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eAG (estimated Average Glucose) = Glucose Standards War

For at least three consecutive years now at the annual ADA Conference, we keep hearing about a rumored switchover from the A1c as the gold standard average glucose measurement. Instead, we’ll get something new and supposedly easier to understand: a new measure that more closely reflects the mg/dL (and international mmol/l) numbers we all get on our home glucose meters. This new test is now dubbed the eAG (estimated average glucose).

One of the big news announcements Scientific Sessions this week was the results of a large international study that supposedly underscores the accuracy of the eAG. In this 10-center study, 507 volunteers with diabetes had their A1c translated into eAG readings and compared with their running daily BG results, if I understood the press materials correctly. “Study investigators found a simple linear relationship,” the ADA press release states.

Also stated: “Patients find it difficult to relate the A1c’s percentage of hemoglobin that is glycated (and a goal of under 7%) to the self-monitoring of blood glucose they do at home… To reduce confusion, researchers have conducted a major international study to demonstrate how A1c correlates with self-monitoring.”

The ADA is clearly pushing hard for a massive migration to the eAG, which I find incredibly odd. They’ve even created little red handheld calculators (shown here) that they plan to sell to physicians off their website for easier conversion of A1c values into the “simpler” eAG. You can try their online calculator HERE.

One reason I find this so odd is that just last September, the Diabetes Care Coalition, a consortium backed by the ADA, JDRF and AADE, along with a half-dozen major pharma companies, launched a sweeping “Know Your A1C” public service campaign to get people aware of their A1c and what to do about it. I have to assume they’re just gaining traction with that campaign, so why “reinvent the wheel” by throwing an entirely new measure at an already struggling-to-understand audience?

When you dig a little deeper, you discover that the whole eAG initiative is less about reducing patient confusion and more about a good, old-fashioned standards war between competing associations and scientific factions, with the ADA on one side and the International Federation of Clinical Chemistry (IFCC) on the other — and PWDs caught in the middle.

It seems the IFCC was on its way to creating yet another average glucose measurement that the ADA disapproved of even more, so the organization is preempting that move by jumping on the eAG bandwagon. So much was acknowledged in a press briefing at the conference this weekend.

So whose standards will prevail? And where do we patients stand?

Of course it’s clear to me that far too many patients in this country don’t understand the A1c measurement (which btw is an average measured as a percentage of the amount of sugar attached to your hemoglobin molecules, which are present in your red blood cells). But I’d venture to state that the problem isn’t that the A1c result is expressed as a percentage, rather than a number that matches your home glucose meter (which lots of people don’t use or understand either).

The problem is that too many patients out there don’t even know there is such a thing as a three-month average glucose measurement or what it means to their health. THAT, my friends, is what matters. Why confuse the heck out folks by abandoning a measure that the D-world has known it for 25 years? In addition, so much effort has recently been made to promote the A1c, why kill it now? A nationwide switchover would no doubt be a very costly enterprise.

On top of all that, let’s look at the facts. We Americans do tend to cling to our traditional measurements, no matter how unclear they may seem. Come on, have we switched over to the metric system yet? Who cares that it’s much more logical and intuitive than feet and pints and ounces?

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Wednesday, June 11th, 2008 | Permalink | Comments (11)

Comments

I would think a linear relationship would only be accurate if the test subjects were wearing CGMs and the results compared to CGM output as calibrated by fingertip testing, since that would be the best way to reliably catch the postprandial peaks most likely to cause hemoglobin to become glycosylated…

One concern I have is the transition from the old test to the new test, because “…the new test results in a “normal range” for A1C that is 1.5 to 2% lower than the range everyone has become used to. For instance, what we call a 7% A1C would be reported as a 5% A1C with the new standard.” (http://americandiabetesnow.typepad.com/american_diabetes_associa/2008/06/a1c-eag.html)

This is likely to put a false sense of success and security on PWDs whose therapy is not bringing them within the standards of care — as well as an initial lassitude on the part of health care professionals who have not been clued into the new ranges, once their labs start coming back with the new numbers.
Posted by: tmana | June 11th, 2008 at 10:27 am
My doctors have always done this. “Your a1c is X, which is about equivalent to a blood glucose reading of Y.” That’s all they’re doing here, right? It’s just a change in the units, not a change in the chemistry of the test they’re running?
Posted by: mollyjade | June 11th, 2008 at 2:03 pm
Another case of too many geeks coming up with a perfectly viable and useful test, but then not having ANY understanding of how to interface with the end users.

It would be like saying, “wow, running that marathon took a long time, almost 408.7 dumbunits….” instead of saying 4 hours or whatever…Yes, we could measure time in dumbunits, and the ADA (American Dumbunit Association) could invent a nice little red calculator to convert dumbunits into hours and minutes…but what type of dingbat would even think of NOT using the standard measure…

Sorry, personal peeve, I have to deal every day with technically intelligent people who couldn’t scrap up an ounce of common sense to save their lives…

Thx,
Scott
Posted by: Scott | June 11th, 2008 at 4:36 pm
I think that many diabetics do not know what an hba1c actually is.
It is not the soluble sugar that is running around in our veins . It is the haemoglobin which has become glycated ie a sugar molecule has attached itself to a particular haemoglobin.We actually have various forms of haemoglobin for example hba1b, hba1a1 and hba1a2.
If a diabetic has an hba1c of 7% I think it means that 7 per cent of his hba1c has become glycated. I personally do not agree to give it the same value of glucose measurments (either mmol/l or mg/dl ) because we are basically measuring a different substance.
Posted by: simone | June 12th, 2008 at 3:45 am
If you can translate your A1C to the eAC how can it be more accurate?
Posted by: Russell Scott | June 12th, 2008 at 6:27 am
How much money has been spent on this so far and how much will be spent going forward? Also, how much of this money is actually our money (federal grant dollars, donations, etc…? And is this the best use of a finite resource - cash? I’m not saying yes or no to this since it’s just a number and an additional calculation (that we already deliver to patients as a mean blood glucose plus the A1c) so it’s not a big deal to change the math.

