What is this test?
HbA1c reflects the proportion of haemoglobin with glucose attached and estimates average glucose exposure over roughly the previous two to three months, with greater influence from recent weeks.
Why might it be ordered?
- To diagnose diabetes in an appropriate clinical setting.
- To monitor longer-term glucose control and treatment.
What sample is needed?
A blood sample is required. The laboratory chooses the correct tube and handles the sample for this test.
How should you prepare?
Fasting is not required. Tell your clinician about anaemia, recent bleeding or transfusion, pregnancy, kidney disease or a known haemoglobin variant because these can affect interpretation.
How should you understand the result?
Diagnostic thresholds and treatment targets are different. HbA1c may be misleading when red-cell lifespan or haemoglobin type is altered, so glucose-based testing may be needed.
Sources and editorial status
This patient-facing text is an editorial draft. It should be approved by a laboratory physician before official publication.