I didn’t read the original article, but the length of time a red blood cell lives definitely impacts HbA1c level. HbA1c simply measures what percent of red blood cells have been glycated. This tends to happen more frequently when BG is elevated, so there’s a very loose correlation that as BG goes up, so does HbA1c. But also, the longer any given red blood cell lives, the more opportunity it has to become glycated, regardless of average BG. When you give blood, you force your body to make new red blood cells, which simply haven’t had time to become glycated, hence the artificial lowering of HbA1c.
I have the opposite problem. My HbA1c is always insanely higher than my starts CGM stats. Maybe I should start giving blood! (I thought we weren’t allowed to???) Like, as much as 2% higher. It’s really gutting to go in to an appointment with 98% TIR and an estimated A1c in the 5s, only get blood work back that shows in the 7s. What’s even the point if I’m going to “fail” anyways when doing so well??? (Yes, i make sure my sensors are accurate. It’s not a data problem. It’s a me and the test problem.) So I’ve long been on a research mission to understand WHY. And more importantly, does it even matter what the A1c says if I’m taking excellent care of myself? My doctor and I have pretty much decided to ignore the bloodwork and go by the sensor data. I haven’t even done a HbA1c test in more than a year, maybe 2 I’d have to look it up, she just reports the Dexcom stat.
What I’ve learned is that the HbA1c test is absolute crap and really doesn’t tell us anything. It’s all we had for many decades and it was better than nothing, but it’s not what we’ve been lead to believe it is. There’s no mythical line in the sand where if your blood sugars look like this, then your HgA1c will look like this. You also can’t infer management from A1c alone, like we’ve been lead to believe. When you take a group of people and plot their average BG against their HbA1c, it’s a massive shotgun scatterplot of data. Dots all over the place They don’t all sit in a pretty row. If HgA1c is the only thing you look at, there are people who desperately need help that aren’t getting it because it’s not reflected in their A1c, and like me, there are people rocking it yet are failing to meet the recommended standards.
One such example:
There are so many things that skew HbA1c results. I learned that my living at high elevation is one of them. Iron levels impact HbA1c. Underlying health conditions that affect red blood cell longevity affect HbA1c. Even exercise affects red blood cell lifespan. Even your genetics skew HbA1c.
The thing I’ve not been able to figure out is if HbA1c even matters. It’s the metric all diabetes health studies are based on, because it’s all we had for so long. But I’ve never been able to find a study that specifically looks at the variances between measured HbA1c and TIR/average blood sugar/standard deviation, and how that affects outcomes. Am I just destined to have high BG complications even though I’m doing great? Or am I likely to circumvent them like others with similar CGM data? I’m 35 years since diagnosis. My management was really crappy the first 25 years, but I’ve been trying really hard the last 10. I did develope some diabetic retinopathy that’s been treated and resolved, but no other complications thus far. Fingers crossed.
