of the at-risk foot to either heat or cold. Many people with diabetes report that, either objectively or subjectively, they feel their feet are cold. All too often because the patient’s feet are numb, patients do not feel external heat sources and expose their foot for extended periods of time to things like heating pads, hot water bottles, fireplaces, or radiators. The result of this is a thermal burn, which results in an ulcer. Thermal trauma can also occur from walking barefoot on hot surfaces like concrete or asphalt.
Conversely, exposure to cold thermal injury can also result in an ulcer; however, injury from exposure to heat is much more common. A good strategy to protect feet from cold is to wear two pairs of socks. Patients should be aware of their environmental surroundings, refrain from exposing their feet to artificial heat sources, and avoid exposing their feet to temperature extremes.
Understanding the Risks and Traumas
Patients with diabetes have unusual risk factors for the development of foot ulcers due to the underlying conditions of neuropathy and PAD combined with potential triggering traumas to their feet. The key to preventing foot ulcers is understanding the 3 types of neuropathies and the 3 types of triggering traumas that can cause a foot ulcer. Patients need to know that the benefit of being vigilant about their foot health can prevent foot ulcers, infection, hospitalization, and the likelihood of an amputation.
Dr. Hinkes is President and Chief Medical Officer of ePrevenir, Inc. He is board certified by the American Board of Foot and Ankle Surgery and is a Fellow of the American College of Foot and Ankle Surgeons and the American Professional Wound Care Association. He is the author of “Healthy Feet for People With Diabetes” and “Keep the Legs You Stand On,” available at www.amazon.com.
References
1. D-Foot International. Diabetic foot facts.
2. Access Prosthetics. 15 limb loss statistics that may surprise you.
3. Thorud JC, Plemmons B, Buckley CJ, Shibuya N, Jupiter DC. Mortality after major nontraumatic amputation among patients with diabetes and peripheral vascular disease: a systematic review. J Foot Ankle Surg. 2016; 55(3):591–9.
4. Diabetes Talk. Diabetic sensory neuropathy. Published April 10, 2018.
5. Ullman K. Tips for healthy feet with diabetes. Diabetes Self-Management. Published Nov. 30, 2021.
6. Mayo Clinic. Autonomic neuropathy.
7. Diabetes.co.uk. Motor neuropathy. Published June 10, 2022.
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