HbA1c methods and Hemoglobin Variants (HbS, HbC, HbE and HbD traits)
Updated 2/2010

HbA1c, also called A1C, is a measure of the amount of glucose attached to hemoglobin (Hb) in red blood cells. The higher the glucose levels over the previous 2-3 months, the higher the A1C. The A1C test is used to monitor the glucose levels of patients who have been diagnosed with diabetes.

In people who have hemoglobin variants such as HbS (sickle cell trait), some A1C tests give falsely high or low readings that can lead to the over-treatment or under-treatment of diabetes.  Laboratories use many different methods for measuring A1C, but some of these methods can give inaccurate results when the patient has a hemoglobin variant such as sickle cell trait. Doctors or patients interested in getting information about the accuracy of a particular A1C method for patients with hemoglobin variants should first find out which method your laboratory is using.

The following table lists the 21 methods most often used to measure A1C and whether the method is affected by either HbS or HbC or HbE or HbD trait. Methods are listed in alphabetical order by manufacturer. If your diabetes patient has a hemoglobin variant, your lab should use one of the methods that does not show interference from the variant, thus producing an accurate A1C result.

Interference from

Method

HbAS

HbAC

HbAE

HbAD

Abbott Architect/Aeroset

Yes

Yes

-

-

Axis-Shield Afinion

No

No

No

No

Bayer (Metrika) A1cNOW

Yes

Yes

No

No

Beckman Synchron System

No

No

No

No

Bio-Rad D-10

No

No

No

No

Bio-Rad Variant A1c

No

No

No

Yes

Bio-Rad Variant II A1c

No

No

No

No

Bio-Rad Variant II Turbo A1c

No

No

Yes

Yes

Dade Dimension

No

No

No

No

Olympus AU system

Yes

Yes

No

No

Ortho-Clinical Vitros

No

No

No

No

Primus HPLC (affinity)

No

No

No

No

Roche Cobas Integra Gen.2

No

No

No

No

Roche/Hitachi (Tina Quant II)

No

No

No

No

Siemens (Bayer) Advia HbA1c # (original version)

Yes

Yes

-

-

Siemens (Bayer) Advia A1c (new version)

No

No

-

-

Siemens (Bayer) DCA 2000

No

No

-

-

Tosoh A1c 2.2 Plus

No

No

Yes

No

Tosoh G7

No

No

Yes

No

Tosoh G8

No

No

-

-

# This method is being replaced by the newer A1c version

More comprehensive information regarding HbA1c assay interferences

More (from the NIDDK web site):
Sickle Cell Trait and Other Hemoglobinopathies and Diabetes: Important Information for Physicians
For People of African, Mediterranean, or Southeast Asian Heritage: Important Information about Diabetes Blood Tests