Diabetic Neuropathy

Question 1

What is diabetic neuropathy (DN)?

Answer 1

Highly prevalent complication of diabetes (type 1 or type 2) and is characterised by the presence of symptoms and/or signs of peripheral nerve dysfunction and/or autonomic nerve dysfunction.

Question 2

What are the risk factors for DN?

Answer 2

• Poorlu controlled hyperglycaemia
• Prolonged duration of diabetes
• Older age (>70 Y)
• Tall stature
• Hypertension
• Dyslipidaemia with elevated triglycerides
• Co-existance of multiple CVD (type 2)

Question 3

What are the signs of DN?

Answer 3

Note: up to 50% of patients with DN may be completely asymptomatic.

• Reduced or absent reflexes (peripheral)
• Resting tachycardia (autonomic)
• Impaired heart rate variability (peripheral)

Question 4

What are the symptoms of DN?

Answer 4

Note: up to 50% of patients with DN may be completely asymptomatic.

• Pain (peripheral)
• Loss of sensation (peripheral)
• Dysaesthesia (peripheral)
• Painless injuries
• Urinary frequency, urgency, nocturia, incontinence, hesitency, weak stream or retention (autonomic)
• Erectile dysfunction (autonomic)

Question 5

What investigations should be ordered for DN?

Answer 5

• Clinical diagnosis
• Fasting blood glucoseH
• HbA1c
• Serum thyroid stimulating hormone
• Serum vitamin B12
• Electrolytes, urea and creatinine

Question 6

How is a clinical diagnosis of DN made?

Answer 6

Routine screening tests may exclude other common conditions. Diagnosis of peripheral neuropathy is often made on clinical grounds.

Question 7

What modalitities need to be assessed in DN?

Answer 7

Sensory loss is defined in terms of extent, distribution, and modality and involves assessment of:

• Pinprick sensation
• Light touch
• Vibration
• Joint position

Question 8

Why investigate using fasting blood glucose? And what may this show?

Answer 8

• Many patients who present with painful neuropathy may have diabetes without knowing it. In this circumstance, a fasting blood glucose may be performed.
• Diagnosis of diabetes mellitus (if not already known to be present).

Question 9

Why investigate using HbA1c? And what may this show?

Answer 9

• Many patients who present with painful neuropathy may have diabetes without knowing it. In this circumstance, HbA1c may be performed. Poorly controlled hyperglycaemia is associated with increased risk of neuropathy.
• Correlates with degree of glycaemic control.

Question 10

Why investigate serum-thyroid stimulating hormone? And what may this show?

Answer 10

• To exclude thyroid dysfunction.
• Normal.

Question 11

Why investigate serum vitamin B12? And what may this show?

Answer 11

• To exclude deficiency.
• Normal.

Question 12

Why investigate electrolytes, urea and creatinine? And what may this show?

Answer 12

• To exclude renal disease.
• Normal.

Question 13

Briefly describe the treatment options for DN

Answer 13

• Glycamic control and supportive measures
• Pain management
  
  • Pregabalin, duloxetine and gabapentin
  • Opioid analgesic
• Antidepressant

Question 14

What are the options for pain management in DN?

Answer 14

Pregabalin, duloxetine, and gabapentin are considered first-line pharmacotherapies for painful DN.

Opioid analgesics (e.g. tramadol) may be considered in a specialist setting, if other agents have failed, or if rescue therapy is required. They have significant adverse effects with long-term use; dependence may occur.

Question 15

When are antidepressants considered in managing DN?

Answer 15

Antidepressants may be used if there is no benefit from pregabalin or gabapentin and duloxetine. They may be used alone or in combination with pregabalin or gabapentin.

Tricyclic antidepressant (TCA), for example amitriptyline, imipramine and nortriptyline, are throught to be most effective.

Question 16

What complciations are associated with DN?

Answer 16

• Foot and wound ulcers
• Wound infection and gangrene
• Amputation

Question 17

What differentials should be considered for DN?

Answer 17

• Uraemia
• Cyanocobalamin deficiency
• Hypothyroidism

Question 18

How does DN and uraemia differ?

Answer 18

• Differentiating signs and symptoms: various signs associated with the primary cause for end-stage renal disease (ESRD) may be present. May co-exist with DN.
• Differentiating investigations: abnormal urea, creatinine, GFR consistent with ESRD.

Question 19

How does DN and cyanocabalamin deficiency differ?

Answer 19

• Differentiating signs and symptoms: poor nutrition, alcoholism, certain drugs (e.g., trimethoprim, methotrexate, phenytoin), pernicious anaemia, atrophic gastritis, malabsorption, or infection with Helicobacter pylori more likely to be present.
• Differentiating investigations: FBC reveals macrocytic anaemia and reduced serum vitamin B12 levels.

Question 20

How does DN and hypothyroidism differ?

Answer 20

• Differentiating signs and symptoms: fatigue, cold intolerance, weight gain, constipation, myalgia, menstrual irregularities, delayed relaxation of deep tendon reflexes, bradycardia (if severe).
• Differentiating investigations: thyroid-stimulating hormone elevated in primary hypothyroidism. Free serum thyroxine (T4) may be low.

Question 21

Briefly describe the screening for DN in type 1 diabetes

Question 22

Briefly descirbe the screening for DN in type 2 diabetes

Answer 22

*

Question 23

How is DN screening for in type 1 and type 2 diabetes?

Answer 23

Using symptoms and signs (simple clinical assessments include pinprick sensation, vibration perception [128-Hz tuning fork], light touch perception [10-g monofilament], ankle reflexes).