Reasoning GP · Algorithm · 1-page summary
Raised HbA1c or high blood glucose
For: adults with a raised HbA1c or glucose in primary care. Not for: children and young people (same-day paediatric pathway) or pregnancy (same-day antenatal diabetes team); known diabetes (see the protocols).
Core rule: before labelling type 2, check ketones if symptomatic, ask about weight loss and speed of onset, and in anyone 60+ with weight loss arrange urgent CT for pancreatic cancer.
0Stop — call 999 now
- DKA: vomiting, abdominal pain, Kussmaul breathing, drowsiness, or blood ketones ≥3.0 mmol/L (urine ≥2+) → 999. Glucose may be near-normal on an SGLT2 inhibitor.
- HHS: very high glucose, profound dehydration, confusion or drowsiness (mixed DKA/HHS occurs) → 999
- Sepsis or acute foot infection with systemic illness → 999
1Triage — confirm the diagnosis (NICE NG28)
| Result | Meaning → action |
|---|---|
| HbA1c ≥48 | Diabetes; repeat if asymptomatic; one result if symptomatic |
| HbA1c 42–47 | Non-diabetic hyperglycaemia → NDPP, annual HbA1c |
| Fasting ≥7.0 | Diabetes (confirm if asymptomatic) |
| Random ≥11.1 | Diabetes only with symptoms |
HbA1c unreliable → use glucose: rapid onset, suspected type 1, pregnancy, anaemia, haemolysis, haemoglobinopathy, transfusion, advanced CKD, steroids.
2Screen — serious causes
- Possible type 1 / LADA — weight loss, ketones, rapid onset, young or low BMI, any age → Same-day diabetes team. Ketones 1.6–2.9 → Same-day
- Pancreatic cancer (NG12) — 60+ with new diabetes and weight loss → Urgent CT abdomen (direct access).
- Pregnant with raised glucose → Same-day antenatal diabetes team.
- Active foot disease → Same-day foot protection/MDT service.
3Assess
☐ Glucose + blood ketones if symptomatic ☐ Weight, BMI, BP, feet ☐ U&E/eGFR, ACR, lipids, LFTs, FBC ☐ QRISK3 ☐ Drugs: steroids, antipsychotics ☐ Autoimmunity, family history, pancreatitis, alcohol
Targeted: GAD antibodies (do not wait for them), ferritin, Cushing's tests. Eye screening referral at diagnosis.
4Classify — only if blocks 0–2 are negative
- Type 2 (commonest) — gradual, overweight, family history, no ketones → block 5.
- Drug-induced — steroids, antipsychotics → evening glucose, review drug.
- MODY — young, non-obese, multigenerational family history → diabetes team.
- Pancreatic / endocrine — pancreatitis, haemochromatosis, Cushing's → targeted tests.
- Stress hyperglycaemia — acute illness, normal HbA1c → recheck at 3 months.
- Uncertain — unwell or ketotic: treat as type 1; otherwise discuss before labelling.
5Treat today — type 2; doses: NICE/SPC, BNF, local formulary
- MR metformin 500 mg daily with food, titrate weekly to 1–2 g (eGFR ≥30), then add an SGLT2 inhibitor once tolerated (NICE NG28 2026).
- Before the SGLT2i: previous DKA, dehydration, ketogenic diet; not while unwell; ketone and sick-day advice. Caution in frailty.
- Established CVD: add semaglutide up to 1 mg weekly. Atorvastatin 20 mg if QRISK3 ≥10%.
- 42–47: no routine medication — Diabetes Prevention Programme, lifestyle.
6Refer routinely and review
- Everyone: structured education within 3 months; eye screening at diagnosis.
- Diabetes team (routine): possible MODY, pancreatic or difficult steroid-induced diabetes. Endocrinology: suspected Cushing's.
- Review: metformin tolerance within 2–4 weeks; HbA1c at 3 months.
7Never reassure by
- Age or BMI — type 1 and LADA occur in overweight adults.
- A normal glucose on an SGLT2 inhibitor — check ketones.
- A normal HbA1c with rapid symptoms, anaemia or pregnancy.
- One borderline HbA1c in an asymptomatic person (repeat it).
- "Start metformin and see in 3 months" in a 60+ person losing weight.
- A capillary meter reading as a diagnosis.
8Safety-net — say it, then document it
999 “If you start vomiting, get tummy pain, very fast or deep breathing, or become drowsy or confused, call 999.” Same-day “Very thirsty, passing lots of urine and losing weight, or can't keep fluids down — contact us the same day; stop the flozin and metformin until eating and drinking again.”
Remote consultation with any 999 feature → convert to a 999 call. Ketones or tablet failure at any point → rethink the type.
✓Safe to leave primary care only if — all five, documented
No block 0–2 feature; ketones checked if symptomatic
Diagnosis confirmed by the right test
Type considered; NG12 flag checked if 60+
DKA check before SGLT2i; sick-day advice
Education, eyes, review and safety-net recorded
Summary of the full Reasoning GP hyperglycaemia algorithm, which holds the history, differential, investigations, lifestyle and evidence. Sources: NICE NG28 (updated February 2026), NG17, PH38, NG12 (suspected cancer, updated April 2026), NG3; JBDS DKA/HHS; MHRA. Clinical reference — follow local diabetes pathways and check doses in the current BNF and SPC.