There should always be a business case made when something like this comes up and cost is a real consideration when there are so many other things we can spend money on to improve diabetes care.
Posted by: kevin | June 12th, 2008 at 10:04 am
Amy, thanks for posting this. I think people should also be aware that you can’t directly compare HbA1cs between people. Some people run higher or lower in their A1cs. I’ve been doing a number of researcher interviewers and a few have mentioned that two people with similar control can have A1cs that differ by as much as a full point.

This is why some people with A1cs of around 6.0 can have complications much soon than you would guess. They may simply be running higher than the A1c suggests. If we’re going to use A1c as a marker, I think it’s important to note that it may not translate to your average glucose very well.
Posted by: David Edelman | June 12th, 2008 at 10:13 am
Diabetes is all about change. You change your basals, your bolus, injection site, type of meds. Your numbers continually change, as do your emotions, hormones, stress, physical activity levels. The idea of changing from A1C to eAG shouldn’t be that hard to handle..and it’s about helping people relate the average 3 months numbers to something they understand (the numbers they hopefully see daily or multiple times daily).

Yes, the general public and uneducated PWDs may see this as another change, but that’s the glories of new research and our wonderful experts out there. Just think, over two decades ago insurance companies didn’t want to cover home BG meters because they didn’t think it was necessary (similar to the CGM reimbursement debate today). I think referencing the eAG will make PWD work harder to adjust their regimens so they will see results they understand immediately (not just “this A1C means you are at higher risk for complications”)
Posted by: DL | June 12th, 2008 at 10:43 am
I’ll bet there’s money, and lots of it, to be made in the switch.

Diabetes has to be one of TOP financial cows in all of medical-land. [I’m still trying to figure out shy insulin doesn’t have a generic by now. And don’t even get me started on sticks!] They’ve got us pegges as suckers because we are so desparate for better care. This may well be just one more gimmick.
Posted by: camille johnson | June 13th, 2008 at 10:49 am
I think the relationship between glucose tests and A1c tests is being turned on its head here. We don’t take an A1c test to figure out what our average glucose has been lately, any more than we climb on a bathroom scale to figure out what our average calorie intake has been.

The reason we care how sugary our blood has been lately is that sugary blood promotes glycation (bonding of sugar onto proteins), and glycation promotes degenerative disease.

What we really need to be concerned about is how much glycation has been going on in us lately, and the A1c test measures that directly, so A1c is the real measure of how we’re doing. Glucose monitoring is just a means to an end; it’s useful to the extent that it helps us in our effort to reduce glycation.

If we turn the thing around, and pretend that the A1c is just a means to an end, a tool for estimating average glucose, we’re confusing the issue (and distracting patients from what they should be focused on).

If a lot of patients don’t get what the A1c test is about, I doubt it’s because the subject hasn’t been sufficiently dumbed down for them. More likely it has been dumbed down too much. People who set out to dumb anything down never seem to end up making it clearer — they just make it seem vague, boring, and unimportant. Anyone taking an A1c test should be given a leaflet that explains what the test measures and why it’s an important thing to measure. It wouldn’t have to be a very long leaflet; the issue really isn’t all that complicated.
Posted by: Tom Ross | June 23rd, 2008 at 2:02 am
Hemoglobin A1C actually IS a change in the chemistry, both in the molecule being measured and in the method used to detect the molecule. Hemoglobin A1C, as some others have pointed out, is a measure of how much hemoglobin is glycated (the standardized term for glycosolated or glycolyzed). Glycated means that glucose has associated with some of the hemoglobin in your red blood cells. The more glucose you have in the liquid portion of your blood (called plasma), the more opportunity for your hemoglobin to become glycated.

All diabetics know that a high glucose level is bad for you. But, no matter how often you measure your glucose level throughout the day, you can not know how high or low your glucose actually was when you weren’t measuring it. Certainly, if you measure only your fasting glucose, you could get a very false sense of security. So, it may have been a little high in the morning—so what!! Here’s what—if it is high in the morning, it was likely very high at night (after you had that piece of pie when nobody was looking). If you are really good, you may even measure 2 or 3 times a day. You will likely still not catch your peak glucose level in one of those measures, so will not really know how well you are doing.

Well, maybe you say you know how you are doing because of how you feel, right? Actually, you will probably only know when you are at an extreme level, or when it is too late to correct a severe problem. One example of this is the nerve damage that is often associated with diabetes, called diabetic neuropathy. This can cause your feet to always feel like ice, no matter what you do, cause unhalting pain in the feet or hands, eventually numbness. This doesn’t sound so bad until you have to live with it day in and day out.

Then, along comes the hemogolobin A1C test. A1C is not cleared quickly from your blood stream like glucose can be. Once the hemoglobin is glycated, it will remain until after the blood cells die and even longer while the released hemoglobin is being cleared from your body. Because of this, the test is a better measure of glycemic control; i.e., whether your plasma glucose level is generally at a good level. This is overall what will determine the detrimental effects of glucose on your body, such as diabetic neuropathy. Your doctor may try to equate this to an average glucose level for you, just to help you understand what the test means. In those terms, A1C is a measure of how well you have controlled your glucose level over that past 3 months or so.

Does this mean you should stop monitoring your glucose and have just the A1C test done? Absolutely not. You still need to know what your glucose level is NOW in order to make adjustments NOW that can affect your A1C going forward.

How often you should have this test done depends upon how well you are currently controlled.
Posted by: JuST Jen | August 5th, 2008 at 1:11 pm