Why A1c can be different from eA1c and GMI



How about if someone has Thalassemia, an inherited blood disorder where red blood cells are smaller than normal and can cause severe anemia? Would that also cause an a1c discrepancy - increase or decrease?


Thalassemia shortens RBC lifespan, so it would reduce A1C.


Ah, thank you! Maybe that is why I can achieve an a1c of 4.9 :frowning:

Confusing because my lab a1c is consistently higher by 0.3 than my a1c as calculated by xDrip+ / Dexcom which just uses the CGM BG avg values, not the actual glycosylated hemoglobin as in the lab test:

“A1c:” + (Math.round(10 * (avg + 46.7) / 28.7) / 10d) + “%”;


I think the CGM estimates are not very reliable for many people.


True, that is the case for me for some percentage of the time, for sure. :frowning:


I am sure the numbers would not change significantly. If you are achieving a 4.9 with RBC’s that live only 10 weeks, it would certainly not jump up to anything horrible if they lived 15 weeks. The 4.9 is a reflection of your good control.

Also, since you run a lot, your hematocrit and hemoglobin may be lower than normal, because running has increased your blood plasma volume.

Don’t worry too much if you see lower numbers there. I think you are in great shape. Keep doing what you are doing.


Yes, they usually are, too!

Thank you, I appreciate this!! :sunny:


Google “Runner’s Anemia”. Take it as a sign that you are kickin’ it.

Also, check out your blood counts and your A1C after a hard training period, about 10-14 days after a race. See how it drops. That is a badge of honor. Wear it proudly.


Oh, wow, I hadn’t heard of that before. Next endo appt is April but hope to have annual physical in Mar! I’ll aim for that time frame to see how the CBC looks!


I found this googling Runner’s Anemia …

One effect of regular endurance exercise is that it produces an increase in red blood cell mass and plasma volume

I didn’t realize this… No wonder I feel so much better w/ nice, long runs.


I think one of the other effects of thalassemia is that your body will counter the misshaped RBC’s by creating more of them.

As discussed earlier in this thread, possibly this could lower A1C, at least in theory.

Have you been checked for thalassemia?


Yes, I learned I had it when I was young. Initially thought to be just anemia but further tests showed it was thalassemia minor.