My Overwhelming First Days with a Dexcom CGM


Overwhelmed. That’s not how I was expecting to feel during the first two days I was connected a Continuous Glucose Monitoring System. As a person with diabetes who loves to study her blood sugars and learn about adjustments I can make for tighter control, I expected to find the Dexcom CGM instantly supportive and informative.  I expected it to feel like an amazing insight into diabetes management that wouldn’t otherwise be possible. 

I know many other people with diabetes who wear a CGM, and I see their posts and conversations on Facebook, Twitter and in online communities. And yet, nowhere in any of those conversations did I ever see anyone express feeling totally overwhelmed by the constant influx of numbers and data during those first two days. As someone who isn’t usually anxious or stressed, I was sincerely surprised at just how anxious I was.

You see, I’ve been managing my type 1 diabetes “old-school” since I stopped using an insulin pump in 2004 after a malfunction in the pump.  So today, and for the past 9 years, I’ve been taking Lantus and Novolog with syringes. (Nope, I don’t even like to use pens.) I check my blood sugar between 6 to 10 times a day, and my system works well for me.  My recent A1C of 6.4% proves “old-school” is just fine, but with an endless series of severe lows (around 30 mg/dL) at 3 a.m. most days of the week during the past 6 months, I started to think there had to be way to do this better.  Additionally, I have plans to become pregnant next year and intend to maintain a 5.8% to 6.0% A1C prior to and during pregnancy.  I knew the best way to do this would be to get a CGM.

Choosing a CGM was easy: I had done an initial 3-day CGM trial for insurance purposes with a Medtronic CGM and within 24 hours the site of the sensor on my stomach was painful and desperately itchy. After removing it, the sensor itself was covered in blood, and the bloody hole in left in my flesh was disturbing. The ordeal left a dark blue bruise that lasted for over a week.

DexCom’s sensor, however, gave me zero skin issues. No irritation. No pain. No blood.  And I was so pleased to see that the entire set-up for inserting the sensor was far less painful and tedious, and the site itself where it sits in my skin is nothing like an infusion site for an insulin pump.

But when it came to using the data the Dexcom CGM was giving me on my blood sugar levels, the first day was a self-induced roller coaster nightmare. What left me feeling so anxious wasn’t actually the number on the screen or the programmed alarms I’d been advised by three experienced, certified diabetes educators to set at 75 mg/dL and 140 mg/dL. Instead, it was the arrows. After a meal, it’s only logical and normal that anyone, even a non-diabetic, would have a rise in blood sugar, but to see two arrows next to the number, going straight up (implying a rise of 3 mg/dL per minute) or even just 1 arrow pointing upwards (implying a rise 2 mg/dL per minute) gave me immediate anxiety.

As I watched the arrows, I wanted to stop them, get them to turn around–quickly. So, after confirming the CGM number with my glucose meter, I took a correction dose of insulin not based on the number it was at that moment, but based much more on the anxiety I was feeling over the image of that upwards pointing arrow.

The silliness of this, of course, is that having not used a CGM before, I have my insulin doses very fine-tuned for the sake of accuracy and preventing anything above 180 mg/dL after a normal meal. And so I should have trusted my knowledge — not my emotional reaction — and given my insulin injection time to do its job.  And sure enough, within the 30 minutes the arrow leveled out.  But… then, thanks to the unnecessary correction dose I’d given myself in the panic, my blood sugar started plummeting, which appeared on the CGM as an arrow pointing downwards.

Now, you would think that seeing a down arrow would bring relief after seeing that upwards rise, but no, this freaked me out, too. I tell you, I literally threw all my prior diabetes-management knowledge out the window, and was operating on emotional hyper-drive for those first two days. Instead of consuming 10 to 15 grams of carbohydrates for a low blood sugar like I had been doing for the past 15 years, when I saw the downward arrow eventually passing 80 mg/dL, I consumed another glass of juice and another glass of juice over the course of 30 minutes. And even though I am well practiced in the art of sitting on my hands and waiting for a blood sugar to recover from a low after consuming 10 to 15 grams of carbs, making sure not to overcorrect, the sight of that downward arrow was terrifying.

Day Two of chaos proceeded much like Day One, with the addition of two much needed gluten-free, doughnuts that aren’t really a regular part of my weekly diet. I was exhausted. I had exhausted myself, both emotionally due to the anxiety, and physically due to the crazy ups and downs I was putting myself through with too much insulin and excess carbohydrates.

By the end of Day Two, I promised myself that I would manage my diabetes just like any other day. I would let my insulin do its job. I would let any carbohydrates for lows work their magic in the time it takes. I would follow my usual 75 grams of carbs-per-day lifestyle. And most importantly, I would let the arrows settle in their place, resisting the urge to overreact.

Those arrows are an amazing tool. They allow  me to know not just what my blood sugar is during any given moment, but also which direction it’s going–but I learned the hard way that even when they’re completely accurate, they can very quickly change from an arrow pointing upward to a slanted arrow (implying a rise of only 1 mg/dL per minute) and then, a sideways arrow implying little to no change at all. It can even go from one upwards arrow suddenly to a sideways arrow, which leaves you trying to decide what is causing the rise and just how long you should to wait before acting.

Today, I’m happy to say that after more than a month of being hooked up to the Dexcom CGM, I adore it, appreciate it, and benefit from it. Now I feel much more comfortable seeing the arrows and understanding not just what they mean (because that part is in the manual) but how to actually use them in a way that safely benefits my blood sugar goals in a life with diabetes that existed for the past 15 years without this high-tech gizmo.

