Your HbA1c number isn't just about your average blood sugar — it also depends on how long your red blood cells live. The longer they stick around, the more sugar builds up on them, which can raise your HbA1c even if your blood sugar is stable.
Evidence from Studies
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The study shows that people with shorter-lived red blood cells have lower HbA1c readings than expected, meaning HbA1c isn't just about blood sugar—it also depends on how long red blood cells live.
The study shows that how long your red blood cells live affects your HbA1c level, because longer-lived cells have more time to build up sugar. This supports the idea that HbA1c isn’t just about average blood sugar.
Glycated hemoglobin and red blood cell indices in non-diabetic pregnant women
The study shows that HbA1c levels are linked to red blood cell traits, which suggests that how long red blood cells live can affect HbA1c, not just blood sugar levels.
The study looked at a marker of red blood cell age and found it didn’t always match up with HbA1c, but that’s likely because the marker itself can be misleading after puberty — not because red blood cell lifespan doesn’t affect HbA1c.
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