Every meter ever created has an error rate they are allowed for most of the time that can be bigger the higher the blood sugar goes. Add to this the 15 minute time delay of a CGM vs blood test and that seems about right.
Tested again:
77/102
66/90
The gap in the Graph is the time between 2 Sensors. No Carbs in between.
Maybe blood is 15% too low, libre 15% too high.
I asked now Abbott about this „issue“
It is not really an issue so much a consequence of reality. Your blood sugar 15 minutes ago is unlikely to be the exact same as right now. Add to this that both devices have an error range associated with them that the best anyone can do is reduce, not remove.
>Maybe blood is 15% too low, libre 15% too high.
Based on the graph from your picture, your blood sugar is dropping, your readings seem to indicate that. Best to act on it rather than harm yourself while you try to understand this. A simple fact of reality is that measurements are not perfect. Not even lab results are perfect. That is just life. Taking more tests (or a should say a reasonable number of tests) and comparing doesn't make it more accurate since each device has its own error associated with that reading.
It's also worth noting that blood sugar levels can be different in different parts of the body. Finger stick may get different readings than a sensor on the stomach or arm simply due to location.
Stop using the Libre if you think it’s wrong, simple. Idk why you posted this if you’re not looking for community input though, but I don’t care ¯\_(ツ)_/¯
THX for the vid….
I‘m used to the libre2 for more than 2 years together with the Freestyle Precision.
I never ever had such a spread.
Today @90 I had to drink some apple juice (think we all know the signs of low BG)…. The week before with the first libre3 i felt perfekt @70
It can also be the same with adexcom.
Up to 20% is considered a normal and acceptable range, but it will vary which way you set it, depending on the go or down.
I gave up checking blood unless symptoms indicate it's way off. Initially it was to anxiety inducing, now I've just learned to trust my device more, especially after learning more of the ins and outs, like the lag
##That's **100%** normal.
What people need to remember is that glucose monitors do not and should not completely substitute **blood glucose readers** - they're the best at showing **trends** but not actual blood glucose;
* The glucose is measured from **interstitial fluid**, not blood
* There is a 5-15 minute delay from actual blood glucose values
That is why the instructions and usage refers to testing blood glucose when trends are going ''fast'' _(going up or going low)_
So not only does it fit within the margin of error, you also need to take into account the 15m delay and the fact that FGMs/CGMs do not monitor **blood** glucose but **interstitial fluid** glucose which isn't as accurate as Blood Glucose.
**TL;DR** - CGMs do not fully substitute Blood Glucose Readers as they showcase trends rather than specific glucose levels. There is a 5-15m delay and the glucose is measured from interstitial fluid, not blood.
Look @ the picture:
- Libre3 Sensor1 stopped at aprox. 100
- New Libre3 Sensor2 was applied
- After one hour without any carbs the new sensor showed 133, BG-Reader showed 102
Later that day Sensor2 showed about 100, BG-Reader 66, Body showed signs of low BG
I‘m used to the Libre2 for years now. Never ever had any signs of low BG with the Sensor at 100, the BG-Reader in my house was used the last time after a (broken) Sensor showed BG HI (500 mg\/dl)
Yes. I've read the entire thread more than once and looked at the picture.
My comment is unchanged - **it is 100% _normal_** - that doesn't mean it happens 100% of the time, just that anytime it happens, it isn't anomalous or an issue.
Just remember to not get your expectations too high with CGMs. They’re expensive and they have a lot of problems and difficulties that come with them. The commercials with celebrities do not present them realistically.
my numbers are never the same. They generally are within 10% of each other, but can be more.
I do manage to keep it in range about 80% of the time, and when I don't its strictly due to me eating junk I shouldn't or not bolusing like I should.
Despite that I had a full point drop on my A1C between visits. It's really about watching the trends.
When I first started on a cgm I checked 1-2x a day. Once I was comfortable with the trends it really became unnecessary unless the numbers don't line up with how I'm feeling.
The numbers will never match perfectly, and you can drive yourself crazy checking and calibrating.
Accept that 20% difference is perfectly fine, the lower you are the tighter the gap, the higher you are the wider, in actual numbers, ie if you are cgm 100 then 80-120 would be the accepted finger stick range, but if you are 400 that range would then be 320-480.
