Hypoglycaemia

Question 1

What is it?

Answer 1

Hypoglycaemia is very common among patients with diabetes mellitus, usually secondary to insulin or certain hypoglycaemic agents (e.g. suphonylureas). Hypoglycaemia may also occur in patients without diabetes mellitus. In this situation, hypoglycaemia is uncommon and may occur due to a range of abnormalities, some very rare.

Hypoglycaemia is generally defined as an abnormally low blood glucose concentration (< 4.0 mmol/L).

Normal fasting range: 4.0-5.4 mmol/L
Normal post-prandial range: 4.0-7.8 mmol/L (up to two hours after eating)
Clinically significant hypoglycaemia is generally defined as < 3.0 mmol/L. At this level, hypoglycaemia can be associated with serious immediate and long-term consequences. A blood glucose concentration < 3.0 mmol/L rarely occurs in the absence of diabetes mellitus.

Question 2

Causes?

Answer 2

Diabetes
Alcohol
Malnourishment
Islet beta tumours

Question 3

History

Answer 3

Tremor
Palpitations
Anxiety
Sweating
Hunger
Paraesthesia
Dizziness
Weakness
Drowsiness
Confusion
Altered mental status
Seizure

Question 4

Diagnosis?

Answer 4

The diagnosis of hypoglycaemia is based on capillary blood glucose or serum blood glucose measurements.

72 hour fast (see below)
Glucose
Insulin: will be inappropriately high in endogenous hyperinsulinaemia
C-peptide: short polypeptide that forms part of proinsulin. It is cleaved to form insulin. Inappropriately high in endogenous hyperinsulinaemia.
Pro-insulin: prohormone precursor released by beta cells. Cleaved to form insulin and C-peptide.
Sulfonylurea screen: used to detect accidental or malicious use of oral hypoglycaemic agents
Beta-hydroxybutyrate (BHOB): a blood ketone. Levels should be low in the context of hyperinsulinaemia because of the anti-ketone effect of insulin.

Question 5

Management ?

Answer 5

Alert and hypoglycaemia
Give an oral glucose load: for example 120 mls of lucozade, single dose of hypostop or glucogel orally.
Give a more complex carbohydrate meal: oral glucose load will only last an hour
Monitor capillary blood glucose: usually 1-2 hourly until stable
Consider intravenous dextrose (5-10%): if persistent hypoglycaemia, whilst investigating suspected cause
Determine underlying cause

Coma and hypoglycaemia
ABCDE assessment: if any concerns, call senior help urgently
Establish intravenous access
Give an intravenous load of glucose: 50 mls 50% dextrose, 100 mls 20% dextrose or 200 mls 10% dextrose (often depends on stock available)
Consider 1 mg glucagon (SC/IM/IV): particularly if difficult to establish access. Remember, unlikely to be effective if poor glycogen stores (e.g. malnourished, hepatic disease).
Reassess: should see rapid improvement in symptoms (i.e. < 10 minutes) if hypoglycaemia is the cause of low GCS.
Consider starting intravenous glucose infusion: for example, 1 litre 10% dextrose.
Continue monitoring: usually capillary blood glucose 1-2 hourly until stable
Determine underlying cause