CGM impact – is A1C all there is?

This is Caleb…

Caleb started using the DexCom Seven Plus continuous glucose system in September. This week was his first endo appointment since starting, a tidy three months later. I had no apprehensions about this appointment. In fact, I expected us to be in and out quickly. We just needed an update to Caleb’s prescriptions in addition to the normal routine.

I was however curious to see what impact using DexCom had on Caleb’s A1C. His A1C results have always been strong and we seem to keep chugging along.

This quarter’s results were no different. His A1C was unchanged. I wasn’t necessarily expecting a change, but I am a numbers and measurements kind of person. Even if it went up, I could say we were dealing with lows better. We had introduced a significant enhancement to his diabetes care. It seemed odd not to have it reflected in “the number”. If there had been any measurable difference, then I could attribute it to CGM and thus justify its use. His A1C was not giving me that justification.

So why are we doing this?

My biggest reluctance to starting CGM was asking Caleb to endure more discomfort without realizing a tangible benefit. He would have to be poked. He would have to wear the transmitter and carry the receiver. He would be the one who would be interrupted by all the beeps and alarms. Of course this is all to improve his glucose control, but that’s not measurable to him. I would be able to rest a little easier at night. I would be less stressed when separated from him. I would be less anxious between finger sticks wondering what was going on inside him. It seemed he was making all the sacrifices and I was getting all the benefit. So it would be nice to have something to point to to say yes indeedy, this is worth it – look, your A1C shows it. There’s no doubt about it. This was the right thing to do. It’s all here in black and white.

That is not the case.

Caleb’s doctor explained that when you already have tight glucose control, CGM typically will not change your A1C result. However, the quality of that result is often improved. In other words, the average of your blood glucose is still the same, but you are avoiding the high highs and the low lows that cancel each other out. The peaks and valleys are more subtle. The A1C remains unchanged, but it’s still a “better” A1c.

Hm. Okay. So do I believe that is the case with Caleb? It may be. I feel like we have caught things quicker and there are less surprises. We still have highs and lows, but they seem less severe. I don’t tend to go on feelings though. I like hard facts. Embracing this concept, although perfectly logical, isn’t all that easy for me.

After tweeting my concern (and doing a poor job of it because I led people to believe that I was a bit of a lunatic and wanted Caleb’s A1C lower and truly that was not my objective at all) I believe I got the justification that I was looking for. My wise friend, Melinda, helped me get there. She has a teenage son who has lived with diabetes since he was just younger than Caleb is now. Talking to her is like taking a magical trip into the future and getting a flavor of what it might hold for us.

I realized, with Melinda’s help, that an A1C isn’t the only way to measure the success of CGM. From the beginning I have stated that DexCom provided me some relief. I could see things before my eyes instead of worrying and wondering. I think I got so used to that so quickly, that I didn’t realize how much of an impact it has. I know that I am generally less anxious about Caleb’s BGs. I am wound pretty tightly to begin with, so it doesn’t take much to get me excited. There is a true, tangible value in decreasing the stress factor. It’s one that is very important to me. I know that Caleb has a lifetime of this management in front of him and how I handle it today will impact how he handles it tomorrow.

These are Melinda’s words that eased my worries:

“But HE benefits from having a less stressed-out parent. They certainly pick up on our cues. There’s a lot of value in that too.”

I know I do a good job of keeping Caleb’s blood sugars in tight control. I also know I do a poor job of hiding the impact the out of range numbers have on my psyche. That is where I need help and DexCom has provided it.

The answer is no, A1C impact is not all there is to CGM. There is much more. Thank you Melinda and all my Twitter friends for helping me understand that.

Yes! CGM impact for me is not even about A1C (mine is already decent). I want it for the peace of mind.

What does A1C mean to Caleb? I wonder how he thinks he is doing since the CGM? From the other side of the CGMS if I am not getting as many LOWs and HIGHs it’s a win for me. A1C is a batting average in away, if I batted .289 did I have a good season? Some would say no, I would say Did you see how many Homeruns I hit!!!

What I think is so AWESOME and important is that you and Caleb embrace new technology. Don’t get bumbed with an A1C number. It’s hard not to. I hope you guys have an awesome Holiday season. Thanks so much for all your input and speaking your mind. There are many parents out there that don’t have the courage to write down how they feel. You help many people.

Your profile shows perfect A1C numbers - even a healthy person will not have better numbers. The problem is that the A1C will not change much when the numbers are elevated for short periods of time. Thus it will not give you any feedback if you achieve improvements here. But research clearly indicates that the deviation within one day should be reduced because it also has negative impact on nerve system, eyes and blood vessels in general. This impact is more subtle and some kind of background stress. Your effords with the CGMS really aim at this deviation and your quality of life in general. Thus I think you two are doing great.


I understand your desire to see a measurable benefit. I firmly believe that I can control only what I can quantify. The magical number that you know exists and you are looking for might be the bg standard deviation. Studies show that bg variability is an independent risk factor. In other words, diabetics with identical A1C show a big difference in complications which strongly correlates to the bg variability. Take a look at

I am a DexCom user too and the 2 numbers that I am interested in I find in “Success Report”: “Mean Glucose” and “Standard Deviation”. My mean glucose is 98 with a standard deviation of 31. The mean glucose should predict my next A1C. The standard deviation will not show up on any lab report. It corresponds to what Caleb’s doctor refers to as ‘Quality of the A1C’. The standard deviation should dictate the mean glucose that I am shooting for. If I want to lower my mean glucose and therefore my A1C I need to improve my bg variability first. This will show up as a lower standard deviation. Being on shots I feel that there is not much room for improvement without severely impacting my quality of life. I am on the path to become a pumper. Maybe a pump will allow me to explore new territory.

I commend you and Caleb for your outstanding effort. I am an adult, have OCD and I am an engineer, all of which are beneficial to control diabetes. For a kid to control diabetes as well as Caleb does is truly remarkable. Fear not.

Thank you all for your input. The comments here and at “This is Caleb…” have been very meaningful. I felt like I had some closure when I wrote the post, but you all have given me even more peace of mind. I completely appreciate the value of standard deviation. At his point, I have nothing to compare to know if there is an improvement - just my gut. When Caleb started CGM, his graphs were what I call a liar’s chart - spikes after meals and then in range at the 2 hour mark. I was able to level that off almost immediately (to make a truthful chart) and because of that, I just expected there to be some measurable result. But hearing from all of you has been the measure that I needed - thank you.

Bill, Caleb will say that he thinks DexCom is great, but I know he’s just saying that. He knows I think it’s important and thus supports it. But I believe that he would much rather not have this thing buzzing on him or inserted in him. I know I would if there was no apparent benefit to me. But he trusts that I know what I’m doing. One day he’ll know better :).

awesome, I have thought seriously about getting DD a CGM - her hypos come really fast and she is very unaware of them. I think she is dropping low and night. Thankfully she has woken up a couple of times. but mornings are very stressfull for me, because i am scared of what I am going to find. I think once we get the hang of the pump I might ask for a CGM - I have read thought that they dont’ do much for children, but I think with an A1c of 11.3 that it would help her tremendously. Thanks for sharing!