Diabetes mellitus is a common group of metabolic disorders with a global prevalence of around 8.5%, or approximately 422 million people, according to the World Health Organization (WHO) in 2014 [1].
Diabetes is characterized by frequent periods of uncontrolled hyperglycemia and is divided into two main types: type 1 and type 2. Type 1 diabetes is characterized by a deficiency of insulin production from the pancreas, leading to uncontrolled blood glucose levels. Type 2 diabetes, the most common form, involves either the pancreas not producing enough insulin or the body’s cells becoming resistant to the action of insulin.
What are the Diabetes Testing Methods?
The gold-standard diagnostic method for diabetes has previously been measuring either fasting blood glucose (FBG) or two-hour plasma glucose via an oral glucose tolerance test (OGTT) [2].
The diagnostic criteria for a patient to be considered diabetic using FBG or OGTT are:
- FBG ≥7.0 mmol/l, or
- Two-hour plasma blood glucose concentration must be ≥11.1 mmol/l two hours following administration of a 75g anhydrous glucose via an OGTT
Although both testing methods provide good accuracy, they present their limitations. Both tests rely on suitable application within specific periods and patient compliance.
For example, pre-test preparation for testing two-hour plasma blood glucose concentration includes providing patients with a strict diet three days before testing and overnight fasting.
The FBG test requires at least 8 hours of fasting before completion. Traditional diagnostic methods can seem daunting and time-consuming, making patient compliance difficult to achieve.
The requirement to fast with traditional glucose testing methods can be a potentially problematic compliance standard for some, especially those struggling with glycemic control. Some patients may consume food or beverages (aside from water) during fasting, believing this small action would not affect the testing results. Still, this would usually mean the test would have to be repeated.
The OGTT relies on the patient remembering to adhere to the test conditions during the two hours. There is a chance that the patient will fail to return to the testing location in the appropriate time frame to obtain accurate results.
What is HbA1c?
Hemoglobin, a protein in red blood cells, bonds with oxygen to transport it around the body. However, it can also bond with glucose in the bloodstream, resulting in glycated hemoglobin or HbA1c.
Glycation is irreversible, so HbA1c remains in this state in the red blood cell for around eight to twelve weeks, which is the lifespan of the red blood cell. The more HbA1c found within the blood, the greater the chance the patient has diabetes or is at risk for developing the disorder.
Diabetes onset, particularly type 2 diabetes, tends to be slow, with small and gradual increases in blood glucose levels over time [3]. Early and accurate diagnostic techniques are essential for improving patient care.
Glycated hemoglobin is a diagnostic approach that provides insight into chronic hyperglycemia rather than testing glucose in a fasting state or over two hours.
Using this diagnostic tool, the glycemic index is tested for the 120-day lifespan of the red blood cell [4]. The HbA1c method, therefore, may stratify risk and provide a firm diabetes diagnosis.
In 2009, the International Expert Committee recommended introducing the diagnostic criteria of HbA1c at a threshold of ≥48 mmol/mol (≥6.5%) [5]. The WHO and the American Diabetes Association adopted the recommendation of HbA1c for diabetes testing, stating that an HbA1c of 6.5% or more is the cut-off point for a diabetes diagnosis [6].
Additionally, the WHO approved using point-of-care testing (POCT) devices for HbA1c diagnostic techniques that are traceable to the International Federation of Clinical Chemistry (IFCC) reference method. For example, the Quo-Test analyzer by EKF Diagnostics is a POCT analyzer that directly measures HbA1c in minutes using a 4 μl blood sample from a simple finger prick.
Before POCT devices, HbA1c tests provided little to no time or value advantage over traditional diagnostic strategies. However, using systems like EKF Diagnostics’ Quo-Lab A1c Analyzer, researchers can quickly gain insight into a patient’s risk for diabetes and pre-diabetes. With a diagnosis in minutes, earlier treatment can occur. Early treatment is ideal as it may reduce long-term deleterious effects, including worsening glycemic function and blood vessel damage [7].
Given the minimal preparation associated with the test, using HbA1c as a diagnostic marker for diabetes may promote a higher rate of patient compliance. Only one blood sample is used, providing accurate initial results without necessitating repeat testing.
Considering that a large proportion of the population with diabetes or prediabetes goes undiagnosed, HbA1c testing may reduce global morbidity associated with the disorder [10].
However, there are a few patient groups who are not desirable candidates for HbA1c testing, including pregnant women, children, and patients with a history of acute pancreatic damage or pancreatic surgery [11].
References:
- [1] Global report on diabetes. World Health Organization. http://www.who.int/diabetes/global-report/en/.
- [2] American Diabetes Association. Diagnosis and classification of diabetes mellitus. Diabetes Care. 2010;33 Suppl 1:S62-S69.
- [3] Florkowski C. HbA1c as a Diagnostic Test for Diabetes Mellitus – Reviewing the Evidence. Clin Biochem Rev. 2013;34(2):75-83.
- [4] Sacks DB. Correlation between hemoglobin A1c (HbA1c) and average blood glucose: can HbA1c be reported as estimated blood glucose concentration? J Diabetes Sci Technol. 2007;1(6):801-803.
- [5] International Expert Committee. International Expert Committee report on the role of the A1C assay in the diagnosis of diabetes. Diabetes Care. 2009;32(7):1327-1334.
- [6] Use of Glycated Haemoglobin (HbA1c) in the Diagnosis of Diabetes Mellitus. World Health Organization. http://www.who.int/cardiovascular_diseases/report-hba1c_2011_edited.pdf.
- [7] Romanelli RJ, Chung S, Pu J, et al. Comparative effectiveness of early versus delayed metformin in the treatment of type 2 diabetes. Diabetes Res Clin Pract. 2015;108(1):170-178.
- [8] Crawford SO, Hoogeveen RC, Brancati FL, et al. Association of blood lactate with type 2 diabetes: the Atherosclerosis Risk in Communities Carotid MRI Study. Int J Epidemiol. 2010;39(6):1647-1655.
- [9] Wu Y, Dong Y, Atefi M, et al. Lactate, a Neglected Factor for Diabetes and Cancer Interaction. Mediators Inflamm. 2016;2016:6456018.
- [10] Dunstan DW, Zimmet PZ, Welborn TA, et al. The rising prevalence of diabetes and impaired glucose tolerance: the Australian Diabetes, Obesity and Lifestyle Study. Diabetes Care. 2002;25(5):829-834.
- [11] John WG. Use of HbA1c in the diagnosis of diabetes mellitus in the UK. The implementation of World Health Organization guidance 2011. Diabet Med. 2012;29(11):1350-1357.
