Before any treatment is instigated, exclusion of non-diabetic causes of neuropathy is suggested. This includes assessment for vitamin B12 deficiency, hypothyroidism and renal disease, and a review of neurotoxic drugs, including excessive alcohol consumption. Neuropathy may be seen with other foot conditions, such as deformity and peripheral arterial disease, so a comprehensive clinical assessment other than for neuropathy is appropriate.
The clinical focus is on prevention by optimising glycaemic management and early recognition, facilitated by good history and routine sensory testing.
Assessment
People with type 2 diabetes should be checked for diabetic peripheral neuropathy at diagnosis, and at least annually thereafter, but more frequently (ie 3–6 monthly) should abnormal clinical findings be present such as peripheral arterial disease and/or foot deformity.3,4
Tests to assess for diabetic peripheral neuropathy are shown in Box 1. Combinations of more than one test have >87% sensitivity in detecting diabetic peripheral neuropathy. Loss of 10-g monofilament perception and reduced vibration perception predict heightened risk for foot ulcers.5
There are several neuropathy scoring systems (Diabetic Neuropathy Symptom Score, Neuropathy Impairment Score and Michigan Neuropathy Screening Instrument) that may be used with examination to confirm diagnosis and assess severity.6–8
Motor neuropathy sometimes occurs, with muscle wasting, weakness and abnormalities of gait. This can contribute to foot problems by altering the biomechanics of the ankle and foot.
Cardiovascular autonomic neuropathy should be suspected with resting tachycardia (>100 bpm) or orthostatic reduction in blood pressure (a fall in systolic blood pressure >20 mmHg on standing without an appropriate heart rate response). This applies to people not currently on antihypertensive agents such as beta-blockers. It is associated with increased cardiac event rates.
Box 1. Assessments for peripheral neuropathy5
- Small fibre:
- Large fibre:
- vibration perception (using a 128-Hz tuning fork)
- 10-g monofilament pressure sensation at the distal plantar aspect of both great toes and metatarsal joints
- assessment of ankle reflexes
- loss of protective sensation (10-g monofilament)
Management
Management mainly involves professional assessment and foot care to prevent diabetes-associated foot disease. The appearance of peripheral neuropathy should prompt a review of glycaemic management and consideration of intensified management to prevent progression.2 See the Table of recommendations for pharmacotherapy management. Consider topical capsaicin topically when oral pharmacotherapy is not tolerated or contraindicated.
The pain of peripheral neuropathy can be assessed using the DN4 neuropathy score and can be difficult to manage, although there is evidence that several agents can improve symptom control and quality of life.2 Options for pain management therapy are in the Table of recommendations.
Autonomic neuropathy may require involvement of a specialist multidisciplinary team approach to address each individual’s presentation (eg gastroenterology with gastroparesis).
For information about the Foot Forward program to prevent amputation, contact Diabetes Australia.