Hypoglycaemia
Concise, ED‑focused summary of recognition and initial management. Hypoglycaemia is a potentially life‑threatening low blood‑glucose state that requires rapid identification and reversal to prevent brain injury or death (NICE; Resuscitation Council UK).
Definitions and diagnostic criteria
- Working thresholds vary between authorities: NICE commonly uses <3.5 mmol/L as a working definition; other sources use ≤3.9 mmol/L and Diabetes UK advise maintaining ≥4.0 mmol/L for people with diabetes.
- In neonates a level ≤2.6 mmol/L is widely used to confirm hypoglycaemia; 2.6-3.5 mmol/L is often considered borderline (NICE NG17/NG18).
- True hypoglycaemia = Whipple’s triad: (1) symptoms/signs consistent with low glucose; (2) documented low plasma glucose when symptomatic; (3) symptomatic relief after glucose correction.
- Practical point: if a patient is unwell or perfusion is poor, capillary (finger‑prick) glucose can be unreliable - obtain a venous/arterial sample if accuracy is critical (Resuscitation Council UK).
Recognition: classic features
- Autonomic/adrenergic features: tremor, palpitations, sweating, anxiety, hunger, nausea; these may be blunted by beta‑blockers or in long‑standing diabetes.
- Neuroglycopenic features: confusion, drowsiness, visual disturbance, slurred speech, ataxia, focal deficits, seizures, coma.
- Atypical presentations: falls, confusion, stroke‑like symptoms (especially in the elderly); always check glucose early in any patient with reduced consciousness, collapse, seizure or suspected stroke.