MLT GlobeHaemoglobin A1c (HbA1c)
Diabetes · also called Glycated haemoglobin, A1C
What it measures
HbA1c is the fraction of haemoglobin with glucose attached, reflecting average blood glucose over the past 2–3 months. It is used to diagnose diabetes and to monitor long-term glycaemic control.
Specimen and preparation
- Specimen: EDTA whole blood
- Tube: Lavender top
- Preparation: No fasting required.
Reference range
| Group | Range |
|---|---|
| Normal | <5.7 (<39) % (mmol/mol) |
| Prediabetes | 5.7–6.4 (39–46) % (mmol/mol) |
| Diabetes | ≥6.5 (≥48) % (mmol/mol) |
Reference ranges differ between laboratories, methods and populations. Always use the range printed on your own lab report.
Causes of high values
- Diabetes with poor control
- Iron deficiency anaemia
- Chronic kidney disease (carbamylation, some methods)
- Splenectomy
Causes of low values
- Haemolysis or blood loss
- Recent transfusion
- Pregnancy
- Haemoglobin variants (method-dependent)
- Erythropoietin or iron treatment
Method
HPLC (ion-exchange), immunoassay or enzymatic, NGSP/IFCC standardised
Good to know
Unreliable when red cell survival is altered; use glucose or fructosamine instead. Estimated average glucose (mg/dL) = 28.7 × A1c − 46.7.
Related tests
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