HbA1c (IFCC) measures glycated haemoglobin and reports the result in IFCC units (millimoles per mole, mmol/mol). It reflects average blood glucose over the preceding 2–3 months — the lifespan of a red blood cell — providing a stable, long-term snapshot of glycaemic control that is not affected by short-term dietary changes or the time of day.

The IFCC reporting standard is used in Australia, the UK, and most of Europe. An HbA1c below 42 mmol/mol is considered normal; 42–47 mmol/mol indicates pre-diabetes; 48 mmol/mol or above confirms diabetes. HbA1c is also used to monitor how well diabetes is being managed over time.