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For 30 years, diabetes specialist John Hunt, MB, BS, FRCP, has been trying to get his patients at the University of British Columbia to understand the importance of good control. Nothing worked, until six months ago, when Hunt hung this sign in his office:
"If you don't want to go blind, keep your HbA1c under 8%."
As soon as people see this, they ask, "Really? What's my HbA1c?"
Nothing has captured their attention like this sign, which drive home the message that their health is at risk. "Seeing is believing," says Hunt, who says that talking to his patients was not as effective as the sign.
It is simple. If your HbA1c percentage is in an acceptable range, your chances of diabetes complications are greatly reduced. With every percentage point above normal, the chance of diabetes complications increases tenfold. Still, under 20 percent of people with diabetes actually test their HbA1cs quarterly.
What is the HbA1c?
More than everyday glucose values, the HbA1c test tells a more complete story of diabetes control. As glucose travels through your body, it attaches itself to your hemoglobin, which is a protein inside your red blood cells. When glucose connects itself to hemoglobin molecules, the process is called glycosylation or glycation.
When your BGs are high (even after your meter says you are back to normal), some glucose will stay attached to your red blood cells. So, the more often your body has high glucose levels, the more glucose will attach to the hemoglobin. The red blood cells only live for about three months and are then replaced by new red blood cells. Thus, when you measure every three months how much glucose is attached to red blood cells, you get a quarterly average of your glucose levels.
Once glucose and red blood cells are attached, they are known as glycated hemoglobin. This is the same action that cures meat to make beef jerky. Beef jerky is tough, not easily penetrated by bacteria and does not decay. These may be good qualities for a food product, but not for the human body. It is these jerky-like substances that interfere with blood flow and contribute to diabetes complications. Called advanced glycated endproducts (AGEs), they eventually make cells so stiff that they do not work.
The good news is that if you know your HbA1c is out of range, you can work to improve control and avoid complications. The bad news is that less than 20 percent of people with diabetes actually get their HbA1cs checked quarterly.
Family Practitioners Don't Know Their HbA1cs
Hunt knows diabetes care inside and out. Unfortunately, not every patient sees a diabetes specialist like Hunt.
The DCCT (Diabetes Control and Complications Trial) established the connection between HbA1c and complications back in 1993, saying that the risk of complications can be reduced by 60 percent by normalizing BGs. But six years later, many people with diabetes are still not getting the recommended four HbA1c tests per year. Even worse, many doctors do not know the importance of the HbA1c measurement.
Journal of Family Practice reported in 1997 that most type 2s see their family doctors for diabetes care. These general practitioners face the challenge of knowing not only the latest diabetes information, but also news of the thousands of other conditions they treat. Both doctors and patients need to be educated on quarterly HbA1c testing for all people with diabetes.
The Home HbA1c
Home HbA1c tests can ease the process. With a doctor's prescription, patients order tests by telephone or Web, and receive a kit in the mail. With one finger stick the test is done and they mail it to a laboratory (or visit their own laboratory, depending on the test). Results are sent back to the consumer and the consumer's physician. Most states' laws prohibit selling home tests to patients without a doctor's prescription.
Telling the HbA1c Story
Yet, not many HbA1c prescriptions are being written. If everyone were getting the message, then they might be getting their quarterly tests, or at least asking their doctors to perform an HbA1c in the office. It is tough to say whose job it is to get out the HbA1c message.
Art Williams is president of Diabetes Technologies, one of the smaller firms that manufactures a home test. Williams calls for HbA1c awareness on a community level.
"Who should be doing this missionary work?" wonders Williams. He believes it should come on many levels. The American Medical Association should aggressively inform doctors about HbA1c testing, and local pharmacies should provide diabetes consumers with HbA1c information. Health maintenance organizations (HMOs) should also join the fight. Williams constantly looks for media through which he can get out the HbA1c message.
Another home test manufacturer, BioSafe, is partnering with large diabetes organizations to launch a national education campaign about the importance of complying with quarterly HbA1c testing. BioSafe will distribute its tests to doctors across the country, send brochures and other materials to pharmacies, schools and doctors, and also produce an educational video on HbA1c testing.
