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How to be successful with your continuous glucose monitor

December 08, 2016 by Scott Johnson

Strategies for success

I wasn’t sure what to think. Once I put on the CGM, I could always see how crappy my blood sugars were. That part was shocking and a little upsetting – but where would I be if I never found out how bad things were?

On the other hand, it was immediately helpful to have the high and low glucose alarms. I think that part is obvious. But wasn’t there more to it? Wasn’t just reacting to alarms leaving a lot of potential benefits untapped? Indeed. But whenever I tried to make sense of everything I got overwhelmed and gave up.

In 2013 I attended a talk in San Diego, CA (now home to mySugr USA’s offices). The person giving the speech was Gary Scheiner (now the head coach for mySugr Coaching).

Gary talked about the overwhelming amount of information coming at us from devices like continuous glucose monitors – a new phenomenon for us! He said trying to make sense of the entirety of it is a recipe for going crazy. You have to approach it with a specific goal or question in mind, which was a big revelation for me.

Dexcom G5 transmitter and iPhone

Dexcom G5® Mobile CGM System

Some examples

Let’s work through some hypothetical examples (note: these don’t take into account things like exercise, illness, stress, alcohol, etc.).

Goal: Verify insulin to carb ratio (are you taking the right amount of insulin at mealtime?)
Process: First things first, if your basal rate isn’t working right then all bets are off. You might want to do some basal rate testing first. Once you’re satisfied there, then this one is relatively easy.

  1. Start with a stable blood sugar (no active insulin from a previous rapid-acting insulin dose).
  2. Eat something that’s SUPER easy to carb count and simple (not high fat/protein). You need to be confident in the accuracy of your carb counting for this, which means that a packaged item might be the best choice (the ironies of diabetes health).
  3. Take your mealtime insulin, eat your meal.
  4. Watch your CGM for the next 3-5 hours.
  5. Ideally, you’ll end up back where you started. If you ended up higher, you didn’t take enough insulin. If you ended up lower, you took too much insulin.

Before jumping to any conclusions, repeat your experiment to make sure your results weren’t from something else and talk to your healthcare provider before making any medication adjustments.

Goal: Verify correction factor (are you taking the right amount of insulin to fix high blood sugars?)
Process: Again, first things first, if your basal rate isn’t working right then all bets are off. You might want to do some basal rate testing first. Once you’re satisfied there, then this one is also relatively easy.

  1. Start with any moderately elevated blood sugar. Lucky for us, our pancreases are broken and we bump into these often enough. (Again, no active insulin from a previous rapid-acting insulin dose)
  2. (Moderately elevated works best for this because REALLY high blood sugars are usually a bit more stubborn and you’ll want a whole different set of experiments for that)
  3. Take your correction insulin.
  4. Watch your CGM for the next 3-5 hours.
  5. Ideally, you should end up near your target blood sugar. If you ended up higher, you didn’t take enough insulin. If you ended up lower, you took too much.

Before jumping to any conclusions, repeat your experiment to make sure your results weren’t from something else and talk to your healthcare provider before making any medication adjustments.

iPhone with a Dexcom 5 CGM graph

Landscape view of glucose info in the Dexcom G5® mobile app

BONUS: You can also figure out your duration of insulin action with this experiment by watching how long it takes for your blood sugar to stop dropping.

Gary also mentioned working on one piece of the day at a time. For example, spend a few days watching what usually happens at breakfast, then make a small change to your meal, your insulin timing, or your therapy (with the blessing of your healthcare provider), and see what happens. Keep exploring little changes until you’re happy with the results. Then explore another meal or another section of the day. Sounds logical, right?

How to analyze

I use mySugr to keep track of what I ate and when as well as the timing of my insulin. I also add any tags or notes that might be relevant. I use an iPhone, so my Dexcom automatically feeds a graphical line into the mySugr app via Apple Health, which I can see on my screen and in the PDF reports (the PDF reports are a mySugr pro feature).

One section of the mySugr PDF report

A section of the mySugr PDF report

I can also scroll through individual entries in mySugr – this approach would work fine if you don’t use mySugr Pro.

mySugr app entry screen

Detail view of an entry in the mySugr app

Additionally, my Dexcom G5 continually feeds the Dexcom CLARITY® data management system. Dexcom CLARITY has evolved a lot recently, and I was pleased to see that in addition to quick pattern analysis reports on the iPhone app, I can also access more detailed information from the Dexcom CLARITY webpage. I like that I can hover my mouse above the graph for detail cards with exact numbers.

Glucose detail in Dexcom CLARITY

A section of the Dexcom CLARITY® report

Using these tools gives me more than enough information to answer the question I’m asking. And it’s also important for me to have reliable data to show my doctor when talking about therapy adjustments.

But it’s hard to remember

I have to remind myself about this strategy over and over again. I get wrapped up in the daily stream of numbers and alarms and forget to take advantage of the potential this powerful tool offers.

How about you? If you’re using a CGM, do you feel that you’re making the most of it? If you’re not using a CGM yet, are you concerned about data-overwhelm? Leave a comment and let me know.

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  • Kapitolina

    Thank you for this post! As for my experience, I had hard first week with CGM, I was so upset when I saw how even healthy food like cinoa affects my blood sugar. For now I adjusted my diet pretty well, my blood glucose range between 60-150, however I still have night time lows and I’m trying to get rid of it. And its very interesting to see how physical activity affects BG, some times it goes low, some times high. So I still have a lot of food for thoughts.

  • Thanks for reading and taking the time to comment, Kapitolina! Sounds like you’re well on your way and are doing great! Good luck with those overnight lows – please keep us posted!

  • Dan Streiffert

    I like that you can load your CGM data from Dexcom into MySugr. I’m using the Tandem T:slim insulin pump with the bult-in Dexcom CGM. Is there some way to load the CGM data from the T:slim?

  • Hi, Dan!

    Cool! I’d love to try that one! No way to get that Dexcom data via T:slim yet, but we’re always working on ways to make the data transfer easy & seamless. Hang in there!

  • Dan Streiffert

    Scott,
    I can download an Excel (csv) file from the TConnect uploader with the CGM data. Is there a way I could use that to upload to MySugr?

  • We do have an importer function on our website, but we’d need to massage the data handling a bit to be compatible with the T:slim formats. I can’t remember off the top of my head if we’ve looked at the T:slim format before or not. It could be a nice workaround for the time being. Our dev team has their hands full (as always, right?), but if you’re willing to send me your file I’m happy to ask them to take a look at it. Shoot a message to support@mysugr.com to my attention and I’ll get it over to them. Thanks!

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