10 Tips to Avoid Throwing Your CGM against a Wall


I always say that there are continuous glucose monitoring systems (CGMs) out there that require a higher learning curve than others. This is something you must know from the beginning because it will spare you a lot of frustration. There are some that require you to arm yourself with patience but the most important thing is that you read this post. This will help you skip having to spend a lot of time on this learning curve and you will jump from frustration to happiness in less time. It will also save you from sleepless nights and calls to the technical service or worst, their answering service. Here are 10 best practices that can be used with any sensor, although there are nuances that we will detail as well.

1 – Positioning

Choosing an appropriate site is essential and they usually aren’t the ones the manufacturer recommends. Although lately they have discovered they do learn from the patients (it took them long enough). My best sites to place sensors are undoubtedly my thigh, particularly the front pulling towards the middle and above, here is where my best and most durable sensors are well kept, my arm (and yes, you can place it yourself without help), the upper part of my buttocks (although uncomfortable to put it on your own, it is great if you have help, and during the summer it hides inside your swimsuits very discreetly, it is great!). The worst location has been without a doubt, my stomach.

My best areas are those that perhaps most manufacturers do not recommend at the beginning, and no sensor has worked better in the areas they recommended, in fact, they don’t last as long as the suggestion, and I’ve had problems with the adhesive. That’s why my suggestion is that you try and try alternative sites. I have seen sensors that have stuck in the most unsuspecting places like calves, forearms and the side of the chest! I acknowledge that there are places that I would not dare to try but if things went wrong with a site that I normally use I would try out any other alternative site. The question is always the same: “¿Does it hurt?”

Well it doesn’t hurt to put it on and it doesn’t have to hurt. Also there are systems so that it doesn’t have to be that way, (many of our preconceived notions are uninformed). That is why you have to try it out but take into account that the use of non-recommended sites can invalidate the warranty.

2 – Securing

The less the sensor moves, the better and the longer it will hold. To do this, some sensors provide some type of tape such as Medtronic’s Enlite sensors. In my case it gives me an allergy and I don’t use it but attaching the sensors with some additional help seems like a good idea for them to last longer and to have better results. However, the sensors shouldn’t be designed to use anything extra that doesn’t come with it. As a tip, if you use extra tape, always round the edges when you cut it (this will prevent it from peeling off easily).

3 – Waiting

Let the sensor sit for a few hours/days without activating it (let the sensor get acquainted or WAIT). One of my first frustrations was the inaccuracy of the sensors and what it took for them to give me decent readings. This was solved completely when I started to put on the sensors and letting them sit there without activating them. This helps your body get used to its new partner and for the sensor to get enough interstitial fluid, which is where the blood glucose is measured. With the Freestyle Libre I started attaching a sensor before the one in use was done, about 48h before time. I put on the Enlite sensors the previous night to start using them in in the morning (remember these cannot be submerged if they are not connected to a transmitter). Without a doubt, letting the sensor get acquainted made a big difference in terms of exact sensor readings, especially from Enlite sensors that seem to be more sensitive.

These are three golden rules, which we’ll call the holy grail and they are Positioning, Securing and Waiting to use as actions to be taken before starting a sensor. With these three rules you will avoid many unwanted headaches before you start using a new sensor.

Some actions that complement these three basic rules:

  1. Choose a site that involves minimal movement.
  2. Do not over tighten the inserter on the skin, just place it lightly.
  3. The faster the insertion, the less pain and generally less problems. DON’T look at the needle, don’t count to three, don’t think about it, just go for it.
  4. Once inserted check to see if it is in place and secure it with adhesive if necessary before positioning the transmitter, in the case of Enlite or Dexcom (if you use Skintac wipes make sure to cover all the area) and after positioning the transmitter use it again on the areas where the sensor is attached.
  5. Keep hydrated (it seems silly to say but this improves the life of the sensor in my case). Come on, don’t forget to drink water.

These are some of my tricks when the sensor is already live and the golden rule here is CALIBRATING (for those sensors that require it but little can be done for other types, probably even more than following rule two, SECURING).


  1. When it is time to calibrate make sure to do it when you don’t have active boluses (which theoretically mean greater glycemic instability). Never calibrate with arrows or at moments when there are glycemic changes, if it is unavoidable keep in mind that sensor readings afterwards will be below or above the indicated values in relation to the capillary value.
  2. Don’t make the mistake of going over the suggested number of calibrations. More calibrations don’t mean greater accuracy (I know, you may be used to calibrating if you detect a capillary and interstitial value that is light years away … but try not to do it). Enlite sensors from Medtronic or Dexcom require one calibration every 12 hours at the most, try not to calibrate more than three times a day.
  3. Additionally, the Enlite sensors used with the 640g pump have the particularity that the sensors get blocked out when two calibrations are not accepted. Therefore, if you do not accept a calibration do not recalibrate, instead follow the manufacturer’s guidelines in these cases.

Remember these are my tricks, of course you can do all this and get a bad sensor, or you can do none of it and things may go smoothly. Tell us about your tricks for your CGM sensors.

Editor’s Note: This was originally published on Republika Diabetes page.

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REPÚBLIKADIABETES is a particular project, because it is a three-way blog, of three people with long-term type 1 diabetes, who are friends and who write with a common goal to talk about everything that could be interesting and related to diabetes. Giving special priority to their knowledge, interests and personal experiences these bloggers focus on technology, news, maternity, travel, or nutrition. You can follow them on https://republikadiabetes.com, on Facebook Repúblikadiabetes, on Instagram @republikadiabetes and on Twitter @republikadiabet.