Express-Med makes a home HbA1c test, and also sells mail-order diabetes supplies, using this platform to sell people and professionals on quarterly HbA1c testing.
"We see this as part of our responsibility," says Alan Scantland, Express-Med's product manager for its HbA1c test. Whenever the company calls on professionals to promote its products, the HbA1c test is a big part of the story, according to Scantland.
The Big Guys
Roche Diagnostics, a huge manufacturer, sells its HbA1c test, the Accu-Chek A1c, only to managed care organizations. HMOs buy large quantities of the tests to send to their patients with diabetes. The patients mail in test results, which are then shared with physicians.
Becton Dickinson, a large manufacturer of diabetes supplies, got out of the home HbA1c market. It recently discontinued its home HbA1c test because state laws got in the way. Barry Ginsberg, MD, PhD, Becton Dickinson's medical director, says that because it is a diagnostic test, states require a prescription.
"This makes it harder for the patient to get an HbA1c test," says Ginsberg.
Becton Dickinson did get the Food and Drug Administration (FDA) to approve its HbA1c test as a nonprescription item, but state laws take precedence over federal laws, so FDA approval means little.
"We tried to get the FDA to intervene, and they didn't," says Ginsberg.
The frustration became too much for Becton Dickinson. Until there are changes, says Ginsberg, the company will stay out.
"I'm really sorry it did not work out," says Ginsberg. "In five years, when states change these laws, we will bring back the home product."
Even with over-the-counter status, Ginsberg promises that Becton Dickinson will always send results to a patient's health care professional. "That's very important," he says. "Without notifying a doctor, you have calamity."
James R. Hansen, MD, FAAP, medical director at the Emanuel Children's Diabetes Center in Portland, Oregon, says that if you do an HbA1c test at home, and your result is over 8%, then you have to make changes.
"Those changes really should be done with your health care team," says Hansen.
More Than A Number
Although it is the number-one indicator of diabetes control, the HbA1c test is not the complete picture.
"Even if your HbA1c result is good, it does not mean that treatment is optimal," says Bruce Zimmerman, MD, president of the American Diabetes Association. "You could have a good HbA1c, but you could still be having frequent hypos."
An in-range HbA1c test is not a reason to skip other tests, warns Zimmerman. "A good result may cause a patient to put off an eye exam or microalbumin testing," he says, "and this does a great disservice to a patient."
Patients (and doctors) can misinterpret HbA1c tests, and can run into even more trouble from not knowing exactly which test they are interpreting.
9% HbA1c? Is That Good?
The HbA1c test is not the only test that gives a three-month average, but it is the most common. The category of glycohemoglobin (GHb) tests, of which there are several different types, includes the HbA1c. Each tells you the same information, but the normal range can be different. A 9% result is a good score for one test, but too high for another. The acceptable range depends on which assay, or test, is used.
Many in the health care field are calling for all tests to use the same assay, with the same normal range. Toward this end, a group of leading diabetes doctors formed the National Glycohemoglobin Standardization Program (NGSP), calling for all laboratories to use an assay on the same scale as the one used in the DCCT.
"The DCCT...provided a large body of data relating glycohemoglobin values to mean blood glucose," says NGSP network coordinator Randie Little, PhD, of the University of Missouri. "Thus, the DCCT results set the stage for establishing specific diabetes treatment goals using GHb as an index of mean blood glucose."
In addition to using the same target ranges, NGSP-sanctioned methods must meet its criteria for precision and accuracy. The ADA has positioned itself with the NGSP, warning people with diabetes that "data should be used with caution if the GHb assay method is not certified as traceable to the DCCT reference method."
If you get a glycohemoglobin test result, make sure you know the normal range. It is widely agreed that a value within 1 percentage point of the nondiabetic range is acceptable for people with diabetes.
Stepping up the sophistication of diabetes care a little further is the fructosamine test, which can be obtained without a prescription. The fructosamine test measures two-week averages of glucose control. It measures the glycosylation of different proteins.
Along with hemoglobin, albumin and globulin are two other proteins in the blood, which also become glycosylated when glucose levels are high. The glycosylation of albumin and globulin produces fructosamine. While hemoglobin proteins live for three months, albumin and globulin have two-week life spans.
