W10 - Diabetic Polyneuropathy

Question 1

Briefly define the term “Diabetic Polyneuropathy”.

Answer 1

The most common symptomatic complication of diabetes resulting from a combination of microvascular disease and hyperglycaemia and characterized by numbness and paraesthesia in the distal lower limb insidiously progressing proximally. The severity and progression is dependent on the degree of glycaemic control in both T1DM and T2DM.


Question 2

Describe the “typical” patient who is affected by:

• Diabetic polyneuropathy
• Diabetic mononeuropathy

Answer 2

Diabetic polyneuropathy - Typical patient would have poorly controlled T2DM for many years

Diabetic mononeuropathy - Typical patient would have mild (or undiagnosed) T2DM,. Many different types:

• Cranial neuropathies (CN III & VI commonly affected)
• Assymetrical proximal lower-limb neuropathy
• Truncal mononeuropathy (middle-aged patients)

Question 3

Describe the clinical manifestations of diabetic neuropathy that affects:

• Mixed diameter nerve fibres
• Small diameter nerve fibres

Answer 3

Mixed diameter nerve fibres:

• Loss of proprioception
• Loss of vibration sense
• Loss of light touch
• Loss of DTRs
• Abnormal nerve conduction studies


Small diameter nerve fibres:

• Burning or lancinating pain
• Hyperalgesia
• Paraesthesia and dysesthesia
• Decreased pain and temp perception
• Visceral pain perception deficits
• Foot ulceration

Question 4

What is “Diabetic Mononeuropathy”?

Answer 4

Common presenting symptom in patients with undiagnosed or mild T2DM that is usually caused by vasculitis characterised by burning/lancinating pain affecting one nerve at a time (may affect other nerves as disease progresses)

Question 5

Discuss the typical clinical manifestations of diabetic mononeuropathy affecting the oculomotor nerve (CN III).

Answer 5

Acute onset of Ssx:

• HA (retroorbital, frontal)
• Paralysis of extraocular muscles (supplied by CN III) - All except lateral rectus and superior oblique
• Pupillary function usually spared
• Spontaneous recovery in several weeks

Question 6

Discuss the prognosis of Diabetic Mononeuropathy.

Answer 6

• Good prognosis
• Diabetic mononeuropathy is a valuable symptom as it may be used to help diagnose cases of undiagnosed T2DM
• Education about modification of lifestyle factors (diet, exercise) often leads to spontaneous remission of mononeuropathy