Background Information
Definition
Hypoglycaemia is defined as blood glucose <4.0 mmol/L
Aetiology
Important causes: [Ref]
- Adrenal insufficiency
- Insulinoma
- Alcohol intoxication
- Critical illness (e.g. sepsis, end-stage liver failure)
- Medications
- Certain diabetes medications (insulin and sulfonylurea mainly)
- Beta-blocker toxicity
- Quinine toxicity
- Genetic disorders like glycogen storage diseases
Hypoglycaemia most commonly occurs in the context of diabetes, especially in patients treated with insulin or other hypoglycaemia-inducing medications like sulfonylureas
Diagnosis
Clinical Features
Clinical features of hypoglycaemia can be grouped as following: [Ref]
| Category | Clinical features |
|---|---|
| Autonomic symptoms (usually seen in <4 mmol/L) |
|
| Neuroglycopaenic symptoms (usually seen in <3 mmol/L) |
|
Investigation and Diagnosis
2 main tests are used to diagnose hypoglycaemia:
- Finger-prick blood glucose test: a quick bedside tool to measure blood glucose
- Serum glucose measurement: more accurate
The Whipple’s triad is used to diagnose true hypoglycaemia:
- Hypoglycaemia features (see above)
- Documented low serum glucose at the time of symptoms
- Relief of symptoms after glucose correction
Management
Blood Glucose ≥4.0 mmol/L
If there are symptoms of hypoglycaemia but blood glucose >4.0 mmol/L → treat with carbohydrate snack or normal meal (if due).
Blood Glucose <4.0 mmol/L
Conscious and Able to Swallow
1st line: oral fast-acting carbohydrate
- Glucose gel 40% (2 tubes) is preferred in those who are not capable and not cooperative (e.g. confused, disoriented, aggressive)
- Quick acting carbohydrate (e.g. glucose tablets) or 150-200 mL of pure fruit juice is preferred in those who are conscious and orientated
- Once blood glucose >4 mmol/L → provide a long-acting carbohydrate
Examples include:
- 2 biscuits
- 1 slice of bread
- 200-300 mL of normal milk
- Normal carbohydrate-containing meal (if due)
Repeat up to 3 times (15 min apart), then if no response → give IM glucagon or IV glucose infusion
Avoid chocolate and biscuits as they have a lower sugar content, and their high fat content may delay stomach emptying.
Unconscious / Unable to Swallow
1st line (IV access present): IV glucose infusion (100 mL of 20% dextrose or 200 mL of 10% dextrose over 15 min)
- If no IV access: glucagon IM (1 mg)
- Re-check glucose level after 10 min, and repeat treatment if necessary
- Once blood glucose >4 mmol/L → provide a long-acting carbohydrateExamples include: - 2 biscuits - 1 slice of bread - 200-300 mL of normal milk - Normal carbohydrate-containing meal (if due)
Do NOT omit subsequent insulin doses. The insulin regimen should be reviewed.
References
NICE BNF Treatment summaries. Hypoglycaemia
JBDS 01 The Hospital Management of Hypoglycaemia in Adults with Diabetes Mellitus