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

Why is Haemoglobin A1c (Glycated Haemoglobin) measured?

HbA1c is the standard long-term glycaemic status marker for diabetes screening, diagnosis, and treatment monitoring. In female functional health panels, HbA1c serves as the integrated carbohydrate metabolism marker — identifying prediabetes well before fasting glucose becomes overtly abnormal, monitoring glycaemic trend in patients on dietary intervention, and providing the glycaemic context for interpreting sex hormone patterns, as insulin resistance drives PCOS-associated androgen excess, SHBG suppression, and ovulatory dysfunction.

Reference ranges

Standard reference

<5.7% (<39 mmol/mol) normal; 5.7–6.4% (39–46 mmol/mol) prediabetes; ≥6.5% (≥48 mmol/mol) diabetes # REVIEWER FLAG: Diagnostic thresholds follow ADA criteria; reviewer to confirm the platform's preferred diagnostic framing and LabCorp assay alignment (NGSP/IFCC) before publication.

Functional medicine optimal

<5.4% (<36 mmol/mol) (functional medicine optimal for minimising metabolic and cardiovascular risk below the prediabetes threshold). # REVIEWER FLAG: <5.4% optimal is used in integrative practice but is not a formal clinical guideline threshold — 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.