Reasoning GP · Algorithm · 1-page summary
Glycosuria — glucose on a urine dipstick
For: adults and children with glucose on a dipstick, incidental, screening or symptomatic. Not for: monitoring known diabetes (urine glucose has no role) — use the type 1 and type 2 diabetes protocols. Pregnancy and children with suspected type 1 go to block 1.
Core rule: glycosuria is a dipstick clue, not a diagnosis — never diagnose or exclude diabetes on urine glucose; check a blood glucose, and blood ketones if symptomatic. The lean young person with thirst and weight loss has type 1 until proven otherwise.
0Stop — call 999 now — check capillary glucose and blood ketones first if you can
- Suspected DKA: blood ketones ≥3.0 mmol/L, vomiting, deep or fast breathing, drowsiness or confusion → 999 / immediate admission
- On an SGLT2 inhibitor (“flozin”) and unwell — nausea, vomiting, abdominal pain, tachypnoea: DKA with only moderately raised glucose → blood ketones urgently; suspected DKA → 999
- HHS: often older, marked hyperglycaemia, severe dehydration, altered cognition; no single glucose threshold → 999 / immediate admission
- While waiting: do not rely on urine ketones where blood ketones are available; do not start oral agents; never send home to await fasting bloods. Pregnant with suspected DKA → immediate admission (medical and obstetric care).
1Triage — unwell, ketotic or rapid weight loss?
| Who | Action |
|---|---|
| Child or young person | Suspected type 1 → Same-day paediatric diabetes team (NG18). No fasting glucose, HbA1c or OGTT first. |
| Adult, likely type 1 | Rapid osmotic symptoms, weight loss, ketosis or lean, but stable → Same-day diabetes team for insulin. No oral agents. |
| Pregnant | 2+ once, or 1+ on ≥2 occasions → consider 75 g OGTT (NG3). Triggers testing; does not diagnose. |
| Well | Laboratory plasma glucose and/or HbA1c (block 3). |
2Screen — serious causes behind the glucose
- Aged ≥60 with weight loss and new-onset diabetes (or diarrhoea, back or abdominal pain, nausea, vomiting, constipation) → consider urgent direct-access CT within 2 weeks; ultrasound if CT unavailable (NG12).
- Jaundice aged ≥40 → Suspected cancer pathway (NG12).
- Infection or acute illness: stress hyperglycaemia → treat the illness; reassess glucose once recovered.
- With low phosphate, potassium or urate, acidosis, proteinuria or low eGFR (Fanconi) → review drugs → Nephrology
- Pancreatic, Cushingoid, acromegalic or haemochromatosis clues → secondary diabetes work-up.
3Assess — the blood test splits it
☐ Osmotic symptoms, speed, weight ☐ Drugs: SGLT2 inhibitor; steroids, thiazides, antipsychotics, tacrolimus, ciclosporin ☐ Pregnancy ☐ Plasma glucose and/or HbA1c
Diabetes: HbA1c ≥48 mmol/mol, fasting ≥7.0 or random ≥11.1 mmol/L with symptoms; repeat if asymptomatic. Use plasma glucose, not HbA1c, in children, suspected type 1, short symptoms, pregnancy, acute illness, recent steroids or altered red cell turnover.
4Classify — raised or normal glucose?
- Type 2 — older or overweight, risk factors, gradual, often asymptomatic → NG28 / local.
- Type 1 / latent autoimmune — young or lean, rapid symptoms, weight loss, ketosis → same-day specialist.
- Non-diabetic hyperglycaemia — HbA1c 42–47 mmol/mol → lifestyle support and periodic retesting.
- Gestational — OGTT fasting ≥5.6 or 2-hour ≥7.8 mmol/L (NG3) → antenatal pathway.
- Renal glycosuria — normal glucose, HbA1c and renal function, no tubular losses → benign. SGLT2 inhibitor — expected effect.
- Uncertain — atypical type, possible monogenic (onset <25, several generations) or secondary cause → endocrinology; never trial oral agents while type 1 is possible.
5Treat today — the cause, never the urine
- Suspected type 1 or ketosis: insulin is started under specialist care; do not delay it.
- Confirmed type 2: education, diet, activity; NG28 (February 2026): MR metformin then an SGLT2 inhibitor for most (metformin alone considered in frailty), per local guidance formulary. Doses: NICE/SPC, BNF, local formulary.
- On an SGLT2 inhibitor: genital hygiene, sick-day rules (withhold in acute illness, dehydration, fasting, surgery), ketone awareness.
- Steroid-induced: capillary glucose timed to the dose; HbA1c will miss it. Renal glycosuria: reassure, code the diagnosis, discharge.
6Refer routinely
- Atypical or uncertain type, suspected monogenic or secondary diabetes → endocrinology.
- Tubular disorder, falling eGFR or proteinuria → nephrology.
- Confirmed gestational diabetes → joint antenatal and diabetes clinic. Non-diabetic hyperglycaemia → NHS Diabetes Prevention Programme.
- New diabetes: eGFR, ACR, lipids, BP, BMI, feet, retinal screening.
7Never reassure by
- A negative dipstick — it does not exclude diabetes.
- A normal HbA1c in a child, suspected type 1, short symptoms, pregnancy or recent steroids.
- A near-normal glucose in an unwell patient on an SGLT2 inhibitor.
- An older or overweight adult — type 1 occurs at any age or BMI.
- Weight loss called “good glycaemic control” in new diabetes at 60+.
- Urine ketones when blood ketones are available.
8Safety-net — say it, then document it
999 “If you are being sick, get tummy pain, breathe fast or deeply, or feel drowsy or confused, call 999 or go to A&E — don't drive yourself.” Same-day “If you get much thirstier or keep losing weight before the result is back, contact us the same day.”
Renal glycosuria: reassure and record the diagnosis so future dipsticks are not misread. Driving: whether to tell the DVLA depends on the treatment and licence group.
✓Safe to leave primary care only if — all five, documented
No block 0–2 row applies; ketones checked if symptomatic
Drugs (SGLT2 inhibitor, steroids) and pregnancy reviewed
Laboratory glucose or valid HbA1c done
Conclusion recorded: diabetes type, renal glycosuria or drug effect
Safety-net given; repeat test or recall booked
Summary of the full Reasoning GP glycosuria algorithm, which holds the detail, differential and evidence. Sources: NICE NG28 (updated February 2026), NG17, NG18, NG3, NG12 (updated April 2026), PH38; JBDS-IP DKA (2023) and HHS (2022); MHRA; local. Clinical reference — follow local pathways and check doses: NICE/SPC, BNF.