FreeStyle Libre experiences



My observation is that Libre shows slant arrow at 1 pts per min, whereas dexcom is 2. So while dexcom stays flat, Libre seems to oscillate more between flat and slant arrow when I am rising or dropping slowly. Dexcom stays flat arrow, but the numbers are slowly increasing/decreasing.

Time. Libre. Dexcom. Meter BG
9:14p. 92 D. 98 F. Next 110, Neo 99
9:20p. 87 D. 96 F
9:25p 82 D. 93 F
9:30p. 80 F. 90 F
9:40p. 74 D. 87 F
9:45p. 77 F. 87 F. Next 94, Neo 86.
9:55p. 71 F, 82 F
10:05p 73 F, 81 F.

11:10p 80 F, 86 F.

9:45 Bounce from 74 to 77, was that due to Neo BG check ?? What if not using FS Libre Neo strips, and use another meter ? I have not found option to log/enter BG from another meter. Does Libre try to correlate/adjust based on Meter BG ?
But dexcom also showed 5 pt drop. So maybe coincidence.
I did not enter BG to dexcom.

Since I am doing many more readings than listed, the battery is wearing down fast. I charged last night, and now about 1/3 left. May have to charge every day !
Update: after 2nd recharge, Libre is now lasting 2 days, and still showing full charge.

Summary for 50 minutes
Libre 19 point drop, several with slant arrow down. (92 - 73)
Dexcom. 17 point drop, always flat. (98 - 81)

Next… experiment with super fast up or down to get dexcom double arrows !!!

EDIT: According to manual, the Neo meter BG readings do not ‘calibrate’ the Libre. The sensor is calibrated ‘at the factory’.


These numbers are still very good!

I wonder if the Libre skews slightly low in order to make sure patients don’t end up too low. Emily’s numbers also skewed left.


It’s not clear to me if Libre takes meter input from Neo and tries to converge sensor BG readings with it, similar to when calibrations are put into dexcom. Using Neo strips is not required to use Libre.


I posted on a Libre Facebook group about the overnight false lows (not compression lows), and several responded that they have similar experiences. That being said, as of last night, I’m no longer reading low all night - it looked perfectly normal - so it may just be the sensor sometimes has trouble reading correctly at night for whatever reason. The change for me could just be due to other factors, though: slight diet changes, no longer nursing baby overnight, etc.

A similar trend I’ve noticed that you will see below is that, generally speaking, if I’m on the low end of my range, the Libre will read lower than my meter. If I’m on the higher end of my range, it reads higher than my meter. It’s still very close, so not really an issue to me; just interesting.

Life’s been crazy, but here are the numbers from the past few days - I’m depending on the Libre more and more (as evidenced by the fewer finger prick tests), since it seems right on with my meter almost all the time and I’m so preoccupied with things it’s easier just to scan and go. I love it. I’ve been making some diet changes, and this first day I don’t think I was eating enough carbs, which is why my numbers were so great. :slightly_smiling_face:

7:30am 67 Libre, 69 ReliOn
9:45 105 Libre, 90 ReliOn
12:15 64 Libre, 76 ReliOn
1:35 74 Libre, 80 ReliOn
6:40 73 Libre, 72 ReliOn
8:00 79 Libre, 81 ReliOn
10:00 86 Libre, 94 ReliOn
11:00 72 Libre, 75 ReliOn

5:30am 65 Libre, 71 ReliOn
9:40 112 Libre, 133 ReliOn
6:10 92 Libre, 92 ReliOn
8:00 110 Libre, 113 ReliOn
10:15 104 Libre, 97 ReliOn

11:20am 91 Libre, 81 ReliOn
7:00pm 139 Libre, 125 ReliOn
8:45 142 Libre, 136 ReliOn
10:00 113 Libre, 112 ReliOn


The difference between how it’s been reading at night (left) versus last night (right).


I also continue to get results that are pretty close.

Just now
Libre sensor 84 F
Dexcom 79 F

Verio BG. 88
FS Neo BG 92


Two things, as I read through this thread:

First, laying on the sensor (Libre or Dexcom) can cause false lows. The area around the sensor gets compressed and the amount of interstitial fluid decreases, so the sensor readings drop. Lay on the other side, or get up in the morning and the interstitial fluid equalizes, returning readings to normal. I have this issue if I wear my Dexcom sensor on my left arm because I sleep on my left side.

