Endocrine emergencies and electrolytes
Hypoglycaemia
Overview and approach
Hypoglycaemia has drug-related and non-drug causes; restore glucose promptly and explain why it occurred.
- In people with diabetes a hypo is usually a blood glucose below 4.0 mmol/L; frail or older people may have a higher threshold (5.0 to 6.0) because avoiding hypos is a greater priority (1).
- Causes (1): too much insulin or other glucose-lowering drug, less carbohydrate or a missed meal, alcohol without food, fasting, vomiting or diarrhoea, more activity than usual. Non-diabetes causes: fasting or post-prandial states, non-diabetic drugs, alcohol, hepatic, renal or cardiac failure; insulinoma (see Queensland CPC) (2).
Assessment and clinical features
Autonomic/neuroglycopenic symptoms, consciousness, swallowing safety, medicines, intake, alcohol and renal function.
- Autonomic: tremor, palpitations, anxiety, sweating, hunger, paraesthesia. Neuroglycopenic: dizziness, weakness, drowsiness, confusion, delirium, seizure, coma. Signs: sweating, pallor, tachycardia, raised BP, cognitive impairment.
- Some people have no symptoms; reduced awareness occurs with some medicines, frequent hypos, long diabetes duration and alcohol (1).
Differentials and investigations
Bedside glucose with confirmation when necessary; recurrent/unexplained episodes need targeted endocrine assessment.
- If glucose cannot be checked, treat as a hypo (1). Unexplained hypoglycaemia in a person without diabetes needs assessment for insulinoma, adrenal insufficiency and drugs (see Adrenal insufficiency page).
Management and follow-up
Oral carbohydrate only if safe to swallow; otherwise use trained local emergency treatment, then recheck and prevent recurrence.
- NDSS plan (1): if BGL below 4 mmol/L, give 15 g fast-acting carbohydrate (e.g. 5 jellybeans, 150 mL regular soft drink, 3 teaspoons sugar), recheck after 10 to 15 minutes and repeat until above 4; then give 15 g slow-acting carbohydrate if the next meal is more than 20 minutes away.
- Unconscious or unable to swallow: nothing by mouth, airway safe, recovery position, call 000; a trained person may give glucagon (1). Ambulance also if vomiting more than twice, unable to eat or drink, or BGL below 4 after 2 treatments (1).
- Review the cause and treatment with the diabetes team. Queensland criteria consider a major hypo needing third-party help a Category 1 referral (2).
Red flags and clinical pearls
Never give oral intake to an unprotected airway. Sulfonylurea or long-acting insulin exposure can cause recurrent hypoglycaemia requiring observation.
- Complications: arrhythmia, coma, injury such as when driving; these are relatively rare.
- ADS algorithm advises caution with sulfonylureas because of hypoglycaemia risk (3).
Last updated from Sen’s notes on 9 October 2026.