Reasoning GP · Algorithm · 1-page summary
Hypoglycaemia in adults
For: adults with diabetes on insulin or a sulfonylurea with a low glucose, and adults without diabetes with suspected hypoglycaemia, in hours or OOH. Not for: children (paediatric pathways). Ongoing glucose management: the type 1 and type 2 diabetes protocols.
Core rule: in diabetes, treat any glucose <4.0 mmol/L now — fast glucose if they can swallow, glucagon and 999 if they cannot — then find the cause. A sulfonylurea hypo can recur for 24–36 hours.
0Stop — call 999 now — treat first, never delay treatment to take samples
- Unconscious, seizing or unable to swallow (level 3) → 999 Nothing by mouth. IM glucagon 1 mg (or nasal glucagon 3 mg) by a trained carer or clinician; recovery position.
- Glucose still <4.0 mmol/L after 3 treatment cycles → glucagon if available and 999. Consciousness or focal signs not recovering once glucose is corrected → 999: think stroke, seizure, intracranial bleed, sepsis, intoxication.
- Hypo with Addisonian features (pigmentation, postural hypotension, low sodium, high potassium) → 999; emergency hydrocortisone per the local adrenal-crisis protocol, plus glucose.
- While waiting: IV glucose only by a skilled professional with IV access (100 mL 20% or 200 mL 10% over 15 min, per local protocol). Reassess at about 10 min; keep monitoring.
1Triage by severity — capillary glucose first
| Level | Action |
|---|---|
| 1 · 3.0–3.9, alert | 15–20 g fast-acting glucose; recheck at 10–15 min |
| 2 · <3.0, can swallow | 20 g fast glucose; can't eat solids → glucose gel into cheek |
| 3 · needs another person | Unable to swallow → glucagon + 999 (block 0) |
| No diabetes | Not from a meter: Whipple's triad, lab glucose |
2Screen — one row is enough
- Sulfonylurea hypo: severe, recurrent, needed glucagon/IV glucose, long-acting or MR, renal impairment, frail, uncertain overdose → Same-day hospital observation
- Hypo with a focal neurological deficit (stroke mimic) → Same-day medical
- Recurrent spontaneous hypo, no diabetes, no obvious cause → Urgent endocrinology (999 if unwell). If safe, in the episode: lab glucose, insulin, C-peptide, proinsulin, β-hydroxybutyrate, sulfonylurea screen.
- No diabetes but access to insulin or a sulfonylurea → consider error or deliberate exposure (C-peptide suppressed = exogenous insulin); safeguarding if a child or vulnerable adult.
- Care-home resident, recurrent hypos on insulin or sulfonylurea, no review >6 months → Same-day review
3Assess — once glucose is corrected
☐ GCS, focal signs, pulse, postural BP ☐ Addison's signs, liver disease, injection sites (lipohypertrophy) ☐ Timing: fasting, post-meal, nocturnal ☐ Awareness: Gold score ≥4 = impaired ☐ Lab glucose, HbA1c, eGFR, LFTs; cortisol ± ACTH if targeted
Not in primary care: 72-hour fast, mixed-meal test, imaging.
4Classify — find the cause
- Insulin — dose, missed meal, exercise, alcohol. Timing points to the dose: late-morning hypo = breakfast rapid-acting; nocturnal = basal.
- Sulfonylurea — risk rises with CKD, older age, frailty and poor intake; glibenclamide is the most prolonged.
- Alcohol — 6–12 h after heavy drinking. Impaired awareness — repeated hypos, neuropathy, beta-blockers.
- No diabetes — fasting (insulinoma, Addison's, alcohol); after meals (reactive, post-bariatric); sepsis or liver failure.
- Uncertain — confirm with a lab glucose; consider anxiety, arrhythmia or TIA.
5Treat today — doses: NICE/SPC, BNF, local formulary
- Can swallow: glucose tablets or 150–200 mL fruit juice; recheck at 10–15 min, repeat up to 3 times; then bread, two biscuits or the next meal. No chocolate. On acarbose: glucose only.
- Review the drug: adjust the responsible insulin dose per the diabetes-team plan. Sulfonylurea: lowest effective dose or stop; avoid glibenclamide.
- Type 1: never stop basal insulin. Not eating on a sulfonylurea → withhold or seek advice.
- Prepare: always carry glucose; glucagon at home for type 1 and train carers; give and document DVLA advice.
6Refer routinely
- Diabetes team / DSN: any level 3 episode, Gold score ≥4, recurrent hypos on insulin, HbA1c too low on insulin or a sulfonylurea.
- CGM per NICE: all adults with type 1; type 2 on multiple daily insulin with recurrent or severe hypos, impaired awareness, or unable to finger-prick.
- Post-bariatric hypos → Urgent endocrinology. Frail type 2 → relax HbA1c target individually.
7Never reassure by
- A sulfonylurea hypo corrected by one sugary drink — it can recur for 24–36 h.
- A capillary meter reading alone in someone without diabetes.
- "Just a hypo" when consciousness or focal signs do not recover after correction.
- No warning symptoms — age, beta-blockers and impaired awareness blunt them.
- A low HbA1c on insulin or a sulfonylurea — that is over-treatment.
- A glucagon response — less reliable after a sulfonylurea, fasting or alcohol.
8Safety-net — say it, then document it
999 “If they cannot swallow, are very drowsy, fitting or unconscious: nothing by mouth, give glucagon and call 999. Also call 999 if the glucose is still under 4 after three treatments.” Same day: “A hypo on gliclazide that needed help or keeps coming back needs a hospital check today.”
Driving: “Check your glucose before driving and every 2 hours. Never drive during or just after a hypo — wait until recovered and the DVLA waiting time has passed.” Diabetes team or DSN review after any severe or recurrent episode.
✓Safe to leave primary care only if — all five, documented
No block 0–2 row applies
Glucose ≥4.0 and longer-acting carbohydrate eaten
Cause found; insulin or sulfonylurea dose reviewed
Glucose, glucagon and DVLA advice given
Safety-net given; diabetes-team review if severe or recurrent
Summary of the full Reasoning GP hypoglycaemia algorithm, which holds the detail, examination, driving rules and evidence. Sources: JBDS hospital management of hypoglycaemia (2023); NICE NG17, NG28; DVLA Assessing fitness to drive; MHRA SGLT2 inhibitors; TREND-UK sick-day rules. Clinical reference — follow local emergency protocols and check doses: NICE/SPC, BNF.