Introduction diabetes is an autoimmune/idiopathic disorder where the


The world health organisation
(WHO) refers to the science of protecting and improving the health of families
and communities through advancement of analysis and treatment. Therefore, it is
apprehensive with international public health. (, 2017).

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Red blood cells also known as erythrocytes
are small biconcave disc shaped cells in the bloodstream that are coated with
oxygen carrying pigment called haemoglobin. (Bellad et al, 2016)
In hyperglycaemic state, the excess glucose in the bloodstream binds to haemoglobin
forming a molecule called ‘glycated haemoglobin’ (HbA1c). The greater the
amount of glucose present in the bloodstream, the more HbA1c will be present in
clinical serum of that patient. (Ang et al, 2015).

is diabetes?

Diabetes is a
chronic health disorder; it causes a state of hyperglycemia; high amount of
glucose in the circulation. Both type of diabetes cause a hyperglycemic state
leading to many complications (Mealey et al, 2007). Insulin is an anabolic hormone
produced by beta cells in the islets of Langerhans in the pancreas. (Fu et al, 2013). The hormone
works to regulate circulating glucose levels and keep them under reference
range. When we ingest a meal, carbohydrates from the diet are absorbed into the
circulation and a state of hyperglycemia develops. (Coll et al, 2007) The beta
cells in the pancreas then release insulin, which works to cause glucose absorption
into hepatic and muscle cells and reduce the circulating glucose levels. (Saltiel et al 2001). Insulin is commonly defined as a
key, which unlocks the doors to the cells, allowing glucose to pass in
(Whettem, 2014). Type 1 diabetes is an autoimmune/idiopathic disorder where the
beta cells attacks and destroy the insulin-producing cells, which then causes
absolute insulin deficiency. About 10 percent people with diabetes have type 1 (Hadjiyianni et al 2010). Mainly children and
young people develop type 1 diabetes however; there is a chance that elderly
people can develop it as well (Tuomi, 2005).Type 2 diabetes is when the body
does not make enough insulin, or when the body becomes resistant to insulin.
This results in a buildup of glucose in the blood. About 80-90%, people have with
diabetes have type 2. (Watkins et al, 2003).Type 2 diabetes is mainly common in
south Asian, African and Afro-Caribbean origin also; people who have family
history will also have a chance to develop type 2 diabetes. Type 2 diabetes can
be delayed or prevented through a healthy lifestyle. (Olokoba et al, 2012)The common symptoms of diabetes are increased thirst,
increased hunger, dry mouth, frequent urination or urine infections,
unexplained weight loss the main symptoms includes excessive fatigue, blurred
vison and headaches are the common sign of diabetes. Cuts and wounds
take longer to heal. These are the main signs and symptoms of diabetes. (Clark et al, 2007)

Oral and
injectable diabetes medications work in numerous ways to stimulate the
production of insulin and the absorption of insulin, into the cells to reduce
the output of glucose from the liver. (Moller et al,2001) Also to slow the absorption of
carbohydrates, and even to spill extra glucose out of the kidneys. At a certain
point in the progression of diabetes, insulin or insulin in combination with
the other oral diabetes medications is necessary to control blood glucose
levels. (Skamagas et al, 2008). Hemoglobin is a protein that is initiate
within red blood cells, its function to carries oxygen throughout the body,
when hemoglobin combines with glucose in the blood it come to be glycated, also
known as HbA1c. (Florkwoski, 2013) The Haemoglobin (HbA1c) are distributed in two
categories, and they remain divided in the method based on the charge
differences and methods based on the structural differences Ion-exchange
chromatography and electrophoresis come under the first category moreover while
immunoassay, enzymatic assay and affinity chromatography come under second
category therefore the routine of Haemoglobin (HbA1c) (Sherwani et al, 2016).



The overall aim for this report is to discuss if HbA1c is an effective
technique in the diagnosis of Diabetes Mellitus. Furthermore, mentioning the
limitations of HbA1c as a potential diagnostic tool and whether there are any
possible limitations in specific scenarios (Barman et al, 2012). HbA1c is an analytical tool that is used to
check on the belongings of exercise or precise diet on diabetes and reliant on
the results. (Peters et
al 1996). Glycated
haemoglobin (HbA1c) was initially recognised as an ‘abnormal’ molecule in
diabetic individuals. (Hinzmann et
al 2012). However, it was not accurate until proper
experiments and trails were prepared and tested. Recently there has been significant
attention drawn in the use of HbA1c as an analytical tests for diabetes as well
as the screening test for individuals who are at high risk of diabetes (Akande, 2016) HbA1c is
acknowledged as the haemoglobin in the blood that is bonded to glucose
molecules. Advanced red blood cells are anucleate cells because they lack a
nucleus and additional membrane bound organelles. This allows the maximum
amount of haemoglobin to fully coat the erythrocyte (Anon, 2017).  Haemoglobin is a pigment responsible for the
red colour of blood. Approximately 90% of the haemoglobin is adult (A) type and
furthermore about 8% of this A type haemoglobin is prepared from molecules
called A1a1, A2a2, A1b, A1C. When glucose levels are not controlled and there
is an increase in glucose levels, the glucose molecule begin to bind to
haemoglobin A1C, resulting in glycated haemoglobin (HbA1c). (IMAGAWA et al, 1984) Therefore, the levels of HbA1c in the blood indicate the
average quantity of glucose, with an increase in HbA1c levels indicating an
increase in glucose levels in the blood. (Rohlfing et
al, 2012). This allows us to monitor the glucose levels
and see if they are high or have been high recently. Red blood cells have a
lifespan of 120 days (8-12weeks) henceforth; the HbA1c is a beneficial
indicator to evaluate how well the diabetes is controlled of an induvial in the
last 8-12 weeks. (Diabeticretinopathy, 2005) 


