After 11 years with an HbA1c around 6.0 that was refractory to everything I tried, I have finally been able to improve my glucose regulation. However, even though my glucose regulation improved—as measured by fasting glucose and fructosamine—this progress was masked by an HbA1c that remained elevated.
That discrepancy between the inflated HbA1c and actual glucose levels is known as the glycation gap.
The mechanism is simple: HbA1c measures the glycation of hemoglobin in red blood cells (RBCs) and depends on both average glucose levels and the average age of your RBCs. Older RBCs result in a higher HbA1c, even at identical glucose levels.
In my case nothing moved the glucose (fasting glucose around 100 and fructosamine over 285 which is the abnormal threshold).
I was on 25mg Empagliflozin and 100mg Acarbose since the end of 2023 and my FBG did not move at all.
I tried Metformin on and off during that period with no effect either.
Then in January I started Imeglimin (1g BID first then 1g TID) and after a few months my Fasting glucose dropped to 90 and my fructosamine to around 240 which is normal blood glucose.
The problem was that the HbA1c would not move and remained around 6.0.
After digging down the rabbit hole with the various versions of Claude it appeared that my iron was declining and entering the iron deficiency without anemia zone.
That low iron reduced the capacity for creating new RBCs. Consequently, with fewer young and more old RBCs, the average age of the RBCs increased, which inflated the HbA1c value and created that glycation gap.
The solution was as simple as supplementing with iron glycinate and in 3 weeks, the HbA1c dropped from the overestimated 6.0 to 5.6 which is now consistent with the FBG and fructosamine levels.
Interestingly I already had a drop of HbA1c to 5.6 when I took rHGH for 10 weeks at the beginning of 2025. At that time my glucose regulation was still bad so this was a glycation gap in the opposite direction caused by the rHGH increasing the production of new RBCs.
Here are some plots showing this.
A note about the recent FBG spikes on the plot. It’s blood draws taken at various times after my rapamycin dose to evaluate the impact on my blood glucose and other biomarkers. (bad obviously)
I do daily fingerpicks FBG measurements and outside 1 week or so after the rapa doses (8/2/2mg) it’s back to 90.
