A 7-year-old boy presents to the children’s emergency department with fever and cough. He’s alert, well-hydrated, and playful in the waiting room. To rule out UTI, a urine dipstick is performed: no nitrites, no leukocytes… but 3+ glucose.
A capillary blood glucose is 5.8 mmol/L. Ketones are negative.
Is this just a viral illness with an odd finding, or the start of something much more significant?
Why glycosuria matters
Glycosuria is one of those small findings that can cause big anxiety. In children, it’s often incidental, but it may also be the earliest clue to a life-changing diagnosis. Our challenge, often, is to decide: is this incidental, or do I need to act right now?
The physiology refresher
Normally, the proximal tubule reabsorbs almost all of the filtered glucose.
When plasma glucose exceeds the renal threshold (≈ 180 mg/dL or 10 mmol/L in most children), glucose spills into urine.
Alternatively, tubular reabsorption may be impaired, even with normal plasma glucose.
Differential diagnosis
Hyperglycaemic causes
- Type 1 diabetes mellitus – the one we don’t want to miss.
- Type 2 diabetes – increasingly recognised in obese adolescents.
- Stress hyperglycaemia – acute illness, trauma, seizures.
- Steroid or catecholamine excess.
Normoglycaemic causes
- Familial renal glycosuria (benign, due to SGLT2 mutations).
- Fanconi syndrome (proximal tubulopathy with phosphate, bicarbonate, amino acid wasting).
- Transient glycosuria during illness or after carbohydrate load.
Artefact
- Contaminated sample (wet wipes, sugary hands).
- Old or mishandled dipsticks.
Does the “grade” of glycosuria matter?
Urine dipsticks report glucose semi-quantitatively, from trace/1+ up to 4+. The temptation is to assume that higher grades automatically mean more serious disease, but the evidence is more nuanced:
- Magnitude reflects urine concentration as well as glycaemia. A well-hydrated child may only show 1+, whereas the same blood glucose in a dehydrated child could give 3+ or 4+.7
- Threshold effect: Any glycosuria ≥1+ is abnormal in children and should trigger a blood glucose check.
- Predictive value: Higher grades (3+–4+) are more likely to correlate with hyperglycaemia/diabetes, but lower grades can still represent early disease, especially if repeated.
- Renal glycosuria: May produce persistent glycosuria across the whole range (from trace to 4+) despite consistently normal blood glucose.
Practical approach
1. Always check blood glucose
A dipstick alone doesn’t tell you everything about systemic glycaemia. A blood glucose test is more helpful.
- ≥11.1 mmol/L (random) + symptoms = diabetes until proven otherwise8. Investigate accordingly.
- Borderline high → repeat, may consider HbA1c, ketones, and red flags.
- Normal → pause, think wider.
2. Assess for ketones and red flags
- Symptoms: vomiting, abdominal pain, polyuria, polydipsia, Kussmaul breathing, weight loss, nocturia.
- If present, think DKA and act fast.
3. Think beyond the obvious
- Persistently normal glucose + glycosuria: renal causes should be on your radar.
- Intercurrent illness with isolated glycosuria: repeat when well; many cases will normalise.
- Co-existent proteinuria, poor growth, rickets: consider Fanconi syndrome or another tubulopathy.
4. Plan for follow-up
- If the child is well, glucose is normal, and ketones are absent → repeat urine after recovery
- If glycosuria persists, check renal function, electrolytes, HbA1c, and discuss with nephrology.
- Consider discussion with the GP/paediatric team for ongoing surveillance.
Our 7-year-old was well, normoglycaemic, and ketone-negative. His glycosuria resolved when repeated two weeks later. Parents were reassured but advised on red flags for diabetes. No further investigations were required.
Had the same child returned with vomiting, weight loss, or nocturia, the picture would have looked very different.
The key is to diagnose diabetes early!
What would you do?
A 12-year-old girl is brought in for abdominal pain. She’s overweight, with acanthosis nigricans. Her urine shows 1+ glucose and 2+ ketones. Her capillary blood glucose is 9.8 mmol/L. She’s otherwise well.
Would you:
- Discharge with reassurance and GP follow-up?
- Admit for serial monitoring?
- Refer urgently to the diabetes team?
Obesity + acanthosis raises suspicion for type 2 diabetes, but ketones and abdominal pain could herald type 1. This is the grey zone where clinical judgement counts – admission and senior discussion may be the safest option.
Take-home messages
Every glycosuria needs a blood glucose check.
Not all glycosuria equals diabetes – consider transient or renal causes.
Higher grades (3–4+) are more concerning, but even 1+ should not be dismissed.
Persistent glycosuria with normal glucose warrants nephrology or diabetes follow-up.
Safety net parents carefully – missed diabetes can present catastrophically.
References
Wolfsdorf JI. Pediatric Type 1 Diabetes Mellitus. Medscape. Updated December 16, 2024.
Dabelea D, et al. Incidence of diabetes in youth in the United States. JAMA. 2014;311(17):1778–1786.
Lee T, et al. Non-diabetic glycosuria as a diagnostic clue for acute illness. Pediatr Emerg Care. 2020;36(12):e688–e692.
Libman I, Haynes A, Lyons S, Pradeep P, Rwagasor E, Tung JY, Jefferies CA, Oram RA, Dabelea D, Craig ME. ISPAD Clinical Practice Consensus Guidelines 2022: Definition, epidemiology, and classification of diabetes in children and adolescents. Pediatr Diabetes. 2022 Dec;23(8):1160-1174. doi: 10.1111/pedi.13454. PMID: 36537527.
