HbA1c

The HbA1c Test HbA1c reflects average plasma glucose over a period of time Can be used as a diagnostic test Provided the assay is standardised and stringent QA is in place No interfering health conditions It can be performed at any time of the day and does not require any special preparation such as fasting It is the preferred test for assessing glycaemic control in people with diabetes

Clinical Significance of HbA1c The higher the HbA1c The greater the risk of developing diabetes-related complications For every 1% decrease in HbA1c There is a 21% reduction in the risk of diabetes-related deaths Reduction in the risks of developing microvascular complications Prevalence of kidney disease is also reduced by 25%. Important to monitor and maintain a low HbA1c level This level can be lowered with a good diet, exercise and medication.

The New HbA1c Recording Units Up until now HbA1c was reported as a % of the total HbA which is glycated Different methods gave different results for HbA1c All assays must now be calibrated against the international reference method Results now reported as a ratio: mmol of glycated HbA: mol of non-glycated HbA [mmol/mol]

Measuremmol/mol% Non-diabetics mmol/mol4- 5.9% Diabetics48 mmol/mol6.5% Hypoglycemiac Prone Diabetics 59 mmol/mol7.5% Figure 1. Diagram of HbA1c targets (

Charge Ion-exchangehighpressure liquidchromatography Ion-exchange high pressure liquid chromatography Structure Boronateaffinitychromatograph Boronate affinity chromatograph Separates glycated and non- glycated compounds Immunoassays Immunoassays Employ the use of antibodies Interferences are rare Difficult to detect

HbA1c Controls Different factors can affect the performance of the assay. pH, temperature, dilution To assure the accuracy and precision, controls are required Ensure reliable results. Only when controls are used routinely and the values obtained are within acceptable ranges can accurate results for patient samples be assured.

References Gough, S., Manley, S. and Stratton, I. (2010). HbA1c in Diabetes. New York, NY: John Wiley & Sons. Vlad, S. and Ciupa, R. (2011). International Conference on Advancements of Medicine and Health Care Through Technology, 29 August - 2nd September 2011, Cluj-Napoca, Romania. [Berlin]: Springer. Diabetes.co.uk, (2012). What is HbA1c? - Definition, Units, Conversion, Testing & Control. [online] World Health Organisation, (2011). Use of Glycated Haemoglobin (HbA1c) in the Diagnosis of Diabetes Mellitus. [online] Mayomedicallaboratories.com, (2009). Hot Topic - Hemoglobin A1c & the Estimated Average Glucose - Mayo Medical Laboratories. [online]