Freestyle Libre, whaaaat?

Well, we finally got a Freestyle Libre for my son. He’s had it on for 5 days so far and we have been testing his blood sugar by finger poke and the interstitial fluid by scanning. There are times the readings can be off by a few numbers and the rest of the day, there are 10 to 40 point gaps in the readings. This is new technology to us, we’re coming up on his 9 year diaversary (he’s 10), and I am just as confused now as I was then.

I’ve tried googling but just keep coming up with medical jargon that is beyond what my brain wants to accept reading (ie: really big technical words). So, any help would be much appreciated.

I know this makes me sound like I’m stupid but I swear I’m not. I’m just a lost mom trying to figure this out.

@FoxFaerie on top of all this stress you think you sound stupid??? C’mon you have to learn to be more gentle with yourself.

You blood tester is accurate to +- 15%. Meaning if you stick your finger and it says 100mg/dl then your real and actual blood sugar is between 85 and 115mg/dl or a spread of 30. If your machine said 200mg/dl your real blood sugar is between 170 and 230mg/dl or a spread of 60.

The libre, similar to the finger stick is roughly +- 15% accurate. On a good day there can be a spread of 30 between a finger stick and Libre if your blood sugar is below 120.

Consider that blood sugar changes faster than interstitial fluid. So if blood sugar is rising, the Libre may be more than 30 lower than a finger stick. The 2 may not match at all until a fast rise or fall flattens out.

To sum it up, a spread of 20-40 in difference between Libre and a finger stick is possible and even likely. A larger spread is likely during fast rises or falls. And a larger spread is more likely at higher numbers.

Also, this is common to Libre, Dex, Guardian, and ANY interstitial based measurement. Cheers!

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Hi Jennifer @FoxFaerie, to add a little bit to what @Joe said, I’ll add that even after more than 60 years of trying to figure out this “diabetes thing” I’ll get flustered when finger-sticks, monitor readings and “what I feel” are not in sync. The first few days or weeks with new equipment are the most stressful because we / I am wondering if I’m reading this thing correctly.

The most important feature of your son’s new Libre, is the arrow. Yes, the number value is important, but the arrow which indicates the rate and direction of his BGL change tells shows most important information. And of course, look back at the tots showing recent history of his glucose levels. Couple this with Joe’s information about the lag - blood sugar will reflect more current information - if the meter is accurate.
I personally notice a big difference when I go “low” and drink a glass of juice to bring me up; after a few minutes [maybe 20 minutes] my CGM will still be giving the same, or lower, glucose level but I can feel myself going up and the meter will reflect that the juice is doing its job.

Thank you so much for the replies. I guess I’m a little paranoid about it all. (When aren’t we?) We also love with my mom who is, for unknown reasons, a little upset about the change. Since finances are ALWAYS tight around here it seems, she thinks I will be spending more money on supplies to poke his fingers AND scan him. She thinks it’s a waste and asked me just when do I plan on depending on just the scanner (so he isn’t poked as often, you must if you feel “off” or if the monitor itself indicates, I know that much at least, lol)? It’s kind of frustrating.

I’m always convinced I am doing something wrong and am always on pins and needles when he goes to the dr every three months. Yet she says he’s one of her best patients. Feels good for 5 minutes, then I am back to “I don’t know what I’m doing, what if I screw up?” I have many fears when it comes to him it seems.

Sorry this reply got long. I don’t get to talk to other adults very often. :blush:

Jennifer, I feel you, what you are enduring. Yes, he is your treasure and you have the burning desire of motherhood to protect and nourish him.
You could tell your mother that in time [my guess a month or less], you will be able to trust his Freestyle and will be doing less ans less finger pokes - not more than two per day. In looking at “independent” testing reports, it appears to me that the Freestyle Libre 14 day sensor is one of the most accurate devices when measured against Lab Test Blood Sugar - not against the less reliable BG Meter.
I do not use the Freestyle, but may I suggest that if you have the ability to upload hid Libra data to an app [I know there is an app available for doctors] you may be able to look as his BGL trends and compare those graph lines to the finger-sticks you are doing; you may find his sensors make perfect sense over a few hour period. I’m pulling for you.

Dennis, as always thank you so much. I wish I had more people like you around me. Small town living doesn’t always have its perks. :grin:

We will continue to monitor the trends and watch the arrows as you’ve said for a while longer. His school nurse is like a second mom and she has become almost as intuitive as I have and has pulled him out of class early to test him. I’m glad I have her on our team but she’s learning just as much as I am about new devices and such. So…this isn’t easy. But we are trying and I guess that’s all we can do as parents right? Do our best as much as we know how.

I am so glad we have you in the community Dennis. Thank you again.