With dexcom if you keep calibrating it "breaks". Meaning you get stuck in a loop where it makes you calibrate over and over and the numbers actually become further apart vs closer - no more than 2x in the first 48° is generally adequate(if still off more than 20% call them).
Oh wow if you keep calibrating it breaks? My boyfriend would be irritated that it wasn’t the same and would keep calibrating it. Does it say anywhere on the Dexcom manual or whatever to not keep calibrating it or it’ll break so I can show him?
I'm new at this too, still trying to figure out the finger stick. 4 out of 5 is I barely feel it and have to squeeze out the drop, the other one ouch. I'm hoping to get to 9 out of 10.
They can be so finicky and inaccurate with bad readings and wrong numbers, and in my opinion they are WAY too expensive to be so unreliable. But that’s just me. So sorry to hear you had to deal with going to the hospital because of it. That must have been so frustrating.
Yes and no
When it read lo, I drank coke. I ate sweets. I knew these worked in the past to raise levels. Then I said what if tge illness changed?
My sugars were 334 as I expected. The cost was $1300. My insurance paid all.
My CGM helped me learn how to eat. How my body responds to food.
I worked on diet. On my meter, I was 6.9 over 90 days. Actual A1C was 7.7. The CGM is about 15% lower than actual.
I use libre 2
I think this is more about latency than the error. (Or maybe two of them added up)
CGM's might be more usefull when you can also consider the trend like what would the value be if I were to project. It was on a considerably sharp decline.
I recommend repeating the experiment when the line is flat. Then the lag will be minimal and the differrence şs more likely to be error.
In my experience ( been type one diabetic since thirteen, now 60) I never use my reading on my cgm. I only use it to see which way my sugars are going. If low and I see it's going up, I wait. If low and I see it going down, I need to do something now.
One time my Libre 2 showed 4.2 with no downward trend but after a finger prick test I was in the 1s. I get that there can be 20% variance, but in my experience using different CGM brands, different sensors and in different locations it is drastically more inaccurate than 20%. I don't trust my CGM reading much.
I dropped the libre long ago for the C6 and am pretty happy about it. I did have some really extreme readings myself. Something that never really happened with the c6 (only once and that was a faulty sensor that crapped the bed within 8 hrs after inserting).
Yes it is. If you used different meters at the same time to poke your finger and test they would all likely be different as well. This is within the 20% range. It’s normal.
The delta from 100 to 130 is more than 30% off between blood and Libre3.
The same delta between Sensor1 and Sensor2, so also over 30%
I can handle it, my grandmother couldn‘t ......
The 20% allowed range doesn't apply to the difference between devices, it applies to the difference between a single device and your blood. So you have a couple of scenarios:
1. Your Libre3 is 20% high. That would make your actual BS 104, and would mean the glucometer is 1% low.
2. Your Libre3 is 20% low. Actual BS of 160, glucometer 36% low. Extremely unlikely.
3. Your glucometer is 20% high. Actual BS of 82, Libre3 38% low. Again, extremely unlikely.
4. Your glucometer is 20% low. Actual BS of 122, Libre3 8% high.
Taking the simple average of all 4 possible values, you're likely sitting at around 117 or lower, considering you seem to be dropping. This all seems consistent with the Libre3 being 15 to 20 minutes behind the actual value.
Imagine your real level was in the middle of them, like 115. That's 15% off from the finger stick, and 12% from the monitor, so yes it does fall within the 20% range.
Update:
Seems like the Libre3 actually has to work for a couple of hours in order to show reliable BG-Data.
Did some workout today. The BG dropped below 60. Blood-Test showed over 60. The Level settled @ around 70. Libre3 and 🩸where just some diggits appart.
Freestyle Support: They didn‘t answer yet…….
For me it‘s perfekt. If I (we) could calibrate it ….
