Libre vs Dexcom G5 trial run accuracy

Back in mid-January I took advantage of the free Abbott Libre reader and sensor to try it out. I also bought 2 extra Libre sensors to make this a full 30-day trial. I used a Contour Next One meter for manual BG tests and wore the Libre and Dexcom sensors on my left arm. The first 20 days of the test occurred during a vacation so there were daily swims in the ocean, hikes, bike rides, golf etc. plus a lot of rushed pre-bolussing, carb guessing, overeating, alcohol, etc. After I got back, I played hockey twice with my double sensor setup. In other words, I tested during a time when some highs and lows are likely to happen and I gave the sensor adhesion an endurance trial.

Here are the results:
(BG readings compared to Contour next manual BG tests):
148 manual BG tests total, range of 59 to 231 mg/dl on Contour Next One meter, average 135 with SD of 42.

% within 10% plus or minus: Dexcom 49%, Libre 60%
% within 20% plus or minus: Dexcom 84%, Libre 95%
Dexcom G5 average variance from manual BG test was -6 mg/dl, Libre average variance was -2.

Admittedly this 30 day trial included some spells where the Dex calibration was obviously thrown off by me squeezing in hasty calibrations when I should have waited. I considered those part of my day to day and included them in these stats. I also had a lot of rising and falling BG when testing and the results probably reflect the lag in readings by both devices.

Anyway, I wanted to throw these numbers out there for those considering the Libre. Overall I am satisfied with the Libre and do not have concerns about the accuracy (compared to all of the other options). The workarounds for lack of alarms and the 12-hour warmup are discussed in other posts. The sensor insertion is a breeze and the “stock” adhesive on the sensor performed flawlessly.


Wow! Even though I am having GREAT success with my Libre, I’m still impressed with these results. Thank you for sharing (and by the way, sounds like a fun vacation)!


Just wanted to ask you about the times you spent in the water swimming:

i wore a trial run of the Libre for 14 days and swam 5 days a week for 1.5 - 2 hours each day. the first run went flawlessly. the second trial, though, the sensor fell off after just 5 days; i called Abbot and they told me that the Libre was NOT waterproof (even though my CDE promised me that it was). when i called the rep on the phone, i was told that even though the sensor fell off after just 5 days, it was not guarenteed and they would not replace it.

so, all of that being said, i am very curious about your experience and how well the Libre sensor stayed put.

looking fwd to hearing back from you, thanks,

Daisy Mae


Hi DM! I never had a Libre sensor peel off or fail during my trial run in salt water. I got back on Dex after that trip with only occasional use of Libre. Maybe they changed the adhesive?


@daisymae, I was wearing the Libre just recently and spending about an hour in the pool maybe 4 days a week (sometimes 5). I didn’t have any problems with it falling off. I use Skin Tac wipes on my skin where I’m applying it. The two times I’ve forgotten the Skin Tac, my Libre has fallen off by day 6 or so… and that was even just with running and sweating. The Skin Tac seems to be all the difference to me. Can’t tell you how nice it is to hear you talking about swimming again. :heart:

@John58, I still wear my Libre and Dexcom AND my Guardian. :grin: The Dexcom is the one I’m transitioning to, the Libre I am learning to use for exercise (and am consistently impressed with it I. General), and the Guardian I wear for the laugh. :rofl: I shouldn’t say things like that out loud, but it’s true. Really, I didn’t realize how impressive the Libre was though until wearing them all and running little tests. It’s a hardy little bugger, the Libre, and I hope the 14 day sensor is as good.