Changing Values

• When does 6.5 = 48?

Is this a well controlled diabetic?

Date HbA1c mmol/mol

23/04/2011 45

01/11/2010 48

12/01/2010 55

15/11/2009 65

01/09/2009 70

03/07/2009 86

03/05/2005 75

Before 2009

• HbA1C results would have appeared as:

Haemoglobin A1c 7.0% total Hb (3.6-6.8)

The HbA1c is expressed as a percentage of the Total Haemoblobin relative to a calibrator aligned to the DCCT method

After June 2009

• HbA1c results have appeared as:

Haemoglobin A1c 7.0% total Hb (3.6-6.8)

HbA1c (IFCC) 53 mmol/mol

The second result has been obtained using the IFCC reference standard

From June 2011

• HbA1c results will appear as:

HbA1c (IFCC) 53 mmol/mol (<48)

Relationship between old and new units

• IFCC-HbA1c (mmol/mol) = [DCCT-HbA1c (%) – 2.5] x 10.929

International Federation of Clinical Chemistry

Diabetes Control and Complications Trial

Following agreement between the various professions a series

of leaflets were produced outlining the changes.

Standardisation of HbA1c Assays.

HbA1c measured by ion-exchange chromatography as the glucose changes the charge on the haemoglobin molecule.

Originally calculated as a percentage of the HBA peak.

After the DCCT trial and the importance of meeting a set target was established a standardised approach was used to align methods to the DCCT method.

Not a true standard, so a reference standard was produced and a method assigned by isotope dilution mass spectrometry. Enables to report values in molar terms.

• www.diabetes.org.uk/Guide-to-diabetes/Monitoring/Blood_glucose/Glycated_haemoglobin_HbA1c_and_fructosamine/

• Calculator to convert from old to new units and links to leaflets one of which is for patients.

Diagnosis of Diabetes• Based exclusively on fasting glucose and

oral Glucose Tolerance Test.

• March 2011 WHO issued a report with the following recommendation

6.5% = 48 mmol/L

“Use of Glycated Haemoglobin

(HbA1c) in the Diagnosis of Diabetes

Mellitus

Abbreviated Report of a WHO Consultation

March 2011”

Available on the WHO Diabetes website

Answer

• When does 6.5 = 48?• When they refer to HbA1c measurements• An HbA1c of 6.5% = HbA1c of 48 mmol/mol.

Is this a well controlled diabetic?

Date HbA1c mmol/mol

HbA1C

%

23/04/2011 45 6.6

01/11/2010 48 6.9

12/01/2010 55 7.5

15/11/2009 65 8.4

01/09/2009 70 8.9

03/07/2009 86 10.4

03/05/2005 75 9.4