Diabetic Neuropathy

Original Editor - Wendy Walker

Lead Editors  

Introduction

Diabetic neuropathy is the most common complication of Diabetes Mellitus (DM), affecting as many as 50% of patients with type 1 and type 2 DM. A large American study estimated that 47% of patients with diabetes have some peripheral neuropathy.

Neuropathies are characterized by a progressive loss of nerve fibre function.

Clinically Relevant Anatomy

add text here relating to clinically relevant anatomy of the condition

Mechanism of Injury / Pathological Process

Causes

Current thinking on the causes of diabetic neuropathy is that it is likely to be multifactorial

Contributary factors:

• Hyperglycaemic exposure - causing increased levels of intracellular glucose in nerves, leading to saturation of the normal glycolytic pathway
• Elevated lipids
• Hypertension
  
• Increased production of free radicals in diabetes - this may be detrimental via several mechanisms that are not fully understood
  

Development of symptoms depends on many factors, such as total hyperglycemic exposure and other risk factors such as elevated lipids, blood pressure, smoking, increased height, and high exposure to other potentially neurotoxic agents such as ethanol. Genetic factors may also play a role. Important contributing biochemical mechanisms in the development of the more common symmetrical forms of diabetic polyneuropathy likely include the polyol pathway, advanced glycation end products, and oxidative stress.

Risk Factors

Risk factors associated with more severe symptoms:

• smoking
• poor glycaemic control
• advanced age
• long duration of Diabetes disease
• heavy alcohol intake
• tall stature! It is thought that this may be because longer nerve fibres are more susceptible to injury.
  

Clinical Presentation

More than half of cases are distal symmetric polyneuropathy. Focal syndromes such as carpal tunnel syndrome (14-30%), radiculopathies/plexopathies, and cranial neuropathies account for the rest.

Motor Symptoms

Motor problems may include distal, proximal, or more focal weakness. In the upper limbs, distal motor symptoms often include impaired fine hand coordination.

Mild drop foot or frequent tripping may be early symptoms of lower limb weakness. Symptoms of proximal limb weakness include difficulty climbing up and down stairs, difficulty getting up from a seated or supine position, falls due to the knees giving way, and difficulty raising the arms above the shoulders.

Sensory Symptoms

A slow, insidious onset sensory neuropathy typically shows a stocking-and-glove distribution in the distal extremities.

Sensory symptoms may be negative or positive, diffuse or focal.

• Negative sensory symptoms include feelings of numbness or deadness, which patients may describe as being akin to wearing gloves or socks. Loss of balance, especially with the eyes closed, and painless injuries due to loss of sensation are common.
• Positive symptoms may be described as burning, prickling pain, tingling, electric shock–like feelings, aching, tightness, or hypersensitivity to touch.

Diagnostic Procedures

Testing includes assessment of gross light touch and pinprick sensation. The first clinical sign that usually develops in diabetic symmetrical sensorimotor polyneuropathy is reduction of vibratory and pinprick sensation over the toes. As disease progresses, the level of decreased sensation may move upward into the legs and then from the hands into the arms, a pattern often referred to as "stocking and glove" sensory loss. Very severely affected patients may lose sensation in a "shield" distribution on the chest.

Vibratory sense in the feet is tested with a 128-Hz tuning fork placed at the base of the great toenail.

Deep tendon reflexes are commonly hypoactive or absent.

Outcome Measures

add links to outcome measures here (see Outcome Measures Database)

Management / Interventions

Medical Management of Pain in Diabetic Neuropathy

Anticonvulsants:
Gabapentin
Pregabalin
Valproate

Antidepressants: 
Amitriptyline
Duloxetine
Venlafaxine
Opioids
Dextromethorphan
Morphine sustained release5
Oxycodone
Tapentadol
Tramadol

Others
Topical nitrate sprays
Capsaicin cream

Physiotherapeutic Management of Pain in Diabetic Neuropathy

Evidence has been provided for:
Transcutaneous Nerve Stimulation (TENS)
Static magnetic field therapy
Low-intensive laser therapy
Monochromatic infrared light

Differential Diagnosis

Other possible causes of neuropathy include:
Toxins (eg, alcohol, occupational, vitamin B6)
medications (eg, amiodarone)
Hypothyroidism
Pernicious anaemia
Malignancies
Amyloidosis
Collagen vascular disease
Neurosarcoidosis.
Tabes dorsalis
AIDS.
Spinal cord disease
Cauda equina syndrome.

Key Evidence

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Resources

add appropriate resources here

Recent Related Research (from Pubmed)

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References

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