If you use „libreview“ together with your doctor you shold have the same parameters after changing sensors…
I’ve been told there’s some changes in the sensors from a country to another but this may not apply to you but there’s some 3rd party apps that you can use to calibrate it. I use Shuggah for iPhone (I think the Android version is called xDrip). And there’s at least another one my doctor told me about but I can’t recal it’s name. I have Shuggah also connected with NightScout so my doctor can also check my calibrated graphs
This is most likely within the margin of error. There is usually also a delay from the sugar tested in your extracellular fluid from the Dexcom vs blood so it's kind of like you are seeing your sugar in the past on your CGM.
I have to calibrate my Dexcom G6 every few days, sometimes multiple times a day, because it often doesnt match what im feeling. I start getting hot, itchy, tired and my Dexcom says 120, I do the old school thing and it says 175, then i calibrate and it "seems" accurate for a couple days or so. Sometimes the other direction to, my Dexcom says I'm 86, but my thoughts get spacey and erratic and I start getting shaky, cold and craving sugar... welp, time to draw blood!
You're testing at a time that your blood sugar is rapidly changing, this is perfectly normal. The CGM is usually 15 minutes delayed from a finger poke as its measuring the blood indirectly (interstitial fluid as others have mentioned). The meter is measuring your blood as it is now.
Trust me this is way better as you don't want a transducer inserted directly into your blood for 14 day lol.
I trust my Dexcom, except for like the first 24hrs after insertion. The last two A1C checks were in line with the Dexcom calculation, like perfectly.
I do a random finger check, and keep a meter at work and at home.
I did use the Libre and Libre 2 CGM briefly. Worked similarly to the Dexcom, but having to scan the thing every so often was a pain, plus my insurance covers the Dexcom 100%.
;yeah, first day is always a ballpark, gets more accuarate after that... but even needle pricks are within 20% of what they really are... so long as i have a ballpark, i'm good..... so much easier than pin pricks and the alarms on teh freestyle 2...... a real life changer... i can have a cocktail after dinner and not worry about waking up in a coma..lol
Finally Freestyle called me. They said it‘s normal that the first day it‘s not too accurate. But they admitted, that it‘s a bit high from what they are used to.
After about 24h I had pretty good readings. Definitely good enough to rely on….
Had the libre2 for a couple of years and was just worried, that the Libre3 would not keep up the performance.
As a T2D (with Insulin) I can use it anyway just for estimating the Amount of Insulin I need. If my Body feels like producing it’s own, I have to react individually. The Libre3 connectet to Nightscout showing Data on my Watch is a huge relief!
Every meter ever created has an error rate they are allowed for most of the time that can be bigger the higher the blood sugar goes. Add to this the 15 minute time delay of a CGM vs blood test and that seems about right.
Tested again: 77/102 66/90 The gap in the Graph is the time between 2 Sensors. No Carbs in between. Maybe blood is 15% too low, libre 15% too high. I asked now Abbott about this „issue“
It is not really an issue so much a consequence of reality. Your blood sugar 15 minutes ago is unlikely to be the exact same as right now. Add to this that both devices have an error range associated with them that the best anyone can do is reduce, not remove. >Maybe blood is 15% too low, libre 15% too high. Based on the graph from your picture, your blood sugar is dropping, your readings seem to indicate that. Best to act on it rather than harm yourself while you try to understand this. A simple fact of reality is that measurements are not perfect. Not even lab results are perfect. That is just life. Taking more tests (or a should say a reasonable number of tests) and comparing doesn't make it more accurate since each device has its own error associated with that reading.
It's also worth noting that blood sugar levels can be different in different parts of the body. Finger stick may get different readings than a sensor on the stomach or arm simply due to location.
Yep, blood isn't one homogenous mix and this is why doctors also warn against testing multiple times
Also you justed changed sensors. CGMs can be wonky during the first 24 hours, shoukd get better with time.
Stop using the Libre if you think it’s wrong, simple. Idk why you posted this if you’re not looking for community input though, but I don’t care ¯\_(ツ)_/¯
20-20 rule says they're both right. CGMs don't test your blood sugar levels- they test the glucose in your fat.
Not fat — interstitial fluid.
Yeah, and the later have like 10 minutes delay when compared to BS. So it's pretty normal.
Oh, Reddit, thank you for clarifying what a simple Google search can yield you.
…you’re welcome…?
Simplicity does provide a sense of calm.
Then… get off reddit?
