So, Samson had his 3-month endo appt yesterday – the first since he was admitted to the hospital in November for his seizures.
I was dreading his A1C – he’s been running about 10 points higher on his estimated average glucose. His A1C has been at 6.5 for more than a year. His eAG is almost always around 130 mg/DL,this time it was 142 mg/DL. So he has always, in the past, run a much higher A1C than his eAG would suggest.
Anyways, this time his A1C was… 6.2???
I am not sure what to make of this. He spent a lot less time in the low, critical low range, which is great! But he also spent double the time in the super high range above 250 mg/DL.
I’m trying to figure out what could account for the difference and there are a couple of possibilities. One is that this is the first 3 months that he’s been using the G6 consistently, rather than the G5. So it’s possible the G5 was always running about 10 or 20 points lower than his true BG, even with calibrations.
Another possibility (a sort of depressing one), is that they took lots and lots and lots of blood from him during the week he was in the hospital – which also would have been the oldest red blood cells in the sample. He got a bit anemic while he was in the hospital from all the blood they took. I guess that would mean his A1C only reflects about 2 months or 2.5 months of RBCs’ glycosylation?
Anyways, I’m curious if folks have other ideas. For those who have switched from G5 to G6, have you noticed any differences in how your numbers correspond to your A1C?
Overall, I’m not too hung up on the A1C because my day-to-day task is going to be the same; just try to spend as much time as is realistic in range, try to reduce those lows and try to minimize highs. But it is somewhat baffling and I’d be curious what I should expect in another 3 months if I’ve not been able to get Samson’s BG down.
Yes, the downside of A1C is that it’s influenced on RBC lifespan. So anything that changes the lifespan will affect the number.
But there is no reason to be upset. A 6.2 is better than a 6.5. Even if it was influenced by the average RBC lifespan being shorter this time, maybe that would make the 6.2 more like a 6.5 on any other test. But still it sounds good.
The thing to be conscious of is if there is a severe issue that is shortening RBC lifespan. Things like an infection, kidney or liver problems, anemia, sickle cell disease, or other illnesses. If you are not having other health issues beside the seizures, and if doctors tell you the seizures are not affecting his RBC lifespan, and those other types of things can be ruled out, then that A1C seems like a good report.
A general blood panel on his normal physical can help to rule a lot of those issues out.
I had my A1c done 1 month after switching to the G6, and it was the same as the prior A1c (while using the G5). However,
This was not my experience with the G5. Sometimes the G5 was higher than my bg, and sometimes it was lower. Generally, the G5 followed my bg levels better than others on here report. The G6 seems to be a little bit better than the G5. However, I did replace my last G6 after a sensor restart because it was having trouble maintaining a calibration properly (it’d be off about 12 hours after I calibrated it). So the G6 isn’t always perfect.
Anyway, my A1c is always lower than my eAG by .5%- .8%. I’ve asked my doctor about it at the last two appointments. He agreed to run some extra tests at my last appointment, but he didn’t think I should be concerned. He said that it’s usually more obvious when someone has a discrepancy that’s attributable to a different medical condition. All my tests came back normal. Samson’s anemia could possibly be the reason, but hopefully that’s now resolved. It seems reasonable that his A1c will be more in line with the eAG at his next appointment.
@TiaG, us it possible his last 30 days were a lot better in control?
Don’t know if you remember these couple threads that happened a few weeks ago, when someone was arguing false interpretations of A1c articles because they were misunderstanding the arguments. In one of them, there was good mathematical modeling of A1c that showed the last 30 days of the A1c measurement to be much more significant in the overall A1c:
I also ran around the same time into an article that argued with good math that each person has a different average half life for red blood cells, and that it should be taken into account for A1c measurements. The differences were quite significant.
As for us, we tend to trust GMI more than A1c. But this is not a good thing in your case
Well, his blood sugar is about 8 points lower in the last 30 days than it was in the 30 days prior, and about 12 points lower than the overall average for the 3 month period. So yes, his average BG has been going down down down for the past few months. It was in the 160s and 170s while he was in the hospital and has been just arcing downward.
6.2 and 6.5, in the context of what we are talking about here, is essentially exactly the same number.
It is not biochemically accurate that an exact average blood glucose level should produce an exact A1C—- that’s not really how it works… those correlations are just loose approximations
If all of a sudden his A1C was 4.2 or 9.2 we’d have a mystery on our hands… but this is nothing to worry about or even overthink
@TiaG, I have a feeling you are right. Most of the time we have been surprised by an A1c we have been able to attribute the discrepancy to the variation across the 90 days, giving a preponderance to the later part of the cycle.
There are still a couple of unexplained numbers for which I suppose it is just measurement noise
Yes, this is true.
But I think the point is not that there’s a difference in A1C from one time period to the next, but that the direction of error has switched. Also, we have a persistent pattern that’s been consistent, using the same lab equipment, over the course of more than a year. Samson has had maybe six or seven A1Cs of 6.5, and his eAG for all those times has basically been the same or lower. I don’t think there’s been any point since his diagnosis onward that his eAG predicted an A1C higher than the lab test showed. So whatever the error, whatever the natural variation of the lab test, it does seem to me that something has changed in his biology. It’s possible it’s just an outlier measurement or a miscalibrated machine or just natural variation, but I don’t know that that’s the most logical explanation.
Congratulations on the great A1C! All we can do is exactly what you stated in your very last paragraph “try to reduce those lows and try to minimize highs”, and let the cards fall where they may.
This may have contributed. During chemo, my a1c was done about half way through. My rbc and platelets dropped quite a bit, and over time didn’t bounce back by next chemo. I had a routine appt with endo, and a1c was 4.6, rather than 5.4-5.8 that had been average. Only 4.x I’ve ever had!!
