Monday Medical: Health fair to offer glucose test

Hemoglobin A1C called 'gold standard' of diabetes management

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— At next week's early blood draws and at the Oct. 24 Yampa Valley Medical Center Community Health Fair, we will offer hemoglobin A1C as an additional blood test.

Because we already have received questions and expect to hear more, this column will explain the importance of this test and what it measures.

Hemoglobin A1C also is called "glycosylated hemoglobin," "HbA1C" or simply "A1C." It is a blood test that measures the average glucose in someone's blood during the past two to three months.

It is actually not a true average because about half the result reflects the 30 days just prior to the test, while the other half reflects the previous two months. However, it is easier to understand it in terms of an average, which is why we use that word.

Hemoglobin is a protein in red blood cells that carries oxygen. Glucose attaches to hemoglobin and remains attached for the life of the red blood cell, which is about 120 days.

Someone with diabetes (types 1 or 2) manages his or her disease on a daily basis by making food choices, exercising, taking medications, managing stress and monitoring blood glucose levels. Hemoglobin A1C is often referred to as the "gold standard" of diabetes management because it is the best way to get feedback on how all this is going.

Are the daily management efforts working? Does something need to be adjusted? Hemoglobin A1C provides a big-picture look at diabetes management, while home blood glucose monitoring is a snapshot of one point in time.

Hemoglobin A1C does not replace home blood glucose monitoring; however, these numbers help people with diabetes make specific decisions about their diabetes management.

Generally, people with diabetes have their hemoglobin A1C measured every three months. If someone's blood glucose levels are stable, it is acceptable to have a hemoglobin A1C checked every four to six months.

For someone who does not have diabetes, a normal hemoglobin A1C level would fall between 4 and 6 percent. The recommendation for people with diabetes is to keep their hemoglobin A1C below 7 percent.

The results of a large research study, published in 1993, showed that people who keep their hemoglobin A1C level close to 7 percent have a decreased risk of long-term diabetes complications. When the hemoglobin A1C level is above 7 percent, it is time to consider making adjustments in the diabetes management plan. Recommendations are different for children.

Blood can be taken from a vein or a finger, depending on the type of equipment the lab has available for measuring hemoglobin A1C. This blood test does not require fasting because the test is not affected by what the person does on the day it is drawn, such as consuming food or exercising.

Up until now, hemoglobin A1C has not been used to diagnose diabetes. If the result is elevated above the normal range, we know something is off; however, if the result is normal, it could be missing elevated blood glucose levels at a particular time of day.

For instance, many people with Type 2 diabetes have elevated fasting blood glucose levels, but the rest of the day their levels are normal. Because the overall "average" may come out fine, the hemoglobin A1C could show up as normal.

Health care professionals are discussing this issue and working on a decision regarding use of hemoglobin A1C as a diagnostic tool. In the meantime, people with pre-diabetes (fasting blood glucose between 100 and 125 mg/dL) can have a hemoglobin A1C test done to see what is happening in the big picture.

We now have a conversion chart to help patients and families understand the hemoglobin A1C result better. This chart will be available at YVMC's Diabetes Education Program booth at the Oct. 24 Community Health Fair, where we will be happy to answer questions.

Jane K. Dickinson, RN, PhD, CDE, is the Diabetes Education Program director at Yampa Valley Medical Center.

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