understand that staying ahead of the
progression of the disease and associated
comorbidities; minimizing the financial
implications of disease progression; and
improving patient outcomes and quality
of life are dependent on the proactive
screening for and management of at-risk
patients. Laboratory and point-of-care
testing (POCT), therefore, play a critical role
and bring significant value in the screening,
monitoring, and management of diabetes.
Through the power of diagnostic
testing, a patient’s chronic condition can be
kept in balance and not allowed to escalate
to a critical state that lessens quality of life
and may require hospitalization and more
expensive intervention. Defining diabetes
has shifted to the laboratory, as symptoms
alone (excessive thirst, frequent urination)
are often not adequate for evaluating the
presence or the progression of the disease.
Laboratory Test Methodologies
Predominantly, two testing methods are
used to diagnose and monitor diabetes:
fasting plasma glucose (FPG) and
hemoglobin A1c (HbA1c) testing.
Both testing methods have their strengths
and weaknesses, and proper understanding
of the pros and cons of each enables
appropriate application of the right test
at the right time for better overall
diabetes patient management.
“ Lab and point-
of-care testing
play a critical
role, and bring
significant value
in the screening,
monitoring, and
management of
diabetes.”
Irwin Z. Rothenberg, MBA, MS, CLS(ASCP)
is measured two hours after a measured
dose of glucose is administered orally. The
glucose levels are another determinant of
potential or existent diabetes.
which results in more effective patient care.
HbA1c testing considerations
While there are some factors that
interfere with FPG testing, interference
Hemoglobin A1c
related to HbA1c testing is more
complex. Hemoglobin variants and
Introduced in the late 1970s, HbA1c
analytical variables can interfere with
testing offers a measurement of longer-
HbA1c measurements, as well as the
term
glucose
metabolism.
As
hemoglobin
Fasting Plasma Glucose
interpretation of results, leading to
circulates
through
the
body,
glucose
in
FPG testing measures short-term glucose
serious implications for both patients
the
serum
reacts
with
an
amino
acid
metabolism, indicating blood glucose
and the clinicians caring for them.
group
on
hemoglobin
in
proportion
to
levels at a given time. To get an accurate
the
amount
of
glucose
in
the
circulation.
baseline glucose measurement, patients
This glycated hemoglobin, measured as a Hemoglobin variables
are required to fast at least eight hours
Hemoglobinopathies are genetic
prior to the test. Factors that can affect test percentage of total hemoglobin, thus
serves
as
an
indicator
of
how
much
variants that affect the structure of a
results include acute illness, stress, and
glucose
is
in
the
blood.
A
test
result
>6.5
patient’s hemoglobin, which, in turn,
exercise, as well as patients who have not
percent
HbA1c
indicates
diabetes.
can impact an HbA1c test. There are
complied with fasting requirements. An
hundreds of types and subtypes of
FPG of less than 100 mg/dL is
hemoglobinopathies; most of them
considered normal, while a reading
do not seem to have any physiological
above 126 mg/dL puts a patient in the
consequences nor an effect on
range for diagnosis of diabetes (Table 1).
HbA1c testing. Others are clinically
significant. These include HbS
Random (non-fasting) Plasma
(sickle cell), HbC, HbD, HbE and
Glucose
HbF (elevated fetal hemoglobin).
While not ideal for diabetes diagnosis
Hemoglobin variants can cause
and management, there is also a place
Table 1. HbA1c, Fasting Plasma
some HbA1c tests to give false high or low
for random (non-fasting) glucose
Glucose, and 2 hour Post-prandial glucose results, leading to treatment that is
testing in giving physicians and
inadequate or too aggressive. Laboratory
level test ranges and Interpretations.
patients quick results regarding the
personnel should work with physicians to
Despite its widespread acceptance and
current blood glucose state. It is most
use, HbA1c is not a replacement for FPG understand patients’ underlying conditions
appropriate in managing acute episodes testing in managing diabetes. FPG is a
and inform them that results must be
(acute hyperglycemia or hypoglycemia). measure of short-term glucose levels,
interpreted with these factors in mind. For
Normal result: 70-125 mg/dl.
example, offering a report that...
while HbA1c is a measure of average
long-term glucose levels. Thus, neither is
The Two-Hour Postprandial Oral
Read the rest of this and other articles at
a replacement for the other. Understanding
Glucose Challenge
www.PhysiciansOfficeNews.com
each test, and their potential interferences,
Another option is where the blood glucose ensures proper use and interpretation,
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