Figure 1: Summary of Diagnostic Criteria for Diabetes
Mellitus (Fitriani,



As mentioned earlier the haemoglobin contains
the range of molecules. Nevertheless, to distinguish A1c from additional
haemoglobin molecules there is an electrical charge existent on the A1c
molecules (to which the glucose binds). (Koval et al, 2011) In addition,
there is a difference in size. There is a special method called the high-pressure
liquid chromatography (HPLC) this takes advantage of these differences between
A1c and other haemoglobin molecules; to divide A1c. (Weykamp et
al, 2009). In order to
perform the HbA1c test, a blood sample is taken from a specific individual. Due
to HbA1c levels being unaffected by temporary changes in glucose levels, (like
right after consuming a meal), HbA1c levels can be used. (Alferness et al 2009),
correspondingly fasting for the blood test is not essential. Firstly, when the
test is performed, the blood is taken out of the individuals arm in the surgery
and after this; it is sent off to the laboratory. (Hirst et
al, 2014) The results of
the test indicates the stability of the patients’ blood glucose concentration,
which then allows for the planning of a particular treatment plan according to
the patient. However, the
HbA1c is a suitable test, it is not necessary to require any specific
preparation e.g. fasting, this can take in a suited place like hospitals
clinics/surgery, and analysing the HbA1c this shows how the
high blood glucose has been on average over the last 8-12 weeks. (Renard 2005)


Whilst HbA1c tests are usually
reliable, there are some limitations to the accuracy of the test, since this
particular test does not reveal the blood glucose levels. (Linden,
2006) The average normal levels of the HbA1c in a non-diabetic individual are
about 36mmol/l (5.5%). In a diabetic 48mmol/l, (6.5%) it is considered
conventional. Typically, a level of 6.5% indicates that the individual has
diabetes. (Sacks et al., 2002). The purpose of the HAb1c to keep
HbA1c levels of diabetics under 7% to avoid the possibility of complications
which include eye problems, nerve damage, kidney disease and heart disease.
(Bennett et al, 2007).These are just the approximates due to the level
of HbA1c in every diabetic contrasts as to the factors for example begin
underweight and overweight. The usual set target is <59 mmol/mol (7.5%) are at the possibility of developing severe hypercalcemia. (Miller et al, 2015). People with forms of anaemia may not have appropriate haemoglobin for the test to be precise and may need to have a fructosamine test instead. (Radin, 2013)  Also being pregnant or having and rare form of haemoglobin (known as a haemoglobin variant) can also return an inaccurate HbA1c, while readings can also be affected by short term issues for example illness as they can cause a temporary rise in blood glucose. (Thevarajah et al, 2010)  Because of the way, the HbA1c test measures blood sugars, if you higher blood sugar levels in the weeks leading up to your HbA1c test will have a greater on your test result than your glucose levels 2 to 3 months before the test. (Jia et al, 2016)   HbA1c mmol/mol % Normal Below 42 mmol/mol Below 6.0% Prediabetes 42 to 47 mmol/mol 6.0% to 6.4% Diabetes 48 mmol/mol or over 6.5% or over   Figure 2: This diagram shows how HbA1c can indicate people with prediabetes or diabetes.(, 2018)                      Conclusion Although this test is a convenient test, yet it's not a perfect diagnostic test. This due to the fact when some people who are diagnosed as having diabetes based on this specific test they will actually not have diabetes (false positive) and on the other hand, those who are not diagnosed might be under risk of having diabetes (false negative) (, 2017). Henceforth regardless, off WHO approving the use OF HbA1c as a diagnostic check, this test is not a 100% reliable. This is because this test cannot used to monitor routine glucose concentration or even detect the everyday presence or absence of hypoglycaemia or hypercalcemia. (Chua et al 2014)  Other limitations of HbA1c as a diagnostic contrivance is that it can be affected by conditions that effect haemoglobin, such as anaemia and also supplements such as vitamin C and E, similarly high cholesterol levels.(Ahmad et al 2013). Moreover, kidney disease and liver disease may also affect the result of an HbA1c test. This may explain why it will detect some patients as having diabetes when they actually do not and vice versa. This specific test is organised at least once a year and is recommended in addition to home blood glucose monitoring. (Kuo et al, 2016)