First, folks with healthy blood sugar levels may have longer-lived red blood cells than those with poor glucose regulation.
The better you regulate and manage glucose, the longer your red blood cells can survive. The longer your red blood cells live, the higher your circulating hemoglobin. And if circulating hemoglobin is high, that will probably show up in the A1c blood panel.
In other words, it’s possible for your hemoglobin A1c to appear a bit high, even — or maybe especially — if your blood sugar regulation is excellent.
And the opposite can also be true.
Poor glycemic control may kill off red blood cells prematurely. This can result in less circulating hemoglobin and a lower hemoglobin A1c measurement — even if your actual glucose levels are actually on the higher side. How ironic!
If you’re feeling confused, no wonder. This is one of those situations where being especially healthy can actually interfere with accurate assessment. It’s also why scientists are looking for better tests.
How long do your red blood cells live?
If longer-lived red blood cells can lead to higher hemoglobin A1c levels, despite healthy glucose levels, maybe doctors should be evaluating the lifespan and turnover of red blood cells in their patients.
Here’s a calculation for doing that. It’s just an estimation, as blood chemistry calculations aren’t perfect. Still, it may give a bit of insight into your personal red blood cell lifespan and it offers food for thought.
To do this calculation, you’ll need to know your reticulocyte count and your hematocrit.
Reticulocytes are early red blood cells. Produced in the bone marrow, they’re released into circulation as reticulocytes, and in a few days transform into fully mature red blood cells.
Reticulocytes can be used as a marker of red blood cell production.
For example, in someone who is losing blood (for example, from a bleeding ulcer or heavy menstruation) or in someone with short-lived red blood cells, the reticulocyte count may be higher. This is because the body will attempt to increase blood cell production to make up for the loss.
On the other hand, a low reticulocyte count can indicate that the body is generally happy with the amount of red blood cells or their lifespan, and doesn’t need to pump out as many reticulocytes.
The equation for determining how long your red blood cells are surviving is:
Red blood cell survival (days) = 100/[reticulocytes (percent)/reticulocyte life span (days)]
Here is an example:
Let’s say your reticulocyte count is 0.8% and your hematocrit is 45. Pulling from corrected reticulocyte count tables, the number for the reticulocyte life span (RLS) number would be 1.0.
Thus your equation would look like this:
100/[0.8/1] = 125 days
If your hemoglobin A1c number is a little higher than you’d expect given your current diet and lifestyle, and your red cell survival is longer than 120 days, your longer-lived red blood cells may be the reason.