HEMOGLOBIN - THE TEST THAT NEVER FORGETS
Because you have diabetes, you and your
endocrinologist, diabetes educator and other members of your
health care team work to keep your blood glucose at ideal
levels. There are two powerful reasons to work for effective
blood glucose control:
1 You will feel better
2 You may prevent or delay the start of
diabetes complications like nerve, eye, kidney and blood vessel
One way to keep track of your blood glucose
changes is by testing your blood glucose at home. These tests
tell you what your blood glucose level is at any one time.
But suppose you want to know how you have
done overall. There's a test that does this. A glycated
hemoglobin test (HbA1c) gives you a picture of your average
blood glucose control for the past two to four months. This test
must be done by a laboratory but the results give you a good
idea of how well your diabetes treatment plan is working.
In some ways the glycated hemoglobin test
is like a baseball player's season batting average. Both
glycated hemoglobin and the batting average tell you about a
person's overall blood glucose (or batting) success. Neither a
single day's blood test results, or a single game's batting
record, give the same big picture.
How it works
You know from the name that the test
measures something called glycated hemoglobin. You may wonder
what it has to do with your blood glucose control.
Hemoglobin is found inside red blood cells.
Its job is to carry oxygen from the lungs to all the cells of
the body. Hemoglobin like all proteins links up with sugars,
such as glucose. When you have uncontrolled diabetes you have
too much glucose in your bloodstream. This extra glucose enters
your red blood cells and links up (or glycates) with molecules
The more excess glucose in your blood, the
more hemoglobin gets glycated. It is possible to measure the
percentage of glycated hemoglobin in the blood. The result is an
overview of your average blood glucose control for the past few
How does the
glycated hemoglobin test look backward?
Suppose your blood glucose was high last
week. What happened? More glucose got hooked up with your
hemoglobin. This week, your blood glucose is back under control.
Still your red blood cells carry the "memory" of last week's
high blood glucose in the form of more glycated hemoglobin. This
'record' changes as old red blood cells in your body die and new
red blood cells (with fresh hemoglobin) replace them. The amount
of glycated hemoglobin in your blood reflects average blood
glucose control for the past two to four months, or the lifespan
of a red blood cell.
In a person without diabetes, about 5% of
all hemoglobin is glycated. A HbA1c level of more than 8%
indicates unacceptable control. 7-8% indicates suboptimal
control. A level of less than 7% is desirable. In bad cases, the
HbA1c can go as high as 20%. But while the glycated
hemoglobin test is an important tool, it can't replace daily
self-testing of blood glucose. Glycated hemoglobin tests don't
measure your day-to-day control. You can't adjust your insulin
on the basis of your glycated hemoglobin tests.
Glycated hemoglobin tests can help:
• Confirm self-testing results or blood test results by the
• Judge whether a treatment plan is working.
• Show you how healthy choices can make a difference in diabetes