These posttranslational modifications of the HbA molecule
to form GHb are essentially irreversible, and glycation
of hemoglobin occurs over the entire lifespan of the
erythrocyte; the level of GHb is an integrated measure
of the average blood glucose during these 120 days.19–23
The question is, how accurate can this be? If the lifespan
of the erythrocytes is normal, then the percentage
of GHb is a reliable indicator for the glycemic state
of a patient during the past 2–3 months, but not if the
lifespan is reduced. Within these 120 days, recent
glycemia has the largest influence on the HbA1c value.
Theoretical models and clinical studies suggest that,
in a patient in stable control, half of its HbA1c levels will
be formed in the current month before the test, 25% in
the month before that, and the remaining 25% in the