And, thanks to the CGM, I can see that those 3 a.m. dips in my blood sugar every night are actually very sudden and most likely due to peaking of my Lantus insulin dose taken before bed. (Lantus is said to peak approximately 6 hours after injection, and yet, for most of the past 8 years I’ve been taking it, I’ve never had an issue with this until now!) And I’m excited to be working with Gary Scheiner, 2013 CDE of the Year, through his services at IntegratedDiabetes to come up with an out-of-the-box plan with long-acting insulin Levemir to help tackle those 3 a.m. lows.

Thanks to the CGM, I’ve had only one blood sugar below 55 mg/dL during the past several weeks, and any other lows I was able to catch before they dropped below 65 mg/dL. This is an incredible thing for someone who is sensitive to insulin (one unit easily drops me approximately 125 mg/dL).

I can also count on one hand how many times my blood sugar has risen above 180 or 200 mg/dL because, with a logical (not emotional) response, I can use that upward arrow to catch the high before it’s so high.

I adore this little gadget, I do, but I want you to know, if you’re anything like me, then the first few days can be a little overwhelming. Just as losing weight, moving to a new house, changing how you eat, or even getting a new job can require a little time to adjust in terms of how you manage your diabetes, I think the same is just as true when you add in an awesome tool that is designed with the sole purpose of benefitting your diabetes. At least, it certainly did for me.


Ginger VieiraAuthor of “Your Diabetes Science Experiment” and “Emotional Eating with Diabetes,” Ginger Vieira has lived with Type 1 diabetes and Celiac disease since 1999. Today, she is a certified cognitive coach and diabetes coach at Living in Progress, creates diabetes video blogs for her YouTube Channeland creates regular freelance content for Diabetes Daily and other publications. In 2009 and 2010, Ginger set 15 records in drug-tested powerlifting with a 308 lb deadlift, 190 lb. bench press, and a 265 lb. squat. She lives in Vermont with two dogs and her fella.

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4 years ago

I have been having this experience my first week on the dexcom. The alarms and data have me over compensating and stressed. I’m doing my best to keep it level. Glad to know I’m not the only one. Thanks!

6 years ago

I have been type 1 for 39 years now. Since I was 1 year of age. I have been on a pump for about 12 years maybe. Looks like I may be getting the new T-SLIM with the Dexcom unit. Does it’s accuracy vary depending upon the area it is inserted?


7 years ago

Thanks so much for posting your experience for others like yourself! I’m going to my doctor today to learn how to use my new Dexcom & I have found this very helpful. I can get very anxious and over correct with insulin  and/or carbs and reading about your experience has helped me prepare for this new experience. BTW, I also do things “old school” with a syringe and vial. Maybe because I was diagnosed 26 years ago, but my A1C is 6.3 so it does work for people like us. Thanks again.

8 years ago

Biggest issue with all CGM’s is that they do not measure or indicate blood glucose – they indicate glucose within interstitial fluid. Blood glucose fluctuations are a very transient response that is dependent upon many factors for me. How fast my BG responds to food, for instance, during dinner, changes drastically from day to day. I think I may be more unique than common in that my lifestyle is heavily dependent on occupation – stress and schedule do not go hand in hand and both change very frequently. Make matters worse – I am most often in a public setting – where I… Read more »

8 years ago

Did you ever try to take Lantus in the morning? In this way you will never have deep lows during the night. I am doing so and it is fine. You will have a low in the afternoon but you are awake and it is easier to treat. If you take Lantus shot in the morning the dose is different, you need much Lantus.   I am also very sensitive to insulin, 1u/80mg/dl. I have already a baby and Lantus helped me during pregnancy, with Levemir was awfull, it does not cover the whole day, it needs two shots. Excuse… Read more »

Khürt Williams
8 years ago

I guess I have a different relationship with technology. I tend to trust it until or unless it fails.  I’ve been on MDI since I was diagnosed with T1 in 2006.  I’ve had my Dexcom G4 for about two months and I had no problems adjusting to it.  I can’t imagine being without one.  Those graphs let me see trends and based on knowledge of my food (most of my meals are home made) and insulin dosing I can correct for inaccuracies.  I guess we each approach technology differently.

8 years ago

Wow, thank you for this article.  My husband is type 1 and was diagnosed at 2 years of age.  He is at the point where he is so used to the “low feeling” that sometimes he misses how low he really is.  He has thought about CGMs before and I have thought that he would do well with one.  I can see how the overload of information could be stressful at first though.  I appreciate your perspective!

Jennifer Jacobs
8 years ago

I remember having the same experience on my beloved Abbott Navigator (RIP!). One look at those arrows going up and I was stacking insulin (and then crashing to 30 mg/dl). They should include a warning in the user’s manual about the first couple days — just a little acknowledgement that you may be tempted to overreact would be useful. I also find that the constant beeping and checking is itself very stressful. It’s like getting on a scale 25 times a day — you constantly judge yourself by the number. Granted, I adore my CGM and would not want to… Read more »

Scott Strumello
8 years ago

I got a Dexcom in February but did not start wearing it until April (I was travelling this spring and didn’t have time to deal with it before, so I waited until I saw the trainer before trying it).  Dexcom is far from perfect.  The training consisted of YouTube videos until I called and insisted I have a real person show me how to use the thing my insurance company just spent several thousand dollars on.  Inserting the sensors can be confusing the first few times, but I’m over that now.  I still find the readings on day 1 are… Read more »

Michelle S.
Michelle S.
8 years ago

Yes, there is a definite learning curve!  I used the Medtronic CGM three years ago and didn’t stick with it due to some of the frustrations.  But I am using the new Enlite now (its been available in Canada since the spring), loving it (less tape than the old Medtronic CGM so finally no itching for me) and I am having way fewer lows.  So worth the effort.  However, we need more educators trained in the CGM so PWD are willing to take on the adaptation process.  Glad you are finding it helpful now!

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