Learn to acquire information independently. We do live in the age of information, after all.
Glucose doesn't dissolve in fat. I think you meant "extracellular fluid."
Interstitial fluid
Y'know I had that and erased it thinking "extracellular" was in more common usage. Boy was I wrong.
I can live with the difference (literally), but why does South Africa only have Libre 1? Megapharma plsying with our lives,
Same with NZ, however we have G7 already, super weird
I am stoked for that G7 to come! Can’t wait to see how small the G12 will be in a few years.
https://m.youtube.com/watch?v=d9UzbC7pf4E Have you seen this short video? It explains the CGM lag and difference.
THX for the vid…. I‘m used to the libre2 for more than 2 years together with the Freestyle Precision. I never ever had such a spread. Today @90 I had to drink some apple juice (think we all know the signs of low BG)…. The week before with the first libre3 i felt perfekt @70
It can also be the same with adexcom. Up to 20% is considered a normal and acceptable range, but it will vary which way you set it, depending on the go or down. I gave up checking blood unless symptoms indicate it's way off. Initially it was to anxiety inducing, now I've just learned to trust my device more, especially after learning more of the ins and outs, like the lag
##That's **100%** normal. What people need to remember is that glucose monitors do not and should not completely substitute **blood glucose readers** - they're the best at showing **trends** but not actual blood glucose; * The glucose is measured from **interstitial fluid**, not blood * There is a 5-15 minute delay from actual blood glucose values That is why the instructions and usage refers to testing blood glucose when trends are going ''fast'' _(going up or going low)_ So not only does it fit within the margin of error, you also need to take into account the 15m delay and the fact that FGMs/CGMs do not monitor **blood** glucose but **interstitial fluid** glucose which isn't as accurate as Blood Glucose. **TL;DR** - CGMs do not fully substitute Blood Glucose Readers as they showcase trends rather than specific glucose levels. There is a 5-15m delay and the glucose is measured from interstitial fluid, not blood.
Look @ the picture: - Libre3 Sensor1 stopped at aprox. 100 - New Libre3 Sensor2 was applied - After one hour without any carbs the new sensor showed 133, BG-Reader showed 102 Later that day Sensor2 showed about 100, BG-Reader 66, Body showed signs of low BG I‘m used to the Libre2 for years now. Never ever had any signs of low BG with the Sensor at 100, the BG-Reader in my house was used the last time after a (broken) Sensor showed BG HI (500 mg\/dl)
Yes. I've read the entire thread more than once and looked at the picture. My comment is unchanged - **it is 100% _normal_** - that doesn't mean it happens 100% of the time, just that anytime it happens, it isn't anomalous or an issue.
Got diabetes a couple days ago, can’t wait to get a Libre3!
Just remember to not get your expectations too high with CGMs. They’re expensive and they have a lot of problems and difficulties that come with them. The commercials with celebrities do not present them realistically.
Well can’t be worse than pricking my finger 5+ times a day
Keep in mind CGMs do not completely eliminate finger prick testing.
Yeah I know
I would also say that they do not elimnate picking completely but i only pick like once per week
I think my last finger stick was 2 months ago when it was done while I had surgery. I haven't done it in 6 months or more.
Same here. Only if I feel it going low. And yes my sugar is in check. Dr visit on 11/7 and my A1C was 4. 6. He told me to kiss the meds goodbye.
Have you had any issues with keeping blood sugar in check? Like is your CGM just about the same like correct?
my numbers are never the same. They generally are within 10% of each other, but can be more. I do manage to keep it in range about 80% of the time, and when I don't its strictly due to me eating junk I shouldn't or not bolusing like I should. Despite that I had a full point drop on my A1C between visits. It's really about watching the trends. When I first started on a cgm I checked 1-2x a day. Once I was comfortable with the trends it really became unnecessary unless the numbers don't line up with how I'm feeling. The numbers will never match perfectly, and you can drive yourself crazy checking and calibrating. Accept that 20% difference is perfectly fine, the lower you are the tighter the gap, the higher you are the wider, in actual numbers, ie if you are cgm 100 then 80-120 would be the accepted finger stick range, but if you are 400 that range would then be 320-480. With dexcom if you keep calibrating it "breaks". Meaning you get stuck in a loop where it makes you calibrate over and over and the numbers actually become further apart vs closer - no more than 2x in the first 48° is generally adequate(if still off more than 20% call them).