Second, keep in mind a “flat arrow” only means the bg “may be flat” or that it is increasing/decreasing only slightly. Dexcom claims it is only increasing/decreasing less than 1mg/dl per minute. That means you could rise or fall 30 points in 30 minutes and still maintain a flat arrow.


I’ve been wearing Dex and Libre sensors on the same arm for about 9 days and have noticed that Libre will show a 3 am low that is not noticed by Dex. Will keep using both for a few more weeks to see whats causing it.

So far I find the Libre to be usually pretty close to Contour Next One meter BG.


Last night was rough, still a problem this morning - first time eating out with the Libre, which went really well until I got distracted picking up our kids from the sitter and getting them in bed so stopped checking my BG. By the time I caught the delayed spike (I think a combination of the Afrezza wearing off and I had eaten a very fatty meal), I couldn’t get it back down - only managed to keep it from going higher with my corrections.

5:14 118R 109L
5:25 Ate dinner
5:35 109L dosed 8u Afrezza
6:00 Ate dessert
6:05 115L dosed 4u Afrezza
7:10 128R 127L (flat)
8:05 187R 165L dosed 4u Afrezza correction
8:20 167R 190L
Stayed at 190L
9:05 189R 194L dosed 4u Afrezza correction
Stayed at 194L until 10
10:30 178R 178L
10:38 164L
10:55 131L
11:15 135L
11:20 143L
12:15 120L
12:45 92R 92chm

I didn’t correct again at 10 because I was ready for bed and knew my pancreas would kick in at some point and didn’t want to risk a bad low in my sleep. Once things seemed to level out around 11, I went to sleep, only to be woken by baby at midnight, which was fortunate because that’s when I started dropping more rapidly. I ate a spoonful of peanut butter and stayed in range around 100-120 until morning (fasting 115 - much higher than my normal).

I opted for a lower carb breakfast - sausage and spinach, cottage cheese with a couple strawberries and almonds, and my Crio Bru w/a little sweetened creamer - and even though I dosed a bit extra since I was already at 115, I’m now at 164 and rising according to the Libre (checked meter 15 mins ago and was at 144, dosed a 4u Afrezza correction). Today will be interesting.

Overall I was impressed with how well the Libre kept up with the spikes/drops and all the Afrezza doses. I’m glad I had it, because I might not have thought to check after that 7:10 check with my meter until bedtime (depending on how I felt), and by then who knows how high my BG would have gotten.


I’ve been trying to get my own rx for a libre filled and thus far it’s been a total donkey show. I can’t help but think that they are nowhere near ready for prime time. Quickly losing interest myself.


Try Walgreen’s, they seem to be able to sort it out.

FYI so far the Libre has withstood all challenges I have thrown at it.


Nearest walgreens is about 100 miles away-- I wonder if they’d mail it to me from there?


Got me there, I’m still learning the ins and outs of pharmacies. My local pharmacy “could not get the Libre from the supply house” and faxed my prescrip to a nearby Walgreen’s. For what it’s worth, the pharmacist there said they’ve been flying off the shelf.


My Walgreens can’t get them either. If you can find one that can get it, they will mail it.


My local Walgreens did not have it in their system, but CVS was able to get it in one day.


@Pianoplayer7008, @MM2, are you still getting good readings?

@Pianoplayer, you have gone through more than one sensor by now, right?


MaryPat, I’m on sensor #2 and overall satisfied with the Libre BG readings. it reads low sometimes, high sometimes compared to Contour Next One. For me, it has been close enough to be useful. I’ve got a third sensor to use in mid Feb to complete my trial.

I have been swimming in the ocean daily with the Libre sensor, even though the sensor is not rated for salt water. Did not seem to affect it.


Thanks very much for the info, @John58

John, this part of your message put me in a pensive mood. As I look outside my window, it has been snowing almost non-stop for 24 hours, with a good 6" of accumulation :slightly_smiling_face:

That is excellent news, as it the fact that it remained attached through the 14 days despite the salt water. We have a hard time keeping the Dexcom sensor on through a week when swimming daily.


I got good readings throughout the 10 day session.

I only used the one free sensor, and it ended last Wed. It is not covered by my insurance, and I recently filled my dexcom sensor supply. So will not likely use again unless I can get more free samples from endo.


I’ve swam in the Black Sea with my Dexcom and Omnipod, which aren’t rated for saltwater. The Dexcom survived fine. I killed 3 of 6 OmniPods in saltwater though. It’s one of the reasons I went back to Tresiba.