The A1C is certainly the gold standard to see how well we are controlling our diabetes. But even gold isn't good enough for us.
The A1C doesn't show our glycemic variability. For those of us who have our blood glucose levels under reasonably good control, our glycemic excursions are even more important than our average level.
A low A1C level can mask a lot of lows and highs. The experts call these hypos and hypers "glycemic variability" or "glycemic excursions." Our level can be all over the place, while our A1C looks fine.
"Excursions are very important in terms of diabetic complications," says Donald Bergman, M.D, "because that's what triggers the oxidators, the inflammation of the blood vessels, the whole cascade of complications." Dr. Bergman is a leading endocrinologist who spoke to the press at last month's convention of the American Association of Clinical Endocrinologists, or AACE, in Houston.
A new way for us to find out our excursions or glycemic variability got a lot of attention both at the AACE convention and this month's convention of the American Diabetes Association in New Orleans. It's the GlycoMark test from GlycoMark Inc. in Winston-Salem, North Carolina.
While I wrote about it four years ago in Diabetes Health magazine and then three years ago here, the GlycoMark has been slow to catch on with our doctors. Until now.
After all, we have other ways to find out how much glycemic variability we have. We can do fingerstick tests two hours after the first bite of every meal, and we can even analyze our numbers with some blood glucose meters -- if we give those meters lots of data. The WaveSense Jazz blood glucose meter from AgaMatrix Inc. in Salem, New Hampshire, incorporates "glucose variability tracking." The Accu-Chek Smart Pix Device Reader incorporates indexes that some people think will help. These are the low blood glucose index and the high blood glucose index that Dr. Boris Kovatchev, associate director of the University of Virginia Center for Biomathematical Technology, developed.
Wearing one of the continuous blood glucose monitors from Medtronic Diabetes, DexCom Inc., and Abbott Diabetes Care will also tell us how wild our levels might be. But few of us do fingerstick tests regularly enough to determine our glycemic variability. And even fewer of us wear a continuous blood glucose monitor.
Enter the GlycoMark. Each time we test with it, the GlycoMark reflects the previous two weeks of our after-meal levels. When I interviewed GlycoMark President Eric Button, he told me that it is available through all the major laboratories that our doctors use. While they don't have a home test kit yet, Eric told me that they have it in development.
A research study presented Saturday at the American Diabetes Association convention established that the GlycoMark test accurately shows our blood glucose swings. The abstract of the study, "1,5 AnhydroGlucitol Concentrations and Measures of Glucose Control and Glucose Variability in T1DM and T2DM Patients," is available online as Abstract 882-P.
The study shows that the GlycoMark test is a particularly good check for those of us whose A1C levels are less than 8 percent. Previous studies found that as many as 40 percent of people with type 2 diabetes who have A1C's of 8 percent or less "experience glucose swings that need medical intervention," Eric says.
Dr. Bergman told me that he is now ordering it on all of his patients who have diabetes. "I like the concept that it specifically reflects postprandial sugar," he says. "While I haven't made up my mind about the GlycoMark yet, I want to get a sense, independent of what the literature says, on how effective it is in correlating to their fingerstick tests four times per day."
Meanwhile, Endocrinologist Nancy Bohannon, M.D., was already prescribing the GlycoMark test to her diabetes patients when I interviewed her four years ago for my Diabetes Health article. She directs clinical research at St. Luke’s Hospital in San Francisco.
A few days ago I asked her if she still prescribes the GlycoMark test. "Absolutely," she replied. "Every time I order an A1C now. This is assuming that they have A1Cs that are under 7. If you use it on people whose A1Cs are 8 or great, it is a waste of money and blood. But for people who are trying to get tight control, it is a very good reflections of their post-prandial blood sugars."
Alan Garber, M.D., is another endocrinologist who has been prescribing the GlycoMark test to some of his patients for several years. He is a professor of medicine at Baylor College of Medicine in Houston. Dr. Garber told me that the GlycoMark is most useful for people with A1C levels between 6 and 8 percent.
He agreed with me that most doctors -- much less those of us who have diabetes -- haven't even heard about the GlycoMark test yet. But that's about to change, especially when you ask your doctor to prescribe it.