Recurrent Hypoglycaemia
Recurrent Collapse • Hypoglycaemia • Insulinoma • MRCP (UK) PACES
A structured MRCP (UK) PACES approach to patients presenting with recurrent collapse caused by hypoglycaemia. Learn how to recognise Whipple's triad, distinguish diabetic from non-diabetic hypoglycaemia, identify insulinoma and endocrine disorders, and counsel patients regarding investigations, treatment and prevention.
At a Glance
Red Flags
PACES Approach
Causes of Hypoglycaemia
Insulin • Sulfonylureas
Insulinoma • Adrenal insufficiency
Advanced chronic kidney disease
Starvation • Alcohol • Poor intake
Sepsis • Liver failure
MEN1-associated insulinoma
Overview
Recurrent hypoglycaemia is a medical emergency that commonly presents with dizziness, sweating, tremor, collapse or loss of consciousness. During the MRCP (UK) PACES Long Clinical Consultation, candidates should confirm that true hypoglycaemia is present by establishing Whipple's triad, identify the underlying cause and distinguish diabetic from non-diabetic hypoglycaemia. Drug-induced hypoglycaemia remains the commonest cause, but insulinoma, adrenal insufficiency, renal failure and MEN1 syndrome must also be considered. :contentReference[oaicite:1]{index=1}
Focused History
Characterise the Episode
- What happened during the collapse?
- Were you standing, exercising or fasting beforehand?
- Did anyone witness the episode?
- How long did it last?
- How quickly did you recover?
- Any injuries following the collapse?
Symptoms Suggesting Hypoglycaemia
- Sweating.
- Tremor.
- Palpitations.
- Feeling cold.
- Intense hunger.
- Blurred vision.
- Light-headedness.
- Confusion or altered behaviour.
Establish Whipple's Triad
- Typical symptoms of hypoglycaemia.
- Documented low plasma glucose.
- Resolution of symptoms after glucose administration.
Diabetes History
- Type and duration of diabetes.
- Recent HbA1c.
- Current insulin or oral hypoglycaemic therapy.
- Recent dose changes.
- Missed meals or poor dietary intake.
- Recent excessive exercise.
- Alcohol intake.
Screen for Non-diabetic Causes
- Weight gain suggesting insulinoma.
- Symptoms of adrenal insufficiency (postural dizziness, weight loss, hyperpigmentation).
- Chronic kidney disease.
- Liver disease.
- Recent severe infection.
- Recent steroid withdrawal.
Screen for MEN1 Syndrome
- Recurrent renal stones.
- Symptoms of hypercalcaemia.
- Headache.
- Visual disturbance.
- Family history of endocrine tumours.
Drug and Social History
- Insulin.
- Sulfonylureas.
- Beta-blockers.
- Alcohol consumption.
- Occupation and driving status.
Focused Examination
- Measure capillary blood glucose immediately.
- Look for finger-prick marks suggesting insulin use.
- Assess body mass index.
- Measure lying and standing blood pressure.
- Look for hyperpigmentation suggesting Addison disease.
- Assess hydration status.
- Perform fundoscopy for diabetic retinopathy.
- Examine for peripheral neuropathy.
- Look for features of chronic kidney disease.
- Assess for proximal muscle weakness.
Differential Diagnosis
Investigations
Immediate Investigations
- Capillary blood glucose.
- Venous plasma glucose.
- ECG.
- Basic blood tests including renal function.
Biochemical Investigation During Hypoglycaemia
- Insulin.
- C-peptide.
- Proinsulin.
- Sulfonylurea screen.
- Beta-hydroxybutyrate.
Further Investigations
- 72-hour supervised fast when insulinoma is suspected.
- Short Synacthen test for adrenal insufficiency.
- MRI or CT pancreas.
- Pituitary MRI if MEN1 is suspected.
- Parathyroid hormone and serum calcium.
- Thyroid function tests.