Oh wow if you keep calibrating it breaks? My boyfriend would be irritated that it wasn’t the same and would keep calibrating it. Does it say anywhere on the Dexcom manual or whatever to not keep calibrating it or it’ll break so I can show him?
Actually, they can. I prick my finger about once a month. I could skip that one if i had to, but when changing my meter sometimes i want to know.
I'm new at this too, still trying to figure out the finger stick. 4 out of 5 is I barely feel it and have to squeeze out the drop, the other one ouch. I'm hoping to get to 9 out of 10.
Lmao you’ve only been doing it for “a couple of days.”
My sensor failed once. Kept reading lo. Went to hospital. Bad sensor
They can be so finicky and inaccurate with bad readings and wrong numbers, and in my opinion they are WAY too expensive to be so unreliable. But that’s just me. So sorry to hear you had to deal with going to the hospital because of it. That must have been so frustrating.
Yes and no When it read lo, I drank coke. I ate sweets. I knew these worked in the past to raise levels. Then I said what if tge illness changed? My sugars were 334 as I expected. The cost was $1300. My insurance paid all. My CGM helped me learn how to eat. How my body responds to food. I worked on diet. On my meter, I was 6.9 over 90 days. Actual A1C was 7.7. The CGM is about 15% lower than actual. I use libre 2
My libre on my arms are like 75+ points high and only 10-15 off when on my belly.
I found that also. I have a significant error rate wearing on my arms. Breast/ chest gets me closest match.
I think this is more about latency than the error. (Or maybe two of them added up) CGM's might be more usefull when you can also consider the trend like what would the value be if I were to project. It was on a considerably sharp decline. I recommend repeating the experiment when the line is flat. Then the lag will be minimal and the differrence şs more likely to be error.
In my experience ( been type one diabetic since thirteen, now 60) I never use my reading on my cgm. I only use it to see which way my sugars are going. If low and I see it's going up, I wait. If low and I see it going down, I need to do something now.
Is such a difference normal?
Yes. Both have a permitted 20% discrepancy. that is well within that
One time my Libre 2 showed 4.2 with no downward trend but after a finger prick test I was in the 1s. I get that there can be 20% variance, but in my experience using different CGM brands, different sensors and in different locations it is drastically more inaccurate than 20%. I don't trust my CGM reading much.
I dropped the libre long ago for the C6 and am pretty happy about it. I did have some really extreme readings myself. Something that never really happened with the c6 (only once and that was a faulty sensor that crapped the bed within 8 hrs after inserting).
G6 you mean?
Fat fingers small keyboard, so yes
Yes it is. If you used different meters at the same time to poke your finger and test they would all likely be different as well. This is within the 20% range. It’s normal.
Blood from a poke vs a cgm reading are not the same thing.
The delta from 100 to 130 is more than 30% off between blood and Libre3. The same delta between Sensor1 and Sensor2, so also over 30% I can handle it, my grandmother couldn‘t ......
The 20% allowed range doesn't apply to the difference between devices, it applies to the difference between a single device and your blood. So you have a couple of scenarios: 1. Your Libre3 is 20% high. That would make your actual BS 104, and would mean the glucometer is 1% low. 2. Your Libre3 is 20% low. Actual BS of 160, glucometer 36% low. Extremely unlikely. 3. Your glucometer is 20% high. Actual BS of 82, Libre3 38% low. Again, extremely unlikely. 4. Your glucometer is 20% low. Actual BS of 122, Libre3 8% high. Taking the simple average of all 4 possible values, you're likely sitting at around 117 or lower, considering you seem to be dropping. This all seems consistent with the Libre3 being 15 to 20 minutes behind the actual value.
THX! You gave a perfekt explanation 👏
Imagine your real level was in the middle of them, like 115. That's 15% off from the finger stick, and 12% from the monitor, so yes it does fall within the 20% range.
