Discrepancies between A1c and The Meter

I would like to know if anyone has had large discrepancies between their A1c value and the meter readings or averages, and which read higher.

My a1c tends to come in lower than my meter average. A1cs don’t directly relate to our meter readings - They’re a whole different bunch-o-numbers (but similar enough for us using mmol to get a rough idea). Depending on where you get it done you may see different numbers too.

The difference can be quite big because the meter only averages the times you chose to test, where an a1c doesn’t hide much at all.

Have you had an a1c that doesn’t seem right? Mistakes do happen, it could be they’ve got you wrong… or it could be that you’re missing your own highs or lows at times when you don’t test.

Check out this chart for a good idea of how your a1c equates to your true BG averages. Warning, it’s depressing :stuck_out_tongue:

My A1C was phenomenal, It was 6. But my numbers had been creeping up and staying in the upper 200’s and 300’s. I was 270 when I went in, and my endo adjusted my insulin. My meter averages were all mid 250s. I was scared to death to see my a1c result. While pleasantly surprised, I’m totally pissed off at my meter for all the worry it’s caused. I’m always really careful to have clean hands, I have no strips that have expired, and I always calibrate the meter, so I just can’t figure it. My meter read 266, compared to the 270 at the docs office. I’m not sure what to trust, and these are the devices we use to adjust the insulin doses daily. It’s kind of scary.

I just recently experienced a similar quirk. I was feeling very smug about being able to really closely predict my AlC based on my meter average. Like, if the average (consisting of 3 pre and post prandials, one bedtime and one 2 am reading) was less than 150, then my AlC would be just around 7, give or take.
3 months ago, I had been coming off a terrible period of poor control, mostly hovering around 210-230. I was sure I’d be somewhere in the low 9’s, but came in at 7.5. Say what?
I was really ticked off at this - everything with db is unpredictable, and now we’ve got yet another that is.

If you are anemic, your A1c can be MUCH lower than your actual average blood sugar has been over the period.

Also, some people have strange genetic forms of hemoglobin and their A1cs aren’t accurate.

If you think there is a huge gap between your readings and your A1c, and you are testing a lot the readings are probably accurate. You can also ask for a Fructosamine test. If you are anemic, or have the strange hemoglobin, it will give an accurate average value.

Is that true? I’m historical on having bouts of anemia. Usually coming from my practically vegan diet. Always low in B12. Used to get shots for it. Not so much iron deficient I think or does it matter? Thanx for your your response!!! I’m usually pretty logical so that has been driving me absolutely nuts. It’s hard to trust your monitor when you’d rather believe the A1c. I’ll have to ask my endo to check before my next test in September.

My A1c is almost always 0.5 higher than what it “should” be based on my meter average. I figure I’m missing highs between tests, but the good thing is that it’s almost always 0.5 so it’s still easy to accurately preduct what my A1c will be.

I had an A1C done yesterday and it was 6.3. I never see numbers over 120 so it should have been much lower. I’ve only had a couple of A1Cs in the 5s even though my BG is always between 80 and 120. It doesn’t make sense. My endo doesn’t know why but agrees that it should be lower. I am not missing highs, I test frequently. She did give me a free-style meter and a couple of my tests were higher than with my One Touch, but not by much and my fasting this AM was exactly the same with both meters.

I had the same problem for the first 1.5 year of pumping! My a1c was always between 7.5 and 7.8 meanwhile my meter averages were always in the 130’s and 140’s. My CDE and I thought it could’ve been my overnight readings (when I wasn’t testing) but when I did use the CGM for a period of couple of weeks my overnights were fine. Finally this past June my a1c was 6.4. I could not have been happier however I’m a little curious as to what made it go down so drastically since I hadn’t really been doing anything differently. A1c results are based on the assumption that everyone’s red blood cells live for 90 days … I think it’s possible that some could live longer or shorter. I read somewhere also that there are certain things that could have an effect on results like anemia. “If you have an abnormal type of hemoglobin, such as sickle cell hemoglobin, you may have a decreased amount of hemoglobin A. This will affect the amount of glucose that can bind to your hemoglobin and may limit the usefulness of the A1c test in monitoring your diabetes. If you have hemolysis or heavy bleeding, your test results may be falsely low. If you are iron deficient, you may have an increased A1c measurement.” (found at labtestonline.org) or “Laboratory results may differ depending on the analytical technique, the age of the subject, and biological variation among individuals. Two individuals with the same average blood sugar can have A1C values that differ by as much as 1 percentage point. In general, the reference range (that found in healthy persons), is about 4%–5.9%. Higher levels of HbA1c are found in people with persistently elevated blood sugar, as in diabetes mellitus. While diabetic patient treatment goals vary, many include a target range of HbA1c values. A diabetic person with good glucose control has a HbA1c level that is close to or within the reference range. The International Diabetes Federation and American College of Endocrinology recommend HbA1c values below 6.5%, while American Diabetes Association recommends that the HbA1c be below 7.0% for most patients. A high HbA1c represents poor glucose control. Persistent elevations in blood sugar (and therefore HbA1c) increase the risk for the long-term vascular complications of diabetes such as coronary disease, heart attack, stroke, heart failure, kidney failure, blindness, erectile dysfunction, neuropathy (loss of sensation, especially in the feet), gangrene, and gastroparesis (slowed emptying of the stomach). Poor blood glucose control also increases the risk of short-term complications of surgery such as poor wound healing. Lower than expected levels of HbA1c can be seen in people with shortened red blood cell life span, such as with glucose-6-phosphate dehydrogenase deficiency, sickle-cell disease, or any other condition causing premature red blood cell death. Conversely, higher than expected levels can be seen in people with a longer red blood cell life span, such as with Vitamin B12 or folate deficiency. The approximate mapping between HbA1c values and average blood glucose measurements over the previous 4-12 weeks is shown in the table.” (found from wikipedia.org)
I hope this all makes some sense!