Diabetic Neuropathy

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management

Definition

Diabetic neuropathy is a progressive nerve disorder caused by prolonged hyperglycaemia, leading to damage in the peripheral and autonomic nervous system. It is a common complication of diabetes mellitus.

Aetiology

Diabetic neuropathy results from long-term exposure to high blood glucose levels, leading to nerve damage. Other contributing factors include:

  • Metabolic disturbances (oxidative stress, inflammation).
  • Vascular damage impairing blood supply to nerves.
  • Accumulation of advanced glycation end products (AGEs).
  • Autoimmune responses contributing to nerve injury.

Pathophysiology

  • Hyperglycaemia causes direct nerve toxicity by increasing oxidative stress and inflammation.
  • Damage to small blood vessels supplying nerves results in ischaemia.
  • Impaired nerve regeneration leads to progressive sensory and motor dysfunction.
  • Autonomic dysfunction affects involuntary bodily functions (e.g., heart rate, digestion).

Risk factors

  • Poor glycaemic control.
  • Long duration of diabetes.
  • Hypertension and dyslipidaemia.
  • Smoking and excessive alcohol intake.
  • Obesity and sedentary lifestyle.

Signs and symptoms

Diabetic neuropathy presents in different forms, depending on the affected nerves.

1. Peripheral Neuropathy (Most Common):

  • Symmetrical "glove and stocking" sensory loss.
  • Tingling, burning, or sharp pain in feet and hands.
  • Reduced vibration, temperature, and pain sensation.
  • Weakness and muscle wasting in advanced cases.

2. Autonomic Neuropathy:

  • Postural hypotension (dizziness when standing).
  • Gastroparesis (delayed gastric emptying, nausea).
  • Bladder dysfunction (urinary retention, incontinence).
  • Erectile dysfunction in men.

3. Proximal Neuropathy (Diabetic Amyotrophy):

  • Severe pain and weakness in thighs, hips, and buttocks.
  • Difficulty rising from a seated position.
  • Unilateral or bilateral muscle wasting.

4. Focal Neuropathy:

  • Sudden weakness in a single nerve (e.g., cranial nerves causing double vision, Bell’s palsy).
  • Entrapment neuropathies (e.g., carpal tunnel syndrome).

Investigations

  • Clinical assessment: sensory testing using monofilament, vibration, and pinprick tests.
  • Blood glucose and HbA1c: assess glycaemic control.
  • Nerve conduction studies (NCS): confirm nerve damage and severity.
  • Electromyography (EMG): assess muscle involvement.
  • Autonomic function tests: includes postural blood pressure measurement, heart rate variability tests.
  • Urinalysis: to rule out urinary infections in autonomic neuropathy.

Management

1. Glycaemic Control:

  • Aim for an HbA1c target of <7% (or as per individualised goal).
  • Use of oral hypoglycaemics (e.g., metformin) or insulin if required.
  • Lifestyle modifications (diet, exercise, smoking cessation).

2. Pain Management:

  • First-line: amitriptyline, duloxetine, pregabalin, or gabapentin.
  • Second-line: tramadol or capsaicin cream for localised pain.
  • Non-pharmacological options: TENS therapy, physiotherapy.

3. Autonomic Neuropathy Treatment:

  • Postural hypotension: compression stockings, fludrocortisone, midodrine.
  • Gastroparesis: prokinetics (e.g., domperidone, erythromycin).
  • Bladder dysfunction: intermittent catheterisation, anticholinergics.
  • Erectile dysfunction: phosphodiesterase inhibitors (e.g., sildenafil).

4. Foot Care and Prevention:

  • Regular foot checks for ulcer prevention.
  • Proper footwear to prevent pressure sores.
  • Education on daily foot inspection.
NeurologymypanotesDiabetic Neuropathy