What does the Haemoglobin A1c (Glycated Haemoglobin) test measure?

Why is Haemoglobin A1c (Glycated Haemoglobin) measured?

HbA1c is the principal marker for diagnosing and monitoring type 2 diabetes and prediabetes and for assessing long-term glycaemic control, with treatment targets individualised to the patient. It does not require fasting and is less affected by day-to-day fluctuation than a single glucose measurement. Its reliability depends on a normal red-cell lifespan, so conditions altering erythrocyte turnover or haemoglobin structure can render it inaccurate, and alternative measures such as fructosamine may then be needed.

Reference ranges

Standard reference

Non-diabetic: <5.7% (<39 mmol/mol); prediabetes: 5.7–6.4% (39–47 mmol/mol); diabetes: ≥6.5% (≥48 mmol/mol) # REVIEWER FLAG: Diagnostic thresholds follow ADA/WHO criteria — reviewer to confirm the framing and units adopted by BiomarkersLabs.com.

Functional medicine optimal

<5.7% (non-diabetic range); individualised glycaemic targets apply in established diabetes # REVIEWER FLAG: Glycaemic targets in diabetes are individualised therapeutic goals, not a single optimal value — reviewer to confirm framing.

Units

%, mmol/mol

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.