Libre vs. Dex: A Sugar Surfer's Experience


Sugar Surfing™ was born out of asking a question. After adopting an early generation real-time CGM almost 10 years ago, I was also wearing an old insulin pump (Deltec Cozmo). The question I asked was simple: which one of these two devices attached to my body was more important to me? Both were helpful, but which one could I best do without?

After over 30 years of pumping insulin I chose to go back to multi-dose insulin (MDI) and just wear a CGM device. Using the data and trends visible from the CGM, I was able to discern a set of personal self-care guidelines based on close observation of my unique eating behaviors, activity and insulin dosing decisions. What soon became clear was that my blood sugar dynamics were similar, but never identical from day to day. There was always some degree of uncertainty. But since I could visualize the glycemic trend line, I could see these changes before they could come to fruition. It wasn’t long before I was preventing problems before they happened. I would define that as “pre-empting” in the book Sugar Surfing.

Recently, I asked myself another question. After years of Sugar Surfing with a current generation CGM (Dexcom G5 as shown above on the right), how would the Abbott Libre Freestyle (as shown above on the left) system compare? This is not a new technology around the world, but only recently approved for use in the US for real time CGM use in adults.

In the past I had worn two Dexcom CGM units at the same time and compared the results. There were some minor variances even when the units were calibrated simultaneously and inserted at the same time. The experience highlighted to me that every technological device possesses variance, even when those devices are as close to identical as possible.

This time, I simultaneously started wearing a new Dexcom G5 sensor and Abbott Libre (newly approved US version). The Dexcom has a two hour wait time. The Libre in the US requires a 12 hour “warm up”. This is first obvious difference between the two.

Insertion of the Dexcom requires help if worn on the arm…or great dexterity. I use the former. The Libre sensor is much easier to insert. The applicator is spring-loaded, unlike the Dexcom which requires a smooth forceful motion on the plunger. Libre has a relatively pain free insertion. Advantage Libre for ease of insertion. The external sensor housing has a slimmer and sleeker profile. The Dex enters at an angle and is longer, but I can’t speak to how much deeper it penetrates than the Libre.

Adhesives are the bug bear of attachable diabetes tech devices. Reports of allergic reactions to sensor and insulin pump site adhesives are common in the #DOC. In some persons, adverse adhesive reactions can derail use of these tools. There are many homestyle remedies for adhesive allergies and some strategies do help, but some are still unable or unwilling to put up with the additional work of dealing with skin problems with adhesives.

I am fortunate to not have skin reactions to any adhesives. My reputation remains intact with the Libre. Compared to the Dexcom G5, the Libre sensor adhesive strongly attached to my skin well. Both were exposed to the shower at least once and sometimes twice daily. Neither came off or even peeled up. But this observation is invalid since I also apply a second tape layer (IV3000 dressing) above the Dexcom G5 sensor which increases the surface area and holds down the edges of the G5 sensor pad and adhesive. When it was time to remove the Libre sensor after 10 days, it was quite well attached to me and took some effort to remove. The Dexcom sensor unit peeled off relatively easily.

I use an Abbott Freestyle Lite meter to calibrate my Dexcom G5. The Libre requires no calibration; that’s done at the factory. The Libre still has a built-in meter to use when confirming out of range readings. The sensor will prompt the user to check when readings are changing rapidly (up or down) or if they fall outside your programmed target range. The target ranges for both devices are user defined.