PACES Tip: Always obtain blood for glucose, insulin and C-peptide during a hypoglycaemic episode. Samples taken after glucose replacement may no longer identify the underlying cause. :contentReference[oaicite:1]{index=1}
Diagnosis
Recurrent Hypoglycaemia
The combination of recurrent neuroglycopenic symptoms, documented low plasma glucose and relief after glucose replacement fulfils Whipple's triad, confirming true hypoglycaemia. The next step is identifying the underlying cause, which may include diabetes treatment, insulinoma, adrenal insufficiency, chronic kidney disease or MEN1 syndrome. :contentReference[oaicite:2]{index=2}
Explaining to the Patient
"Your symptoms strongly suggest episodes of low blood sugar, known as hypoglycaemia. This can happen for several different reasons, including diabetes medication, hormone problems or, more rarely, a tumour producing excess insulin. We need to confirm the diagnosis with blood tests taken during an episode, identify the underlying cause and treat it to prevent future attacks."
Management
Examiner's Corner
What is Whipple's Triad?
- Symptoms consistent with hypoglycaemia.
- Documented low plasma glucose.
- Resolution of symptoms after correction of hypoglycaemia.
What causes hypoglycaemia in non-diabetic patients?
- Insulinoma.
- Adrenal insufficiency.
- Critical illness including sepsis.
- Advanced liver disease.
- Advanced chronic kidney disease.
- Alcohol-related hypoglycaemia.
- Factitious insulin or sulfonylurea use.
How is insulinoma diagnosed?
- Document endogenous hyperinsulinism during hypoglycaemia.
- Raised insulin with inappropriately elevated C-peptide.
- 72-hour supervised fast is the diagnostic standard.
- Localise the tumour using CT, MRI or endoscopic ultrasound.
What is hypoglycaemia unawareness?
- Loss of early warning symptoms due to recurrent hypoglycaemia.
- Common in long-standing insulin-treated diabetes.
- Increases the risk of severe hypoglycaemia.
- Requires adjustment of glycaemic targets and specialist review.
When should MEN1 syndrome be considered?
- Confirmed insulinoma, particularly in younger patients.
- Multiple endocrine tumours.
- Hyperparathyroidism.
- Pituitary adenoma.
- Family history of MEN1.
Common PACES Viva Questions
- What is Whipple's triad?
- How would you manage severe hypoglycaemia?
- Which medications commonly cause hypoglycaemia?
- How do you investigate insulinoma?
- What advice should be given regarding driving?
- What is hypoglycaemia unawareness?
- Which endocrine disorders cause recurrent hypoglycaemia?
Important Clinical Pearls
- Always confirm true hypoglycaemia before extensive investigation.
- Drug-induced hypoglycaemia is the commonest cause.
- Obtain insulin and C-peptide samples during the hypoglycaemic episode.
- Insulinoma should be considered in recurrent fasting hypoglycaemia.
- Repeated severe hypoglycaemia requires urgent specialist assessment.
Pathfinder Pearls
Common Pitfalls
- Assuming every collapse is neurological rather than checking blood glucose immediately.
- Failing to establish Whipple's triad before pursuing extensive investigations.
- Taking insulin and C-peptide samples after glucose administration.
- Missing insulinoma in a patient without diabetes.
- Ignoring adrenal insufficiency or severe systemic illness.
- Failing to advise patients about driving restrictions after severe hypoglycaemia.
- Not recognising hypoglycaemia unawareness in insulin-treated diabetes.
Key Take-home Messages
- Confirm true hypoglycaemia by establishing Whipple's triad.
- Treat severe hypoglycaemia immediately before pursuing further investigations.
- Obtain critical blood samples during the hypoglycaemic episode whenever possible.
- Drug-induced hypoglycaemia is most common, but insulinoma and endocrine disorders should be considered in non-diabetic patients.
- Patient education, medication review and prevention of recurrence are essential components of long-term management.
Master MRCP (UK) PACES Long Clinical Consultations
Develop a structured approach to endocrine emergencies, diabetes and metabolic medicine through examiner-led teaching, realistic mock consultations, personalised feedback and the PACES Pathfinders Learning Library.