Endocrinology · core
Unconscious hypoglycaemia
An unconscious adult with hypoglycaemia and intravenous access is treated with intravenous glucose — 150 to 200 mL of 10% glucose, or 75 to 100 mL of 20% glucose. Oral carbohydrate is unsafe. Glucagon is the no-IV-access alternative, not the first choice when a cannula is already in.
Why this is high-yield for the PLAB 1
PLAB 1 still catches doctors who remember the old 50 mL of 50% glucose, or who pour Glucogel into an unprotected airway. The BNF sequence is simple: if they cannot swallow, give IV glucose when you have a line; use IM glucagon only if you cannot get one.
The question
A 34-year-old man with type 1 diabetes is found unresponsive in the waiting room. His capillary glucose is 1.6 mmol/L. He is breathing and has a palpable pulse. There is no seizure activity. A 16-gauge cannula is in situ in the antecubital fossa. He has no glucagon kit with him. Staff have already given high-flow oxygen.
What is the most appropriate immediate treatment?
- A. Buccal glucose gel
- B. Intravenous glucose 10% 150–200 mL (or 20% 75–100 mL)
- C. Intramuscular glucagon 1 mg as first-line despite the cannula
- D. 50 mL of 50% intravenous glucose
- E. Subcutaneous insulin lispro 4 units
Reveal the worked answer
Correct answer: B. Intravenous glucose 10% 150–200 mL (or 20% 75–100 mL)
A — Buccal or oral carbohydrate is for the conscious patient who can swallow. In an unresponsive adult it risks aspiration and does not reliably raise plasma glucose.
B (correct) — This is the BNF regimen for unconscious hypoglycaemia when intravenous access is available. Recheck glucose after 10 minutes and repeat if it remains low. Then give longer-acting carbohydrate once he is awake.
C — Glucagon 1 mg IM is correct when there is no IV access. It is slower and can fail in people with low glycogen stores. A working cannula means intravenous glucose first.
D — Concentrated 50% glucose is no longer first-line in UK practice. It extravasates badly and is not the BNF adult recommendation. Use 10% or 20% glucose in the volumes above.
E — Insulin lowers glucose further. This stem is hypoglycaemia, not DKA or hyperglycaemia.
Clinical pearl. Cannot swallow + a cannula = IV 10% (or 20%) glucose. Glucagon is the backup when you have no line. Never 50% as a habit.
MLA Content Map. Acute and emergency care · Hypoglycaemia
Guideline. BNF treatment summary — Hypoglycaemia (BNF Hypoglycaemia)
Key facts to remember
- First-line treatment of unconscious adult hypoglycaemia when IV access is present?
- IV glucose 10% 150–200 mL, or 20% 75–100 mL.
- When is intramuscular glucagon first-line in hypoglycaemia?
- When the patient cannot take oral carbohydrate and there is no intravenous access.
- Why avoid 50% glucose as routine first-line treatment?
- It is no longer the BNF first-line adult regimen and carries a high extravasation injury risk.
- Why not give glucose gel to an unconscious patient?
- Aspiration risk, and it does not reliably correct severe hypoglycaemia.
Frequently asked questions
What is the first-line treatment for unconscious hypoglycaemia?
If a cannula is in, give intravenous 10% or 20% glucose in BNF volumes. If there is no IV access, give intramuscular glucagon 1 mg in adults.
Is 50 mL of 50% glucose still acceptable?
It is not the current BNF first-line adult recommendation. Prefer 10% or 20% glucose. 50% is reserved for specific settings and has a high extravasation risk.
What do you do after the glucose comes up?
Give longer-acting carbohydrate once the patient can swallow, look for the cause, and do not discharge until they are stable and have a plan.
Related reading
Related learning paths
Educational content for exam preparation — always follow your local guidelines in practice. See our editorial standards.