LXN Corporation has just released a new combined glucose meter and fructosamine tester. Called the In Charge, it reads fructosamine results, which the company calls the glucoprotein test. The In Charge uses one strip for glucose levels and a different strip for fructosamine measurement. A fructosamine test takes about four minutes.
To describe the In Charge, David Keleman, LXN's vice president of marketing, uses a classroom analogy.
"If glucose testing is a pop quiz and the HbA1c is a final exam, then the fructosamine test is the midterm," says Keleman. "The glucoprotein [fructosamine] test helps you along the way, so that you don't fail the final exam."
Keleman warns that the fructosamine test does not eliminate the need for quarterly HbA1c testing. Rather, it enhances everyday glucose and HbA1c results.
Another key to the fructosamine test is never relying on just one result. According to Keleman, one out-of-range result merely warns of trouble. Look at the next test for guidance, to see if a trend develops.
"If your trend is going the wrong way, meet with your health care professional," says Keleman. "Never take action based on just one value."
Once changes are made, results can be seen in two or three weeks with a fructosamine test, giving a head start for an HbA1c test.
LXN hopes that consumers will see the added fructosamine test as an advantage over ordinary meters, opening a new age of glucose testing. Medical professionals are still trying to figure out how fructosamine testing will figure in diabetes care.
"Generally, fructosamine has not become the gold standard test, " says Zimmerman, "because all of the major clinical trials use HbA1c. It is harder to put fructosamine in the context of how a patient is doing."
Hansen agrees that it is not a widely used indicator.
"It is a less expensive test," he notes, "so some health systems are using it. The concern is that fructosamine is not as well characterized as HbA1c to look at control and risk of complications."
Hansen agrees with LXN's recommendations, that you should still get HbA1c tests, adding that fructosamine "is a good way to make adjustments before three months."
Conditions Interfere with Accuracy
With either the HbA1c or fructosamine test, abnormalities in a person's hemoglobin will cause false readings. Before relying on results, you must be sure that you have no condition that would prevent an accurate test.
Anemia, a common condition characterized by a low red blood cell count, can make a test invalid. The same goes for polycythemia, which is a state of too many red blood cells. In addition, steroids and other drugs can interfere with an HbA1c test. Williams warns that many other factors affect results, including: recent bleeding, hemorrhage, high reticulocyte (a type of blood cell) count, extremely high bilirubin, steroids, dehydration, anti-coagulant drugs, heavy alcohol consumption, high doses of aspirin, plus others.
Williams says that his company's test, the Diabetes Technologies Accu-Base A1c Test Kit, will detect these abnormalities, and will not give a reading if a person's red blood cell count differs from the norm.
Express-Med's test, the A1c-Express, will reveal hemoglobin abnormalities to the laboratory professional, who will then notify the individual and his or her doctor. The A1c-Express kit sends a chromatogram to the prescribing physician. The chromatogram reveals hemoglobin abnormalities, so the physician can warn the patient of a problem.
BioSafe makes the Hemoglobin HbA1c Test Kit, which shows accuracy up to a 20-percent hematocrit level. Hematocrit levels reflect hemoglobin abnormalities, with a normal human hematocrit level being roughly 40 percent. Thus, says BioSafe, unless a person has severely low levels, its test will be accurate. "A person with hematocrit lower than 20 percent should already be seeing a physician," says Tracy Surufka, RN, of BioSafe's technical support department.
"The HbA1c test is a complement to a physician's care. Patients should never get an HbA1c without a physician's support," says Surufka. "Patients with diabetes are constantly monitored, so a doctor should catch anemia."
When considering the use of a glycated protein test such as HbA1c, you should be aware of any abnormal condition or interfering substance that might affect the accuracy.
Whether using a home test or going through a doctor's office, the message is clear. The HbA1c test is the path to diminish chances of long-term complications. Right now, many patients seem to be in a difficult situation. They must get HbA1c advice and review it with their doctors, but their doctors may not know enough to prescribe the tests. Until all physicians are informed of its importance, it will be up to patients to secure quarterly HbA1c testing. The key is to use professional help to interpret HbA1c results, and make sure it helps you toward the goal of reducing your complication risks.
1 comment - Oct 1, 1999