Thank you Jennifer for your very kind words - I enjoy my time here and love the support offered by so many people - and I continue to learn more and more every week.
It must feel having the school nurse who is so supportive; I met my first fellow T1D after I had diabetes for about 20 years. She was a high school student who baby sat our kids - yes, she taught me a few things, like she was the first person to suggest that I inject insulin in my abdomen. I had mostly used my legs that had turned to leather wit scar tissue.

Oh my, we had to stop using his abdomen after the first 6 months as he was getting the fatty pockets around it. We once used the backs of his arms until I accidentally bruised him badly one night. He jerked his arm back (sound asleep) as I was going in and it stayed a beastly round purple spot for a good year or so. Plus it had this bump to it. Oh I felt so bad then. But the dr said it happens and there was nothing to worry about and it would clear up on its own. It took another year for the bump to go away. Now, you can’t even tell he had something like that on his arm.

So, we give his shots in his legs. Rotating for breakfast lunch dinner and bedtime. Sometimes he feels it, most of the time he doesn’t. I used to hate giving him his shots. Especially when he was a year old. Now, I kind of laugh about it when other people go Oh My Goodness. I also use it when my two younger had to get their shots, I would tell them, if Bubba can do this many many times in a day, then we can do just one, okay? It would help them and they would fear their shots less. Now, they (mostly) don’t care.

Today was a better Libre day. Readings were a bit closer. I do believe if we can wait it out a bit longer and continue to watch the trends, we can stop poking as much. :grin:

I read on Reddit that the Libre gives you the average results of the last 15 minutes of your glucose. People mentioned they read this in the manual in case your interested. :slight_smile:

@Lakuma, the Freestyle readers I’ve held in my hand give actual present-time BGL [Body Glucose Level] with an arrow showing direction of change, if any. The reader shows, if my recollection is correct, actual graphs of historic BGL readings for periods up to eight hours.

We’ve been using the Libre since diagnosis two months ago. We don’t trust it too much; if it reads below 100 or over 200 we check his finger. It’s a helpful tool, but like all technology, has its limits.

Hi All,

I am using the Libre after trying the Dexcom and really prefer it. I do notice that some sensors are more accurate that others. When I spoke with someone from their tech department, she mentioned that some people feel one arm is more accurate than the other, which I am finding as well. Plus, don’t forget that the first day or so is much less accurate, and after that the readings will be more in line with your finger stick. They are rarely super close, but close enough that I find it very helpful.

Re: where to inject insulin. I have been doing butt and thighs, and occasionally stomach. A REALLY don’t want to develop scar tissue or fat deposits, so other that rotating, any suggestions would be welcome. I don’t have a ton of fat on my stomach, but certainly enough to “pinch and inch”.


Hey everyone, I have come across information that wasn’t given to us (by the dr) as well. I had to find out from a friend who also uses the Libre. It was suggested to poke his finger and continue to monitor his levels both with the Libre and finger pokes. However, it was not told to us to use the Libre to, as he said, “calibrate” his readings better. Which means the dr did not also write out a script for the strips for the Libre. We’ve been using the Relion meter we have to compare the readings.

When I got the Libre, I did read that it could be used to do the finger pokes. As I said though, the dr did not tell us nor did she write out the script to go along with the reader and the sensor. So, I will be emailing the dr on Monday to see if we can get one (crossing fingers for insurance not to have a fit). Like I mentioned before, even though it has been 9 years for my son, I feel as though I know nothing.

I do need to ask as well, do you use your Libre to test yourself when it comes to poking your finger? Or do you use another meter? Could that be why I am getting such large gaps in his readings? The past two days have been fairly closer in gaps thankfully. I am ready to rely on the Libre, it has been seemingly far more accurate when he has felt low, while the blood meter has been 20+ what he’s feeling. However, his Nana (who we have lived with since before diagnosis) isn’t.

Thank you to everyone who has responded so far. I am grateful to have this community to talk to.

Hi Jennifer,

I use the Libre test strips only in the first day or so of a new sensor. I use my One Touch Verio the rest of the time. The reason is this: The finger stick readings from the two are VERY similar. The reason I use the Libre strips at all is because if I think I have a bad sensor (has happened once) and I call the company, they want to know what the Libre finger stick says in comparison to the Libre reader (because they want to make sure my Verio isn’t off base). If the values are significantly discrepant between the Libre finger stick and the Libre CGM, they will send you a new sensor. Don’t forget that the first day is doesn’t work as well, and after that it should be closer to the finger stick. Another reason I just use my verio is that the Libre sticks don’t come with a way to prick your finger, so I have to have my Verio with my anyway.

Hope this helps.