What is GlycoMark?
GlycoMark
is a newly FDA-approved blood test for the intermediate-term monitoring
of glycemic control in people with diabetes and measures 1,5-anhydroglucitol (1,5-AG) in serum or EDTA plasma. GlycoMark monitors mealtime spikes over 2 day to 2 weeks in a single, convinient blood test and provides complementary information to A1C to highlight and manage transient glycemic excursions (postprandial hyperglycemia).
What is 1,5-AG? How does it work?
1,5-AG
is a monosaccharide that is similar to glucose and is ingested through
food, building a large body pool that remains in equilibrium in normal
subjects.
Normal mean value in serum is;
17.7µg/ml for females, and
22.5µg/ml for males.
Due
to the similarity in structure to glucose, reabsorption of 1,5-AG in
kidney is prevented by the glucose excreted in urine, resulting in
rapid net decrease of 1,5-AG. Therefore, serum 1,5-AG decreases rapidly in people with hyperglycemia above the renal threshold of glucosuria. Upon return of strict glycemic control (no glucosuria), serum 1,5-AG levels recover at a daily rate of 0.3µg/ml.
What are the suggested ranges of GlycoMark?
Although
the normal range for GlycoMark is relatively wide, values under 10µg/ml
are indicative of elevated postmeal glucose levels in moderately
uncontrolled patients (A1C 6.5 to 8.0%).
|
GlycoMark (µg/ml) |
Assessment of Diabetes |
|
14 or Higher |
Normal (Healthy) |
|
10.0-13.9 |
Well-Controlled |
|
6.0-9.9 |
Moderately Uncontrolled |
|
2.0-5.9 |
Poorly Controlled |
|
1.9 or Lower |
Very Poorly Controlled |
How do I interpret GlycoMark values?
It is important to note that GlycoMark values decrease when serum glucose levels increase (hyperglycemia).
In otehr words, increase in 1,5-AG would indicate improvement, and
decrease would indicate worsening of glycemic control. Upon return of better glycemic control, 1,5-AG increases at a constant rate of 0.3 ug/ml. This consistent recovery rate in 1,5-AG levels provides a rapid indication of the patient's response to treatment.
Who needs the GlycoMark test?
Given
the sensitive and rapid response to even transiently ascending serum
glucose levels, GlycoMark is important in maintaining near-normal serum
glucose levels. As an intermediate term
monitoring tool of glycemic control, GlycoMark reflects more recent
glycemic status (1-2 weeks) and may allow patients to seek medical
intervention in a timelier manner. As GlycoMark also measures postprandial hyperglycemia, the test provides an additional level of glucose maintenance. Measuring mealtime
spikes is particularly important in patients who are seemingly in
good control. The GlycoMark test may also be used in situations where
the A1C test cannot be measured or may not be useful (e.g.,hemolytic
anemias).
How should GlycoMark be used with A1C to manage diabetes ?
When
fasting glucose values are coming into target range but A1C levels are
still suboptimal (A1C 6.5 to 8.0%), monitoring of postprandial
hyperglycemia by GlycoMark is key to achieving optimal glycemic
control. In the clinical setting, GlycoMark may be used as a complement to A1C testing, not as a replacement to it. For
example, you first use A1C to identify patients who are moderately
controlled, and then use GlycoMark to determine differing postmeal
glucose levels.
What clinical studies have been conducted on GlycoMark?
The 1,5AG test has been available in Japan since 1991 and there have been several published studies confirming the clinical utility of 1,5AG. Recently, a major clinical study was conducted at University of North Calorina and University of Rochester. The study found that 1,5-AG reflects postprandial hyperglycemia to a greater extent than A1C and FA. Postprandial
hyperglycemia may exist in patients with modest A1Cs, and 1,5-AG may be
used as a complementary marker to A1C for determining overall diabetes
control. More information on the study can be found in the Clinical Data section.
How should I use GlycoMark with pharmaceutical therapies? Are drug companies using GlycoMark?
As
a sensitive indicator of postprandial hyperglycemia, the GlycoMark test
can be useful in monitoring treatments aimed specifically at lowering
postmeal glucose levels (such as fast acting insulins which target
after-meal glucose levels). Yes, major pharmaceutical companies are using GlycoMark in clinical studies.
Has GlycoMark been approved by the FDA?
Yes,
the test has received 510(k) marketing clearance and is indicated for
the intermediate term monitoring of glycemic control in people with
diabetes.
Where do I order the test?
The laboratory service for GlycoMark test is currently available at:
- LabCorp (Order code: 500115) Phone: 800-762-4344, www.labcorp.com
- Esoterix Inc. (Order Code: 500609) Phone: 800-444-9111, or www.esoterix.com
- Specialty Laboratories (Order Code: S51094) Phone: 800-421-4449, www.specialtylabs.com
How can I get reimbursement for GlycoMark?
There
is an already existing CPT code which is being used (84378 - for sugars
testing) and the reimbursement level is $15.90. Reimbursement is
being arranged with private carriers.
Where can I get additional information on GlycoMark?
Call 888-744-0221 or email us (see "Contact" page).
Also, refer to the
following review paper for more information: Buse J, Freeman J, Edelman
S, Jovanovic L, McGill J: Serum 1,5-Anhydroglucitol (GlycoMark): A
Short-Term Glycemic Marker. Diabetes Technology & Therapeutics
2003; 5:355-363.
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