Chapter 31: Neuropathy
Canadian Diabetes Association 2013 Clinical Practice Guidelines for the Prevention and Management of Diabetes in Canada
- Detectable sensorimotor polyneuropathy will develop within 10 years of the onset of diabetes in 40% to 50% of people with type 1 or 2 diabetes.
- Up to 50% of children with type 1 diabetes will have subclinical polyneuropathy.
- While clinical neuropathy is uncommon in people with type 1 diabetes within the first 5 years after the onset of diabetes, people with type 2 diabetes may have neuropathy at the time of diagnosis.
- Risk factors for neuropathy include elevated blood glucose levels, elevated triglycerides, high body mass index, smoking and hypertension.
- Foot ulceration, which depends on the degree of foot insensitivity, and amputation are important and costly sequelae of diabetic neuropathy.
- Although not all patients with neuropathy have motor or sensory symptoms, the neuropathic pain associated with symptomatic disease is frequently bothersome and often limits physical activity, quality of life and work productivity.
- Patients with neuropathy utilize more health resources than those without this complication.
- Mononeuropathy, particularly carpal tunnel syndrome, is common in people with diabetes and can be difficult to diagnose. The underdiagnosis of neuropathy is a fundamental problem in the primary care of people with diabetes and impedes the benefits of early identification, the management necessary to achieve improved glycemic control and the prevention of neuropathy-related sequelae.
Screening for Peripheral Neuropathy
- In people with type 2 diabetes, screening for peripheral neuropathy should begin at diagnosis of diabetes and occur annually thereafter. In people with type 1 diabetes, annual screening should commence after 5 years' postpubertal duration of diabetes [Grade D, Consensus].
- Screening for peripheral neuropathy should be conducted by assessing loss of sensitivity to the 10-g monofilament or loss of sensitivity to vibration at the dorsum of the great toe [Grade A, Level 1].
- In individuals with significant early progressive symptoms of neuropathy or in whom a clinical suspicion of nondiabetic neuropathy exists, referral for additional neurological evaluation is indicated.
Management of Neuropathy
- People with diabetes should be treated with intensified glycemic control to prevent the onset and progression of neuropathy [Grade A, Level 1A, for type 1 diabetes; Grade B, Level 2,] for type 2 diabetes].
- The benefits of intensive insulin treatment persist for over a decade for the primary prevention of neuropathy.
- Other than good glycemic control, no other disease-modifying treatments are currently available.
- Few patients have complete relief of painful symptoms with any treatment, and a 30% to 50% reduction in baseline pain is considered to be a clinically meaningful response.
- The following agents may be used alone or in combination for relief of painful peripheral neuropathy (PDN):
- Anticonvulsants (pregabalin [Grade A, Level 1], gabapentin,* valproate* [Grade B, Level 2])
- Antidepressants (amitriptyline,* duloxetine, venlafaxine*) [Grade B, Level 2]
- Anticonvulsants and antidepressants are most often used as first-line therapy
- Opioid analgesics (tapentadol ER, oxycodone ER, tramadol) [Grade B, Level 2]
- Opioids are effective for PDN and are used mostly when other treatments fail.
- Most practitioners advise against the use of opioids for PDN due to the potential for dependency, tolerance, dose escalation and diversion.
- Topical nitrate spray [Grade B, Level 2]
- Other effective therapeutic options include topical capsaicin and transcutaneous electrical nerve stimulation.
- Effective treatment with capsaicin involves short-term pain that limits its acceptability and generalisability in clinical practice.
- The surgical release of distal lower limb nerves is not recommended due to lack of evidence supporting efficacy and the possible complications of foot and ankle surgery in patients with diabetes.
- Symptomatic autonomic neuropathy is infrequent. The diagnosis of symptomatic autonomic neuropathy is based on the exclusion of specific cardiovascular, gastrointestinal or genitourinary manifestations through assessment by a specialist in the affected system and is currently treated based on expert opinion.
*Denotes that this drug is not currently approved by Health Canada for the management of neuropathic pain associated with diabetic peripheral neuropathy.
For definitions of the levels of evidence cited in this chapter, please refer to the Guideline Recommendations: Levels of Evidence.
If you would like more details on this topic, please visit the Canadian Diabetes Association Clinical Practice Guidelines: Chapter 31. For information regarding rapid screening for diabetic neuropathy, please see Appendix 8.