A1C

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What does the A1C Measure?

When you get an A1C test, you are, of course, checking your blood. That is

the simplistic answer. It is, however, a lot more than that.

The A1C is the new standard name for blood level tests that have variously

been called glycated hemoglobin, glycohemoglobin, glycosylated hemoglobin,

HbA1c.

It describes a series of stable minor hemoglobin components formed slowly

and nonenzymatically from hemoglobin and glucose.

The rate of formation of these hemoglobin components is directly

proportional to the glucose level. Your A1C level provides you with your

glycemic history

of the previous 120 days, since that is the average life span of your red

blood cells.

The A1C " most accurately reflects the previous 2-3 months of glycemic

control, " according to the American Diabetes Association's

Position Statement on Tests of Glycemia in Diabetes.

That's the establishment position. But even this careful statement is

subject to some caveats.

The A1C reflects the last four months, says Dr. Goldstein, a pediatric

endocrinologist practicing in Columbia, Missouri, and the previous chair of

the National Glycohemoglobin Standardization Program. " But it reflects the

last month much stronger than four months ago. It is a weighted average.

About

half of what goes into the glycohemoglobin is the past month or so. "

Ron Sebol,

a retired electronics engineer living near Columbia, land, says,

however, that the A1C measures an even shorter period. A standard text,

Ellenberg &

Rifkin's Diabetes Mellitus, bases the chapter on the kinetics of glycation

on differential equations that were computer modeled and presented a graph

of

a square wave response. Ron emphasizes that the equations and the computer

model were validated in a test conducted in a hospital setting and are

therefore

beyond mere conjecture.

" That is how A1C reflects a stepwise abrupt change in average blood

glucose, " he writes me " To an electronics engineer, but not the doctors who

wrote the

paper, the graph was instantly recognizable as an exponential of the same

sort as describes charging a capacitor via a series resistor. "

This means, he says, that in only one week the A1C has changed more than 50

percent. By the 47th day it has changed 99 percent.

There is less dispute over how often we should get our A1C checked. If you

are meeting your treatment goals and have stable control you should be

tested

twice a year, the ADA says. When you are not meeting your goals or you

change your therapy, you should test four times a year.

Your goal should be an A1C of less than 7.0 percent, the ADA says. Many

people believe that this level is too high. The Diabetes Control and

Complications

Trial (DCCT) showed that near normalization of glycemic levels prevent

complications. That trial set an A1C level of 4.0 percent to 6.0 percent as

normal.

The United Kingdom Prospective Diabetes Study (UKPDS), the other major

diabetes study, set the normal level as less than 6.2 percent.

Dr. K. Bernstein, an endocrinologist in practice in Mamaroneck, New

York, and author of

Dr. Bernstein's Diabetes Solution,

is perhaps the sharpest critic of the ADA's treatment goals.

" I feel diabetics are entitled to the same blood sugars as non-diabetics, "

he wrote me recently. " This means that an appropriate A1C would be in the

vicinity

of 4.5%.This numbers happens to be the value for blood sugar that I've seen

over and over on the non-diabetic meter salesmen that visit my office. It

also

happens to be the value of my own A1C. Since an A1C of 6% corresponds to an

average blood sugar that is more than 50% above normal, it certainly does

not

meet the guidelines for good health and longevity. "

Many people question Dr. Bernstein's goals. That includes two contributers

to this article, Ron Sebol and Dr. Little.

" The DCCT data stand as a contradiction, " Ron writes. " I posted some

calculations based on the DCCT and in them found that a person with an A1C

of 6 had

a 98.5% chance of being complication free over a 15 year term. The dramatic

shift in eating life style that Bernstein requires has virtually no payoff

in risk reduction since going from 1.8% risk to zero is not worth the price

in life style. Add to that that with strategic use of supplements known to

be able to reverse glycation damage, and you have essentially a zero risk of

complications with a diet much more mainstream than Bernstein insists is

needed.

Alpha lipoic acid, acetyl-L-carnitine, benfotiamine, and pycnogenol can, I

am convinced, make an A1c of six or even 6.5, entirely safe. What cures also

prevents. It is the difference between having to limit to Bernstein's 12

grams of carb per meal vs. limiting to 50 that is at issue. "

There is too much risk for hypoglycemia with the level that Dr. Bernstein

recommends, Dr. Little believes. " Certainly a normal range goal would be

appropriate

for some people with diabetes but not all. One has to weigh the risks and

benefits and there are certainly risks of a person with diabetes having too

low

an A1C. A person without diabetes and one with diabetes may have the same

A1C but their blood glucose swings would be different; the person with

diabetes

would be a much higher risk of hypoglycemia. "

The period that the A1C measures and how low it should be remain in dispute.

What remains clear, however, is that it is the key test in our arsenal of

weapons

in our fight for control of diabetes.

rm

This article originally appeared on mendosa.com, October 28, 2003.

Last modified: October 29, 2003