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Thinking Outside the A1C

Updated: Oct 27, 2020

If you have diabetes, you’ve probably heard your doctor talk about your A1C. As a refresher, it is a blood test that determines what your average blood sugars have been over the past 2-3 months. The American Diabetes Association recommends an A1C of less than 7.0% for most people, but you may have a goal slightly higher or lower than this general recommendation.

Having your A1C checked is an easy, quick tool to see how your blood sugars have been running. However, it’s definitely not the be all end all. Remember, your A1C is an AVERAGE of all your blood sugars. If you take a bunch of very high numbers and a bunch of very low numbers and average them together, you’re going to get a number somewhere in the middle. This can be true about the A1C.

Let’s look at the chart below. These are the blood sugars of two fictitious people that both have diabetes and both have the same A1C. When we really look at their blood sugars readings, we can see that their blood sugars are quite different. Tim’s blood sugars go up somewhat from meals, but not too high. Scott on the other hand, has very high readings after meals and is having a lot of low blood sugars as well. Despite having the same A1C, Scott is at higher risk for diabetes complications like heart attack, stroke, eye problems and kidney problems. The fact that he is having so many low blood sugars is also a concern.

Here’s a typical conversation that happens in my office quite regularly:

Patient: I saw my doctor last week and he said my most recent A1C was 7.2%. That’s really close to our goal, so he was super happy. He told me to keep up the good work as my blood sugars are great!

Me: That’s so good to hear! You definitely deserved the good feedback considering all the great changes you've made. If your A1C was a 7.2 that means that on average your blood sugars are around 160. Have you been checking them at home at all?

Patient: Not that often. Generally, in the morning my blood sugars are in the 90s.

Me: Oh wow, those are great numbers! Most people can’t get their blood sugars that low. Have you ever tried testing your sugars anytime besides first thing in the morning? Maybe after meals?

Patient: No, never. My doctor never told me I had to.

Me: Hmm…well I’m just thinking that if your average blood sugar is 160 and you have readings in the 90s, you might be having higher blood sugars as well, maybe over the 200s. Let’s do some math here- The average of 90 and 230 is 160.

Patient: What?!? I’ve never had a reading of 200!! My doctor said my blood sugars are great!!

Me: I’m not saying I’m right, but humor me. Start testing your blood sugars about 2 hours after meals and maybe once in a while before bed. Let’s just see where your numbers are at, and then you can go back to how you were testing before.

Fast forward to our next appointment- the patient is seeing that they are having readings up into the high 200s! I don’t feel good raining on people’s parades, and I’m not trying to make people feel defeated, but the A1C sometimes can give a false sense of security. To clarify, this is not the case for everyone. There has been plenty of times I’ve asked patients to test their blood sugars at different times and is turns out all their blood sugars, even ones after meals, are in range.

The moral of the story if that everyone's blood sugar patterns are different and they can change over time. Especially if you experience low blood sugars, you definitely could be falling into the trap where your A1C looks good, but your overall blood sugar control might still need some help. Try testing your blood sugars at various times of the day including 2 hours after meals. Be sure to share these numbers with your provider. We can't fix a problem if we don't know it exists!

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