Gettysburg Medical News
The Clinical View
by P.E. Hoffsten, MD
29 August 2007

WHAT IS HEMOGLOBIN A1C?

            A gentleman recently came to the clinic to “check on his diabetes”.  He proudly brought a record of his blood sugars that he had checked at home and they were all looking very good.  I asked when he took his blood sugar to check and he said the first thing in the morning before he had eaten anything and consistently those sugars were between 90 and 110 milligrams % which is in the normal range.  I asked if he had checked blood sugars later in the day after he had eaten and he said “a few times”.  Specifically, he checked when he thought that his blood sugar might be low.  Specifically, sometimes he felt weak and thought he needed to get something to eat.  But he acknowledged that he never really found his blood sugar under 200 milligrams % when he checked it later in the day even when he thought it would be low.  Two hundred milligrams % is distinctly high. 

            So I told him we would check his hemoglobin A1C to see how well his sugars are really being controlled.  The value came back at 8.9%, distinctly high.  A normal hemoglobin A1C blood test has the value of 6% or less, preferably 5.5%.  I told him that his blood sugars really weren’t controlled at all and there needed to be additional steps taken to better control his diabetes.

            His next question was “What is hemoglobin A1C?”  Without getting into a complicated scientific explanation, hemoglobin A1C (also called glycosylated hemoglobin)is a component in the blood that results from the chemical reaction between glucose and hemoglobin in the red blood cells.  Glucose is another word for blood sugar.  Hemoglobin is the protein in the red blood cells that makes blood red.  Glucose and hemoglobin will react with each other at a rate that is primarily dependent upon the glucose concentration in the blood.  The higher the blood glucose, the more hemoglobin A1C there is.  Therefore, the higher the hemoglobin A1C level, the less control the person’s diabetes is. 

            The beauty of this test is that it can be run every three months and tell us what the average blood sugar has been for the past three months.  Once the hemoglobin A1C is formed from glucose and hemoglobin, it remains in the blood for about three months before it is digested and metabolized away.  Thus it gives us a good indication of how well the person’s blood sugar has been controlled for the last three months. 

            Doctors had suspected for many years that the higher the blood sugar, the more likely the person was to have diabetic complications.  But that was not proven until the 1990’s.  These diabetic complications come in two forms.  The first form was what are called microvascular complications. They involve degeneration of tiny blood vessels all over the body.  But most effected by the high blood sugar are the tiny blood vessels in the eyes, the kidneys, and the nerves.  When blood sugar remains too high too long, the person goes blind, develops kidney failure requiring artificial kidney treatments, or develops numbness and pain in their feet which is the reason that so many diabetes have their feet amputated.  These are the very bad complications that diabetics hate.  Once they begin to occur, they are very unforgiving and starting to control blood sugars then does not reverse the damage already done.

            The other kind of blood vessel damage done by diabetes is called macrovascular disease and involves the heart attacks and strokes that diabetics get much more commonly than the general population.  These complications are  related to very high blood sugars but also multiple other problems that diabetics tend to have including high blood pressure and high blood cholesterol.

            The gentleman mentioned above then asked what he needed to do to get his blood sugar better controlled.  He was substantially overweight, really did not control his diet at all, and absolutely promised that he would never take insulin.  He said that he just couldn’t imagine sticking needles into himself to inject insulin and he wasn’t going to do.  So I told him that there were various medications that might be used to help get his diabetic condition better controlled.  The cheapest medications are called glucotrol, glyburide, and metformin.  Each of these medications can be obtained for about $4.00 a month from many pharmacies.  Very frequently, these medications are not enough to control a person’s diabetes and they have to have an additional medication called Actos that is very expensive.  A new medication called sitagliptin (Januvia) has promised a side effect free medication to help control diabetes but it is somewhat expensive also.  As a general rule, oral medications to treat diabetes are more expensive than using insulin.  But the least expensive way of all and the most effective is to modify a person’s diet and exercise program to control weight and blood sugars. 

            At this point the gentleman said he didn’t want more medicine and he was not going to take insulin.  Instead, he said he “wanted to try diet and exercise” to better control his diabetes.  I told him that trying is ”a command to fail”.   Either do it or do not do it.  But please do not tell me he “wants to try”.  That is a double cop-out.  Neither “wanting” nor “trying” is doing.

            The target marks for hemoglobin A1C are 7% or less, preferably 6% or less.  Generally, when hemoglobin A1C is no higher than that, diabetic complications are progressing very slowly if at all.  Between 7 and 8% complications will be expected to progress over 5-10 years.  When the hemoglobin A1C is above 8%, complications are occurring at a relatively rapid rate and microvascular complications of kidney disease, eye disease, and nerve problems in the feet will tend to develop within several years.  As I mentioned above, once these complications occur, it is too late to begin to control the diabetes and expect the problem to go away.  The answer for any diabetic is to check the hemoglobin A1C every three months and make sure that it stays below 7%, preferably below 6%.  When this is done, diabetic complications can be relatively well assured not to be progressing.

            As a final note, I suggested to the gentleman above that he check his blood sugars two hours after a meal randomly.  Finding that he had a normal blood sugar every morning was falsely reassuring him that his blood sugars were very well controlled.  Checking two hours after breakfast one day or two hours after lunch, or two hours after supper are the right times to check blood sugars to find out whether or not the sugar is really being controlled or not.  Granted that doing this can lead to some horrible disappointments on how easy it is to run a person’s blood sugar way up but that is the burden of diabetes.  The alternative is to sit and wonder what happened to the persons feet, why they can’t see,  why they need “kidney treatments.

This and other columns available at www.macpierre.com.