LIVING WITH DIABETES and managing the disease is a challenge for everyone involved. Preventing and managing complications of diabetes and preventing them from worsening are particularly challenging. These include small blood vessel damage (microvascular disease), which includes retinopathy, nephropathy, and neuropathy.
Although it's not immediately life threatening and doesn't result in readily apparent disorders such as visual impairment and chronic kidney disease, diabetic peripheral neuropathy (DPN) significantly affects quality of life due to distal sensory loss and pain as well as other signs and symptoms, morbidity, and costs to both the patient and the healthcare system. Importantly, it's also a major cause of preventable lower extremity amputations. This article details how to assess patients for DPN and how this common complication of diabetes can be managed.
Several syndromes that are distinguished by the affected nerves and resulting signs and symptoms are included in the term diabetic neuropathy.1 DPN is also commonly referred to as chronic sensorimotor neuropathy, diabetic symmetric polyneuropathy, and more commonly, painful diabetic neuropathy.
Although DPN prevalence estimates range from 10% to 90% of those with diabetes, most experts agree that about 25% to 50% of people with type 1 and type 2 diabetes are affected.1 The number of patients with DPN has increased in recent years while the numbers of patients with ulcers, peripheral arterial disease, and lower extremity amputation have decreased.2,3 Although the reason for improvements isn't known, it's likely to be a combination of better preventive foot care, intensive blood glucose management, and improved therapies for foot ulcers.
The exact cause of DPN isn't known, but nerve damage is linked to both the duration of diabetes and chronically elevated blood glucose levels.1,4 Nerve fibers of any size can be damaged.1 Over time, the peripheral sensory nerves are damaged in a symmetrical stocking-glove pattern, starting with the longest nerves. Nerves in the feet and legs are affected more often than those in the hands and arms. Although loss of sensation increases the risk for amputations, DPN is more often associated with pain, significantly impacting quality of life.
Often severe and debilitating, DPN may be described as burning, painful tingling, “pins and needles,” or similar to electric shocks, deep, stabbing, and aching. Many patients experience all stimuli as painful (allodynia): the sensation of anything touching the affected area, such as bedclothes or clothing, is extremely painful. Other patients experience sensory loss. The pain will eventually fade, generally due to the death of the nerve rather than an improvement in DPN.1
Guidelines from the American Diabetes Association recommend screening all patients with diabetes for DPN: those with type 2 diabetes beginning with diagnosis and those with type 1 diabetes starting 5 years after diagnosis. Patients with either type of diabetes should be screened at least annually thereafter.5 Screening includes evaluation of vibration sense (using a 128-Hz tuning fork), pinprick sensation, light touch sensation (using the 10-gram monofilament), and Achilles tendon reflex.5
Besides assessing pain intensity on a scale of 0 to 10, asking patients to describe their peripheral sensations can help to establish the diagnosis. Are sensations described as sharp pain, dull pain, coldness, sensitivity, or itchiness?1,6 Because many patients say symptoms are worse at night, also assess the patient's sleep patterns.6 It's also helpful to determine if patients can link their symptoms to specific situations (such as hyperglycemia) or if they've found strategies to ease the pain (for instance, standing on a cold tile floor or using over-the-counter or “natural” products).
Equally important is assessing whether DPN interferes with patients' ability to manage their diabetes. Has it affected their quality of life or that of their family members, the ability to do their job, and relationships with others? Because depression is about twice as likely to occur among people with diabetes than people without,7 particularly those experiencing complications of diabetes, assessing the impact of the DPN on the patient's life is just as important as understanding the physical aspects of the pain.8
Despite the fact that DPN is extremely common, it's often unrecognized and untreated. The diagnosis is confirmed largely by signs and symptoms, sensory testing, and nerve conduction studies.5,9,10
In the past, many people with DPN were told that they'd just have to learn to live with the pain. Due to a great deal of research, medications and other therapies can now be offered to affected patients.
Hyperglycemia can increase sensitivity to all types of pain.1 For this reason, improving glycemic control with intensified therapy is the first step to managing DPN, particularly when patients report that the pain occurs primarily with episodes of hyperglycemia. Improving blood glucose levels also modestly decreases further nerve damage.5 Because of the effects of smoking on DPN and other complications of diabetes, smoking cessation strategies and programs should also be offered to all patients with diabetes who smoke.
Although available medications aren't effective for all patients, they offer symptom relief for many. Teach patients that they'll need to take some medications for several weeks before they'll sense any improvement so they should continue taking their medication as prescribed. Also teach them that if one medication doesn't work, others will be tried. Tell them to contact their healthcare provider if the medication isn't effective.
A recent evidence-based guideline for the treatment of DPN noted that antiepileptic drugs, certain antidepressants, and opiates may be effective for treating neuropathic pain in patients with diabetes.11 Pregabalin (an antiepileptic drug) and duloxetine (a serotonin and norepinephrine reuptake inhibitor antidepressant) are currently the only two medications with an FDA-approved indication for treating the pain of DPN. Other medications with evidence of efficacy include venlafaxine, amitriptyline, gabapentin, valproate, and opioids such as morphine, tramadol, and extended-release oxycodone; however, these aren't FDA-approved for painful neuropathy.11 Capsaicin extended-release cream and lidocaine 5% patches have also been effective for some patients.11
Patients can realistically expect about a 30% to 50% reduction in symptoms.12 Trying different medications and intensified diabetes management for improved blood glucose control may improve these results.1
Some nonpharmacologic therapies have been studied to determine treatment efficacy. Using the same evaluation criteria that were used in the medication studies, DPN guidelines indicate that some evidence shows percutaneous electrical nerve stimulation may decrease pain and improve quality of life.11 The evidence isn't sufficient to support recommendations for low-intensity laser treatment, electromagnetic field treatment, Reiki therapy, exercise, or acupuncture.5
Encourage patients to explore other strategies to manage their symptoms. For example, using elastic body stockings (available at dance or exercise stores), pantyhose, or foot cradles can help keep clothes and bedcovers away from sensitive skin and may relieve pain for some patients. Also teach patients with DPN appropriate foot care strategies.13
DPN is an extremely common and debilitating complication of diabetes with potentially severe physical and emotional consequences. Nurses have an important role to play by assessing signs and symptoms and their impact, helping patients understand their treatment options, and supporting their efforts.
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