Helena Biosciences’ Haemoglobin A1c test

Helena Biosciences’ Haemoglobin A1c test

A quick, reliable and cost-effective method for diagnosing and monitoring diabetes mellitus. 

Diabetes mellitus: A global issue

Diabetes mellitus is becoming increasingly common globally. In 2014, the number of adults living with diabetes was estimated at around 422 million, almost a 4-fold increase since 1980, where it was 108 million1 (Fig. 1). Type 2 diabetes accounts for 85-90% of diabetes cases. The healthcare cost of diabetes to the NHS in the UK alone has been estimated to be £23.7bn and it is expected that this figure will rise to £39.8bn by 2035-362. It is therefore of pivotal importance that methods are put in place for diabetes prevention and early diagnosis to reduce the healthcare, economic and social burdens of the disease, as early stages of type 2 diabetes are often asymptomatic and can remain so for several years3.

What is diabetes mellitus?

Diabetes mellitus is a metabolic disorder where the hormone ‘insulin’ does not efficiently promote the storage of glucose. This leads to hyperglycaemia and changes in the metabolism of lipids, proteins and carbohydrates, which can result in serious problems such as blindness, kidney failure and limb amputations. There are two types of diabetes:

  • Type 1 diabetes: caused by the destruction of the beta cells responsible for producing insulin and is mainly diagnosed in children and adolescents.
  • Type 2 diabetes: tends to be due to either low levels of insulin being secreted, or the insulin not being correctly recognised by its receptors, and is more common in adults3.

What tests are used to diagnose and monitor diabetes?

There are currently three main screening tests used to detect and monitor diabetes: Random or Fasting Plasma Glucose (FPG), Oral Glucose Tolerance Test (OGTT) and HbA1c4.

Studies of FPG have shown it to have lower sensitivity than expected, as almost one-third of people with the disorder were undetected5. On top of this, the FPG test has to be repeated at least twice in order to confirm the diagnosis4. OGTT is a more reliable method, but it is a costly and time-consuming procedure.

With both FPG and OGTT, patients have to fast for at least 8 hours before they can be tested. A patient’s failure to fully comply with guidelines for these tests reduces their accuracy4.

HbA1c now a WHO-recommended test

HbA1c testing was recommended by the World Health Organization (WHO) in 2011, as a tool for diabetes mellitus diagnosis6. It uses haemoglobin (Hb) A1c as a marker for diabetes. HbA1c is a glycated component in the blood, which results from the post-translational modification of a fraction of haemoglobin A, by the non-enzymatic reaction of its β-chain N-terminal valine with a glucose molecule. When there are higher, prolonged concentrations of glucose in the blood, the levels of HbA1c are greater also7.

The big benefit of HbA1c testing is that HbA1c levels correlate with an individual’s average blood glucose levels over 2-3 months and so fasting is not required prior to the test. This makes it a quicker, more convenient method4.

Techniques used for HbA1c testing

HbA1c testing is performed using several different techniques, but the most common commercial assays are:

  • Ion exchange HPLC: haemoglobin species are put through a negatively charged column and separated according to their charge. This method is susceptible to Hb variant interference though and has to be performed on a dedicated HPLC instrument also, which can be costly.
  • Immunoassays: use antibodies that selectively bind to the glycated N-terminal sequence of HbA1c. This method is currently the most commonly used but again is susceptible to Hb variant interference.
  • Capillary electrophoresis: the haemoglobin species are separated out in a capillary based on their charge and hydrodynamic size. This is the more recently optimised method for HbA1c testing.

Capillary Electrophoresis

Electrophoresis is a technique that separates sample components based on differences in their mass-to-charge ratio. The tertiary structure of a protein and its subsequent mass-to-charge ratio is dependent on the number and position of ionically active residues within its make-up.

Capillary Zone Electrophoresis occurs when high voltage is applied to an uncoated fused silica capillary tube filled with a uniform electrolyte solution. Separation of the charged analytes is due to differential migration in the electrical field. Positively charged ions are drawn through the capillary towards the cathode, with the smallest most positively charged ions eluting first.

