Hemoglobin A1c

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Dr. Dennis Van Hoof, PhD, CLC

Red blood cells get sweeter with age.


Hemoglobin A1c

Red blood cells are the most common type of cells in your blood. A red blood cell picks up oxygen from your lungs, and then releases that oxygen at other places in your body. Hemoglobin is the molecule of those red blood cells that binds oxygen and gives the red blood cells their color. A single red blood cell has about 270 million hemoglobin molecules. Each hemoglobin molecule contains an iron atom, which is the component of hemoglobin that binds the oxygen; once oxygen is bound to the iron atom, it literally turns it into rust (hence the red color).

You have more than 20 trillion red blood cells; that’s 20,000,000,000,000.

There are several forms of hemoglobin in humans: A1, A2 and B. Besides oxygen, the glucose circulating in your blood also binds to hemoglobin A1, turning it into hemoglobin A1c (also called “glycated hemoglobin“). This happens all the time, as everyone (diabetes or not) has glucose in their blood (see Blog post “Blood glucose“).

Red blood cells

Red blood cells. [source]

Red blood cells can live up to 4 months, but most die around 3 months of age. New red blood cells are produced constantly, so your blood contains red blood cells of all ages: from 1 day old to 3 months old, and everything in between. Because a little bit of glucose binds to hemoglobin A1 everyday, old red blood cells have more hemoglobin A1c than young red blood cells.

You make 200,000,000,000 new red blood cells per day.

To explain this with a simplified calculation example: if 10 glucose molecules bind to a red blood cell each day, a week-old cell would have 70 glucose molecules, while a 3-month-old cell would have 900 attached to it (in truth, these numbers are much higher). When taking a blood measurement at a random time point, the average red blood cell in this example would have bound 450 glucose molecules (900/2=450). Your hemoglobin A1c level is expressed as a percentage of your total hemoglobin A1; 5.7% and below is considered a healthy value.


This is my most recent A1c test result. Even though I have type 1 diabetes, I manage my blood glucose so well that my A1c is within the “normal healthy” range.

The number of glucose molecules that bind to hemoglobin A1 per day depends on the concentration of glucose circulating in your blood. A higher blood glucose level on a certain day will result in more glucose molecules binding to red blood cells on that particular day. If this happens often, the number of glucose molecules per red blood cell will be higher on average, as explained with the following calculation example: if not 10, but 15 glucose molecules bind to a red blood cell each day, then a week-old cell would have 105, and a 3-month-old cell would have 1200 glucose molecules. The average at a random time would be 600 molecules per red blood cell (1200/2=600), which is much higher than the previous example of 450.

A hemoglobin A1c value of 5.6 means that 5.6% of all your hemoglobin A1 has glucose attached.

This is what tends to happen in diabetics who find it difficult to manage their blood glucose levels (see Blog post “Insulin and Diabetes“), resulting in an hemoglobin A1c that is above 5.7%. A (too) high hemoglobin A1c can be dangerous for several reasons:

  • It breaks open red blood cells (it kills them).
  • It makes blood cells sticky and clump together (big, sticky clumps can block your blood vessels).
  • It stimulates inflammation, which can cause atherosclerotic plaques that clog blood vessels.
  • It inhibits processes that lower LDL levels, resulting in elevated LDL levels.

All these negative effects of a (too) high hemoglobin A1c are damaging to your vascular system, and will decrease the supply of oxygen and nutrients to your organs. Especially organs that have a lot of very fine blood vessels will suffer the most, like eyes and kidneys, but also your toes and fingers. This explains why diabetics and pre-diabetics with high blood glucose from poor health management can develop diabetes-associated complications, like blindness, kidney failure and amputations.

If you want to learn more about a healthy and active lifestyle, without diets and restrictions or limitations, then follow me on social media like Facebook, LinkedIn and Instagram.

Also check out my website, becomeaninspiration.com and consider signing up for the personal diabetic lifestyle coaching or one of the online group workshops that I offer through video conference.

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Keep an eye out for my next blog, and I hope to see you soon to get you started on the journey to your new life!

—  Dennis


Dr. Dennis Van Hoof is a Certified Life Coach (CLC) with an academic PhD degree in Biochemical Physiology. By combining 20 years of first-hand personal diabetes experience with his in-depth scientific background, he developed a method to efficiently manage his own diabetes in a sustainable way. To learn how you can do this too, reach out for personal Diabetic Lifestyle Coaching or follow a group workshop that is specifically tailored to people with Type 1 or 2 Diabetes as well as pre-Diabetics and those at risk due to being overweight or obese. His clients thrive with their challenges and become an inspiration™ to others — with or without diabetes.

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