Hypoglycaemia

Question 1

Definition of hypoglycaemia

Answer 1

Hypoglycaemia occurs when the blood glucose concentration falls below 4mmol/L

Question 2

Aetiology of hypoglycaemia

Answer 2

The main causes of hypoglycaemia are excessive amounts of insulin (exogenous or endogenous) or sulphonylurea treatment
◦ This is usually due to increased activity, missed meals or overdose

Other NON-DIABETIC causes include:
◦ Growth hormone deficiency due to hypopituitarism (results in failure of response to low blood glucose)
◦ Adrenal insufficiency due to Addison’s disease
◦ Alcohol use disorder
◦ Malnutrition
◦ Islet cell tumour (insulinoma) can lead to excess endogenous insulin
◦ Beta blockers, PPI, heparin etc

Question 3

Pathophysiology of hypoglycaemia

Answer 3

• The sympathoadrenal symptoms are as a result of an increased glucagon, epinephrine, cortisol and growth hormone in an effort to raise blood glucose levels
• E.g sweating, anxiety, nausea, tremor, hunger etc

Neuroglycopenic symptoms occur due to insufficient glucose supply to the brain despite the sympathoadrenal attempts to raise the blood sugar
◦ E.g blurred vision, dizziness, confusion, dysarthria, somnolence, convulsions, coma etc

Question 4

History and examination of hypoglycaemia

Answer 4

Autonomic/sympathoadrenal symptoms:
• Diaphoresis/sweating
• Anxiety
• Tremor
• Hunger
• Generalised tingling
• Nausea
• Palpitations

Neuroglycopenic symptoms:
• Confusion
• Irritability
• Blurred vision
• Drowsiness
• Seizures
• Coma
• Death

• Symptoms of underlying disease causing the hypoglycaemia (E.g hypotension, pigmentation (adrenal insufficiency))

Question 5

Risk factors for hypoglycaemia

Answer 5

• Exogenous insulin: incorrect dosage, decreased food intake, increased activity etc
• Hypoglycaemic medication: e.g Sulphonylurea
• Female
• Middle aged
• Insulinoma

Question 6

Investigations for hypoglycaemia

Answer 6

• Serum glucose:
◦ Measured every 6 hours from onset
◦ True hypoglycaemia= Whipple’s Triad: hypoglycaemia+reduced plasma glucose+resolution of symptoms post glucose rise
◦ Monitors are often not reliable at low levels
• LFTs, U&Es: exclude liver failure
• Cortisol, TSH levels etc
• May need 72 hour fasting: where glucose, insulin, C-peptide etc are monitored

Question 7

Treatment for hypoglycaemia

Answer 7

Insulin/Sulphonylurea cause:
1) Fix hypoglycaemia:
‣ If conscious and orientated: Give fast acting carbohydrate -> Orange juice, glucose gel
‣ If reduced consciousness: IV glucose
‣ If IV contraindicated or deteriorating: IM 1mg glucagon
2) Review and optimise treatment

Reactive hypoglycaemia (drop in glucose post-prandially):
1) Dietary changes: smaller but more frequent meals (high in protein and low in carbs, high fibre diet)

Insulinoma:
1) Surgical excision

Question 8

Complications and prognosis of hypoglycaemia

Answer 8

• Seizure
• Coma

Once underlying cause has been sorted out (hypoglycaemia inducing agent, insulinoma etc), there is very good prognosis