Helena Biosciences’ Haemoglobin A1c test on the V8 NEXUS

Helena Biosciences have recently released their V8 HbA1c Kit, developed for use on their V8 NEXUS third-generation capillary electrophoresis analyser.

It is a fully automated capillary electrophoresis method which when used in conjunction with the V8 HbA1c Calibrator Kit, is calibrated to the standardised material supplied by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) for the diagnosis and monitoring of type 2 diabetes. The test measures HbA1c in fresh whole blood, providing results in all of the globally accepted measurement units (HbA1c relative percentage, HbA1c mmol/mol and estimated Average Glucose mmol/L).

Samples can be automatically lysed inside the V8 system. The prelysis technique resolves the issue of the capillaries blocking, which can happen with cap-piercing, when the small rubber granules from the primary tube cap, collect together and form a blockage. Prelysis ensures a truly smooth workflow, providing the preparation of 100 samples at one time, whilst minimising repeated analysis.

Minimal costs, high throughput and new Platinum 5 Touch software

The V8 NEXUS can run 32 tests/hour on HbA1c and is ideal for customers with a throughput between 6,000 and 50,000 tests per year. It can connect to the Inpeco FlexLab, Abbott Accelerator and Siemens Aptio automated laboratory track systems and all samples and buffers on-board the V8 are bar-coded for full audit traceability.

The system provides easily interpretable traces with the new Platinum 5 software’s touch screen interface. It has a range of sophisticated viewing and editing capabilities and HbA1c peaks are highlighted, with traffic-light colour coding for simple interpretation (Fig. 2, 3 and 4). The software automatically controls the analyser and makes ordering your HbA1c tests simpler than ever.

With the V8 HbA1c test, common Hb variants (such as HbS, HbC, HbD and HbE) do not interfere with the identification of the HbA1c peak as they migrate to the right of the HbA1c peak rather than comigrating with it. 

Conclusion

Minimal instrument costs, a seamless workflow with prelysis, and touchscreen interpretation, have made the new Helena Biosciences’ V8 HbA1c Kit a quick, reliable and cost-effective solution that is providing laboratories worldwide with higher throughput and greater confidence in results. With HbA1c testing now being a WHO-recommended method and a desirable alternative to FPG and OGTT, there is no better time to be using capillary electrophoresis HbA1c testing for the diagnosis and monitoring of diabetes.

References

  1. World Health Organization, Global report on diabetes, WHO/NMH/NVI/16.3, ed. Geneva, World Health Organization, 2016. 

  2. Diabetes UK. Diabetes: Facts and Stats. https://www.diabetes.org.uk/ Documents/About%20Us/Statistics/Diabetes-key-stats-guidelines- April2014.pdf. [Accessed 6th October 2017].
  3. World Health Organization, Definition, diagnosis and classification of diabetes mellitus and its complications. Part 1: diagnosis and classification of diabetes mellitus. WHO/NCD/NCS/99.2, ed. Geneva, World Health Organization, 1999. 

  4. Bennett CM, Guo M, Dharmage SC, HbA1c as a screening tool for detection of Type 2 diabetes: a systematic review. Diabetic Medicine. 2007; 24: 333-343. 

  5. Barr RG, Nathan DM, Meigs JB, Singer DE. Tests of glycemia for the diagnosis of type 2 diabetes mellitus. Annal Intern Med 2002; 137: 263–272.
  6. World Health Organization, Use of glycated haemoglobin (HbA1c) in the diagnosis of diabetes mellitus. WHO/NMH/CHP/CPM/11.1, ed. Geneva, World Health Organization, 2011. 

  7. Rhea JM, Molinaro R, Pathology Consultation on HbA1c Methods and Interferences. Am. J. Clin. Path. 2014;141: 5–16.

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11 October 2017 8:45

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