Diabetic neuropathy

Question 1

What is diabetic neuropathy?

Answer 1

“when diabetes causes damage to your nerves”
- Highly prevalent complication of T1 and T2 diabetes characterised by presence of signs of peripheral nerve dysfunction and/or autonomic nerve dysfunction
- Most common chronic complication of diabetes, caused by blockage of vasa nervorum

Question 2

What causes diabetic neuropathy?

Answer 2

• Chronic hyperglycaemia → glycation of axon proteins → neuropathy
• Primary cause of diabetic foot problems and ulceration, the leading causes of diabetes-related hospital admissions and non-traumatic amputation.

Question 3

What are the risk factors for diabetic neuropathy?

Answer 3

poorly controlled hyperglycaemia, older age (>70yrs old), prolonged duration of diabetes (>10yrs), tall stature, hypertension, dyslipidaemia, smoking

Question 4

What are the presenting symptoms/ signs of diabetic neuroptahy?

Answer 4

1. Peripheral Neuropathy:
   - Pain (Peripheral) → described as burning/sticking/aching. Often worse at night and may disturb sleep.
   - Loss of Sensation (Peripheral) → at early stage affects tips of toes or fingers. Eventually causes a symmetrical distal sensory loss in a ‘glove and stocking distribution’.
   - Dysesthesia (Peripheral) → burning sensation in feet
   - Reduced/Absent Ankle Reflexes (Peripheral)
   - Painless Injuries (Peripheral) → occur at pressure points. Infection is a common complication, followed by gangrene if vascular compromise.
   - Sensory loss and no motor loss.
2. Mononeuropathy → sudden motor loss (e.g. wrist drop, foot drop, 3rd nerve palsy - down and out eye)
3. Autonomic → resting tachycardia, urinary frequency/urgency/nocturia/incontinence/hesitancy/weak stream/retention, erectile dysfunction, constipation, difficulty swallowing, postural hypotension
   - Gastroparesis (GI Autonomic Neuropathy) ⇒ diabetics with upper GI symptoms and erratic glucose control due to gastric emptying dysfunction. Tx with metoclopramide (pro-kinetic that improves gastric emptying).

Question 5

What investigations are used to diagnose/ monitor diabetic neuropathy?

Answer 5

1. Test sensation using 10g monofilament
2. Fasting blood glucose
3. HbA1c → correlates with degree of glycaemic control
4. Tuning fork (decreased vibration sense), Pinprick assessment (decreased sensation)

Question 6

How is diabetic neuropathy managed?

Answer 6

1. Optimal glycaemic control
2. 1st line Tx if Painful → duloxetine, amitriptyline, gabapentin or pregabalin (if 1st line doesn’t work, try one of other 3 - duloxetine typically 1st line)
   - Avoid amitriptyline in patients with BPH as can cause urinary retention

Question 7

What complications may arise from diabetic neuropathy?

Answer 7

1. Foot wounds/ulcers (arterial, venous or neuropathic), wound infection/gangrene, amputation, silent MI, depression, death 
2. Neuropathic Ulcers⇒ typically over pressure pointssuch as plantar surface of metatarsal headand plantar surface of hallux. Painless with normal ABPI. Mx includes cushioned shoes to reduce callous formation.

Question 8

What areas of the body are commonly affected in neuropathy?

Answer 8

• Longest nerves supply feet – so more common in feet
• Commonly glove & stocking distribution (hands and lower limbs)– peripheral neuropathy
• Can be painful (worsens at night- can reduce sleep)
• Danger is that patients will not sense an injury to the foot (eg. stepping on a nail), so more likely to get diabetic foot ulcers

Question 9

What can increase the risk of foot ulcerations

Answer 9

• reduced sensation to feet (peripheral neuropathy)
• poor vascular supply to feet (peripheral vascular disease)