Synopsis
Recognise and treat low glucose promptly while finding the cause, preventing recurrence and preserving essential background diabetes therapy safely.
- Think ‘four is the floor’: a capillary reading below 4.0 mmol/L requires action in an adult inpatient even when symptoms are subtle or absent.
- Choose treatment by consciousness and swallow safety, not by the number alone; oral carbohydrate is unsafe in a drowsy, fitting or uncooperative patient.
- For a conscious cooperative adult, JBDS uses 15–20 g rapid-acting carbohydrate followed by a glucose recheck after 10–15 minutes and repeat treatment if still low.
- Once glucose is above 4.0 mmol/L and the person has recovered, give longer-acting carbohydrate or the planned meal and review the medicine that created risk.
- Sulfonylurea and long-acting insulin hypoglycaemia may recur for 24–36 hours, especially with renal impairment; a single normal result is not a discharge test.
- Glucagon may be less effective after repeated episodes, prolonged fasting, alcohol excess, liver disease or sulfonylurea exposure, so arrange reliable glucose delivery and monitoring.
- During an active intravenous insulin infusion, pause it while treating the low glucose and restart safely once corrected according to the indication and local chart.
- Document precipitant, severity, awareness, assistance required and prevention changes; provide driving advice when the event meets current DVLA relevance.
Key red flags
Sweating, tremor, hunger, palpitations, tingling or anxiety may precede cognitive impairment and provide a window for self-treatment when swallowing remains safe.
Irritability, bizarre behaviour, confusion, dysarthria, focal-looking weakness, seizure or reduced consciousness can mimic stroke or intoxication, so glucose belongs in every acute neurological assessment.
Renal decline, sulfonylurea use, long-acting insulin, administration error or reduced intake predicts recurrence and often warrants extended observation and specialist medication adjustment.
Persistent coma, focal deficit, fever, trauma, toxic exposure or failure to improve after glucose correction means another diagnosis must be assessed in parallel.
Investigation priorities
Identify a reversible cause of acute behavioural, neurological or autonomic symptoms at the bedside.
Management branches
Glucose is below 4.0 mmol/L and the adult is alert, cooperative and able to swallow safely.
- Give 15–20 g rapid-acting carbohydrate using a stocked option compatible with swallowing ability and any fluid or renal restriction, following the local JBDS-aligned chart.
- Recheck capillary glucose after 10–15 minutes; if it remains below 4.0 mmol/L, repeat the rapid treatment and reassess, using the escalation route if three cycles fail.
- After recovery, give a longer-acting carbohydrate snack or planned meal, resume appropriate diabetes treatment safely and investigate why supply and insulin action became mismatched.