HbA1c

What is HbA1c?

Haemoglobin (Hb) circulates within the red blood cells and is constantly reacting with other compounds surrounding it in the blood. A variety of different molecules in blood can attach themselves to haemoglobin (permanently or temporarily) and one such compound is glucose.

As the Hb in our blood is exposed to increasing levels of glucose, so more of this glucose attaches to the circulating Hb to form HbA1c. HbA1c is a form of glycated haemoglobin.

The addition of glucose to haemoglobin in this way is off-set by the continual production of new Hb within the body that does not have glucose attached to it, and the breakdown of old red blood cells that have formed HbA1c, which are then removed from the blood circulation.

This is a complex dynamic process that results in higher HbA1c levels in patients with diabetes than in non-diabetic individuals. Measurement of HbA1c levels in diabetic patients is a well evidenced method of assessing glycaemic control over the previous 4-8 weeks and is heavily relied upon by both clinicians and patients.

HbA1c and Diagnosis

In 2011 The World Health Organisation approved use of HbA1c for diagnosis of diabetes1 if certain quality criteria for the analysis were met, including stringent quality assurance tests.

An Expert Group within the UK have approved the use of POCT HbA1c devices for diagnosis of diabetes, stating:

"Point of care HbA1c should not be used for diagnosis unless the healthcare staff have been appropriately trained and the HbA1c method used can demonstrate an internal quality control and external quality assessment performance that matches that of a laboratory method. Confirm a point of care diabetes diagnosis with laboratory venous HbA1c."  2

1 World Health Organization. (2011) Use of Glycated Haemoglobin (HbA1c) in the Diagnosis of Diabetes Mellitus. Abbreviated Report of a WHO Consultation. WHO, Geneva. Available at: http://bit.ly/seLcYT
2 Diabetes & Primary Care Vol 13 No 6 2011

HbA1c Quality Assurance

Although HbA1c has traditionally been measured within the central hospital laboratory, there have been devices available for measuring it in capillary finger prick blood samples at the point of patient care for over 20 years.

How can you be confident that the HbA1c results from your point of care testing (POCT) device are as reliable as those from the laboratory? Do you have any evidence?

Can we be sure that our POCT analysers and reagents for HbA1c continue to give the right results?

Measurement of HbA1c levels in diabetic patients is a well established method of assessing glycaemic control and is relied upon by both clinicians and patients as an important tool in managing the disease.

Are you using POCT HbA1c for diagnosis of diabetes? If so, you are responsible for life changing results and the requirement for top quality results is paramount.

There are 3 key steps that you can take to assure the quality of your HbA1c results:

Know what you are doing
  • Healthcare Professionals should always be trained by the HbA1c device manufacturer or by local laboratory staff and be certified as competent to perform the test.
  • Make sure you have read and understood the instructions supplied with your HbA1c testing device.
  • Pay attention to any limitations that may be listed – this means that the device may not be suitable for patients with certain conditions or if taking particular medication.
  • Make sure your consumables and QC solution have not passed their opened or unopened expiry dates.
  • Are you storing your test cartridges and QC solution at the right temperature?
  • Is your device correctly calibrated?
Use Quality Control
  • The manufacturer of your HbA1c device will provide you with Quality Control (QC) material which must be stored, prepared and tested according to the manufacturer's instructions.
  • The HbA1c result you obtain for this QC material should fall within the range of results quoted by the manufacturer.
  • When you run a quality control test you will know straight away whether the result is acceptable or not. Achieving good QC results will give you immediate information and the confidence to continue to use your device and act upon the results.
  • If your QC results are not within range, follow the manufacturer's instructions to troubleshoot the problem and do not use the device for testing patient samples until the issue is resolved.
  • In 2011 The World Health Organisation1 approved use of HbA1c for diagnosis of diabetes if certain quality criteria for the analysis were met, including stringent quality assurance tests.
  • An Expert Group within the UK have approved the use of POCT HbA1c devices for diagnosis of diabetes, stating: "Point of care HbA1c should not be used for diagnosis unless the healthcare staff have been appropriately trained and the HbA1c method used can demonstrate an internal quality control and external quality assessment performance that matches that of a laboratory method. Confirm a point of care diabetes diagnosis with laboratory venous HbA1c."  2

1 World Health Organization. (2011) Use of Glycated Haemoglobin (HbA1c) in the Diagnosis of Diabetes Mellitus. Abbreviated Report of a WHO Consultation. WHO, Geneva. Available at: http://bit.ly/seLcYT
2 Diabetes & Primary Care Vol 13 No 6 2011

Use Qpoint External Quality Assessment
  • Participation in an External Quality Assessment Scheme or "EQAS" such as Qpoint for your POCT HbA1c device is recommended by the Medicines & Healthcare Regulatory Agency (MHRA) in the UK3.
  • If you are using HbA1c results for diagnosis of diabetes, participation and satisfactory performance in an EQAS is essential 1,2.
  • When you enrol and participate in Qpoint you are sent a regular monthly blood sample to test on your HbA1c device but you do not know what the correct result should be.
  • You submit the result you obtain back to the EQAS organisers, who compare your result to the results that other users of the same device have submitted for the same test sample.
  • There may be 100s or 1000s of users of the same type of device registered with the scheme from around the UK, or internationally, that your result will be compared to.
  • The following month, when you receive your next test blood sample, you will also receive a report that tells you how well your previous result agreed with all other users of the same device registered with our scheme.
  • The Qpoint report is easy to understand and gives advice on any action that you may need to take to improve the quality of your results.
  • If your EQA test results are in good agreement with other users of the same device you will have reassurance that your device and consumables are working as they should under your own local conditions and that your testing procedures continue to meet the manufacturer's specification.
  • The Qpoint organisers work totally independently of the POCT device manufacturers but when problems are identified with any particular instrument the manufacturer is advised and encouraged to address the issue.
  • Any serious problems identified are reported to the MHRA.

1 World Health Organization. (2011) Use of Glycated Haemoglobin (HbA1c) in the Diagnosis of Diabetes Mellitus. Abbreviated Report of a WHO Consultation. WHO, Geneva. Available at: http://bit.ly/seLcYT
2 Diabetes & Primary Care Vol 13 No 6 2011
3 MHRA Device Bulletin: Management and Use of IVD Point of Care Test Devices. DB2010(02) February 2010

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