Inter-individual variation in red blood cell lifespan significantly influences HbA1c values, which may lead to inaccuracies in the estimation of average blood glucose levels when an individual's red blood cell lifespan deviates from the population mean.

Study: Estimation of HbA1c Levels in Transfusion-Dependent Thalassemia Patients in Comparison With Normal Healthy Individuals

The study shows that people with a blood disorder that affects red blood cell life have misleadingly high HbA1c levels, even when their blood sugar is normal, which supports the idea that red blood cell lifespan can throw off HbA1c readings.

Study: Rectify the impact of shorter red blood cell lifespan upon HbA1c detection values in T2DM patients: modeling and internal-external verification

The study found that people with shorter-lived red blood cells have lower HbA1c levels even if their blood sugar is high, which can be misleading—just like the claim says.

Study: Accurate prediction of HbA1c by continuous glucose monitoring using a kinetic model with patient-specific parameters for red blood cell lifespan and glucose uptake

The study shows that when doctors account for how long a person’s red blood cells live, they can predict their HbA1c more accurately, which means red blood cell lifespan really does affect HbA1c results.