Changes in reporting and diagnostic use of HbA1c

news item on the changes made to the reporting units for HbA1c in Australia and replaceing glucose with HbA1c for diagnosis of diabetes

A Position Statement issued jointly by the Australasian Association of Clinical Biochemists (AACB), the Royal College of Pathologists of Australasia (RCPA), Australian Diabetes Society (ADS) and Australian Diabetes Educators Association (ADEA) has recommended changes in HbA1c reporting units. The change is from the current DCCT/NGSP ‘%’ unit to the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) unit ‘mmol/mol’.

To facilitate a smooth transition to this new IFCC unit and enable time for promotion and education of the new unit, the AACB recommends a period of dual reporting of both NGSP % and IFCC mmol/mol units after which only the IFCC unit will be reported.

Targets and Reference Ranges in new units

  • The old DCCT/NGSP target of 7.0%, or now commonly 6.5%, will in future be 53 and 48 mmol/mol respectively.
  • The now no-longer recommended ‘Change of Therapy’ level of 8.0% will be 64 mmol/mol.
  • The old DCCT/NGSP reference range of 4.0 – 6.0% HbA1c will be reported as 20 – 42 mmol/mol HbA1c.

Diagnosing diabetes using HbA1c

In addition to the change in reporting units, authorities in the field are saying that Australian doctors will soon be diagnosing diabetes using HbA1c despite some concerns that the test is not as accurate as current glucose testing.

The international community is moving toward the use of HbA1c as the diagnostic test of choice and experts in the field such as Associate Professor Jonathan Shaw, deputy director of the Baker IDI Heart and Diabetes Institute in Melbourne and Professor Stephen Colagiuri, a member of a WHO committee assessing the use of HbA1c for diabetes diagnosis expect the HbA1c test to be formally introduced into Australian practice within the next year.

Some studies have suggested the move to HbA1c would appear to reduce substantially the prevalence of diabetes however, Professors Shaw and Colagiuri both believed that while diabetes prevalence might technically drop on a population-wide level, this would be balanced out by the increased ease of case detection and that rates in clinical practice would remain similar.



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