What is HbA1c, and why does it matter?
HbA1c is a simple blood test that measures your average blood sugar levels over the past 2-3 months. Here’s why it’s important.
The HbA1c test, also known as the hemoglobin A1C or A1C, reflects your average blood sugar levels over the past 2-3 months.
When sugar enters your bloodstream, it attaches to hemoglobin, a protein in your red blood cells. Higher blood sugar levels result in more sugar being attached to your hemoglobin. HbA1c is a measure of the percentage of your red blood cells that have sugar-coated hemoglobin.
Doctors generally test HbA1c for diabetes screening, diagnosis, and management. However, blood glucose is an important marker for everyone and can be a helpful metric in monitoring your overall health. For health and fitness enthusiasts trying to optimize our health, measuring HbA1c can be a valuable tool.
Fasting Blood Glucose vs. HbA1c
Many people get their fasting blood glucose levels tested when getting routine labs done. While it’s important to see what that number is, it’s a point-in-time measurement and can be affected by a number of things, such as the timing and composition of your last meal, activity levels, stress, and hydration level. Because HbA1c reflects your average blood sugar levels over the past 2-3 months, I find it a more valuable measurement in assessing how my diet and lifestyle changes are affecting my blood glucose.
According to the American Diabetes Association (ADA), HbA1c results fall into three categories:
Less than 5.7% signifies normal and healthy metabolism
5.7% to 6.4% signifies prediabetes
6.5% or higher signifies full-blown diabetes
So while most medical doctors would say any result under 5.7% is normal, is it optimal?
Consequences of Sub-Optimal Levels Over Time
There are a number of studies (including this, this, and this) that indicate that chronically sub-optimal HbA1c levels damage tissues, blood vessels, and your organs most susceptible to glucose, leading to an increased risk of certain cancers, cardiovascular disease, stroke, diabetes, and increased annual brain shrinkage.
This is why, despite what the ADA says, many integrative medicine doctors have tightened their target A1c to between 4.6% and 5.3%.
How HbA1c Correlates with Average Blood Glucose
While there are individual differences that can alter how A1c correlates with average blood sugar, generally speaking, it looks like this (you can do further calculations here):
A1c 5.0% → Average Blood Glucose 97 mg/dL
A1c 5.5% → Average Blood Glucose 111 mg/dL
A1c 6.0% → Average Blood Glucose 126 mg/dL
A1c 6.5% → Average Blood Glucose 140 mg/dL
The “ideal” range for your blood sugar is generally considered 80 - 110 mg/dL. Even accounting for some spikes, we’d be targeting an average level under 100 mg/dL.
While there are many optimizers that target an A1c even lower, I’m personally targeting a value of 5.0%. I’m not quite there yet, but I’ve made progress this year.
What I’m doing to improve
Our blood glucose levels are affected by a number of things beyond just carbohydrate intake, including sleep, exercise, stress, protein intake, and fiber intake. The most important baseline things I was easily able to do to improve my levels were reducing my intake of refined carbs and sugar and improving my sleep.
My baseline diet and lifestyle are in a good place. Over the past couple of months, I’ve been focusing on increasing my fiber intake, eating even fewer processed carbs, and eating out less. I’ll do another set of labs in the next month or so and will update you on my results.
What about Continuous Glucose Monitors (CGMs)?
I’ve used both Levels Health and Nutrisense. They both provide CGM hardware from Abbott Labs; Levels recently started offering Dexcom devices too. I’ve gotten significant value in using these services to baseline how my body is responding to food and lifestyle changes. Given I’m not diabetic and because I don’t change my diet regularly, I’ve found that I get the most value by periodically using a CGM to assess how specific changes are affecting my blood glucose.
I’ve found that the devices are often quite off in their absolute measurements for me, so focusing more on relative changes, like how much I spiked after a specific meal, has been more valuable than focusing on whether I’m in a specific range. A fasting finger stick blood glucose test can be used to calibrate these devices to get more accurate absolute results, and it seems like Levels is increasingly changing its app to be more focused on relative changes too.
Periodically using a CGM has also allowed me to experiment to figure out how various “hacks” work. Some examples include consuming fiber and protein before carbs, going for a walk after carb-heavy meals, and things like cooling and reheating rice before eating it. On Instagram, glucosegoddess has many eye-opening strategies and hacks.
The HbA1c test reflects your average blood sugar levels over the past 2-3 months. While anything under 5.7% is considered “normal” by most doctors, that’s not optimal, and there are likely health consequences of sub-optimal levels over time. Many integrative medicine doctors have tightened their target A1c to between 4.6% and 5.3%. I’m targeting under 5.0% as part of optimizing my health. Focusing on my diet this year has improved my results, and I’m now trying to eat more fiber, even fewer processed carbs, and eating out less to try to hit my goal. CGMs can be a useful tool to baseline how your blood sugar levels respond.
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