Tuesday, April 12, 2016
HbA1c RESULTS CALLED INTO QUESTION.
IS THE HbA1c TEST A RELIABLE INDICATOR OF AVERAGE BLOOD GLUCOSE OVER THE PAST THREE MONTHS?
If you read my summary post from twelve days ago, you saw the picture I took of my test results from my home HbA1c test. Watching what I ate and fasting a HECK of a lot of days in the first three months of the year, I still got a reading of 5.2%, which is equivalent to an average blood glucose of 103 mg/dl.
I was so upset when I saw that number! How could it be true? The answer is, it couldn't be true.
I went to the interwebs to check on the reliablility of this test and found several articles that showed that the results are skewed, either higher or lower, based on the patient's history of anemia and/or iron deficiency.
I have had anemia and/or iron deficiency since childhood. Even now, when blood tests are done, I am lacking in red blood cells. Sometimes I take a supplement and that helps, and sometimes I just don't worry about it.
The article that I felt was the most clear was this one written by Dr. Chris Kesser. In the article, he says this:
"Sugar has a tendency to stick to stuff. Anyone that has cooked with sugar can tell you that. In our bodies, sugar also sticks – especially to proteins. The theory behind the A1c test is that our red blood cells live an average of three months, so if we measure the amount of sugar stuck to these cells (which is what the hemoglobin A1c test does), it will give us an idea of how much sugar has been in the blood over the previous three months. The number reported in the A1c test result (i.e. 5.2) indicates the percentage of hemoglobin that has become glycated (stuck to sugar)."
However, people with low red blood cells get inaccurate results. He continues:
"This confused me early in my practice. I was testing blood sugar in three different ways for all new patients: fasting blood glucose, post-meal blood sugar (with a glucometer) and A1c. And I was surprised to see people with completely normal fasting and post-meal blood sugars, and A1c levels of >5.4%."
You can read the rest of Dr. Kesser's article to learn how he changed his procedures and no longer uses the HbA1c as the determining factor when he checks the progress of his patients. For myself, I decided to check my blood glucose nine times per day over a one week time frame to see if it was true that my BG was rising so high after eating as to cause me to have an average blood glucose of 103 mg/dl, or 5.2%.
I tested my blood glucose right before each of my three daily meals. I also tested one hour after beginning each meal, and again two hours after beginning each meal. Of the seven days, I fasted only twice, from dinner one day until breakfast two days later, which made the duration of those two fasts 36 hours each. On the first day that I fasted, I did check my BG nine times. The second day that I fasted, I only checked it twice, because I could see from the last fasting day that there is barely any fluctuation when you are not eating at all. On that second fasting day, I filled in estimates of what I considered to be reasonable numbers.
Here is a chart (click to enlarge it if necessary) that shows my results for this past week:
My TRUE average blood glucose over these 63 readings was 80 mg/dl or 4.4%. And this is with me eating the same way that I was during my challenge, and even with me only fasting twice that week, when I was fasting three, four, or five times per week in the last half of the challenge, which would probably mean that my HbA1c should have been even lower than 4.4%.
My highest reading was 98 mg/dl or 5.0% (two hours after eating a meal) and my lowest reading was 68 mg/dl or 4.0% (the morning after a 36-hour fast).
My conclusion is that, had the HbA1c test been accurate, I would have gotten a reading somewhere in the neighborhood of 4.4%, not 5.2%.
Now that I have proved this to myself, I am going to go back to not checking my blood glucose as often. I will check it now and then, and possibly when I eat a food I am not sure of to see if I can tolerate it.
In one of the diabetes Facebook groups that I belonged to last summer, I mentioned that I did not often check my BG. The other diabetics were outraged and told me I had to test nine times per day or more every day for the rest of my life! When I explained that I am perfectly controlled with diet and that I am on no diabetic drugs or insulin, they didn't care. They felt that I was taking my disease lightly and it was an insult to all the diabetics that test multiple times per day. They threatened me with blindness, nerve damage and amputations if I did not test every day.
At one point, I had made the mistake of saying that it was too expensive to do all that testing. That's when the you-know-what really hit the fan! They wondered what I cared most about, my disease or my money.
Well, since my diabetes is perfectly controlled with diet (and exercise), I care about the money. If it ever becomes evident that I am no longer controlled, then I will spend the money. For now, I will use that money to buy a nice steak!
Keep an eye out for my next personal challenge, which will center around body composition.
Onward and Downward!