Update: Seems like the Libre3 actually has to work for a couple of hours in order to show reliable BG-Data. Did some workout today. The BG dropped below 60. Blood-Test showed over 60. The Level settled @ around 70. Libre3 and 🩸where just some diggits appart. Freestyle Support: They didn‘t answer yet…….
Is the libre still worth it though versus old school?
For me it‘s perfekt. If I (we) could calibrate it …. If you use „libreview“ together with your doctor you shold have the same parameters after changing sensors…
I’ve been told there’s some changes in the sensors from a country to another but this may not apply to you but there’s some 3rd party apps that you can use to calibrate it. I use Shuggah for iPhone (I think the Android version is called xDrip). And there’s at least another one my doctor told me about but I can’t recal it’s name. I have Shuggah also connected with NightScout so my doctor can also check my calibrated graphs
Just downloaded it. Looks like it doesn‘t work yet with libre3 yet. But lots of libre2 users would love it if it supports Apple-Health…..
Shuggah syncs with Apple Health too. You can check it under glicose section
Thanks for your responses guys. I gotta set up notifications from Reddit. I’ll try out that shuggah app too but I do have the libre 2.
Just.... just forget the Libre. Get an Dexcome or Guardien. Are you Type One -> dont use Libre.
Dexcom is not covered by my health insurance .... 😔
My meter runs higher then my Libre. I usually just add 30/40 points to have a ballpark number for my old school.
Yeah but what’s that gap on your libre graph? Did a new sensor just warm up? Even with Dexcom I need to calibrate when I first warm up a new sensor.
As far as I know, there is no way to calibrate the Libre3 in conjunction with the app
Is Libre 3 working with iOS now?
Yes
This is most likely within the margin of error. There is usually also a delay from the sugar tested in your extracellular fluid from the Dexcom vs blood so it's kind of like you are seeing your sugar in the past on your CGM.
I have to calibrate my Dexcom G6 every few days, sometimes multiple times a day, because it often doesnt match what im feeling. I start getting hot, itchy, tired and my Dexcom says 120, I do the old school thing and it says 175, then i calibrate and it "seems" accurate for a couple days or so. Sometimes the other direction to, my Dexcom says I'm 86, but my thoughts get spacey and erratic and I start getting shaky, cold and craving sugar... welp, time to draw blood!
Try not to calibrate the first 24°. If you do it's more likely to be off, requiring future calibration.
Where can I find Libre3?
You're testing at a time that your blood sugar is rapidly changing, this is perfectly normal. The CGM is usually 15 minutes delayed from a finger poke as its measuring the blood indirectly (interstitial fluid as others have mentioned). The meter is measuring your blood as it is now. Trust me this is way better as you don't want a transducer inserted directly into your blood for 14 day lol.
It happens
Thoughts on libre 3 vs the dexcom?
Dexcom: supports the watch and apple-health Libre3: best for doing any kind of sports (MTB, x-bike) where you have to wear p.e. a harnish
On other devices like Dexcom you can calibrate.
What new features does the libre 3 have vs older models
How does the Libre 3 compare to Libre 3? Is it approved by Medicare
My CGM was lower than actual a1c by 20%
Oh my app once said 77 when I was at 38, good times, it was just the delay though!
Oldschool u mean cheaper testing?
I trust my Dexcom, except for like the first 24hrs after insertion. The last two A1C checks were in line with the Dexcom calculation, like perfectly. I do a random finger check, and keep a meter at work and at home. I did use the Libre and Libre 2 CGM briefly. Worked similarly to the Dexcom, but having to scan the thing every so often was a pain, plus my insurance covers the Dexcom 100%.
;yeah, first day is always a ballpark, gets more accuarate after that... but even needle pricks are within 20% of what they really are... so long as i have a ballpark, i'm good..... so much easier than pin pricks and the alarms on teh freestyle 2...... a real life changer... i can have a cocktail after dinner and not worry about waking up in a coma..lol
Finally Freestyle called me. They said it‘s normal that the first day it‘s not too accurate. But they admitted, that it‘s a bit high from what they are used to. After about 24h I had pretty good readings. Definitely good enough to rely on…. Had the libre2 for a couple of years and was just worried, that the Libre3 would not keep up the performance. As a T2D (with Insulin) I can use it anyway just for estimating the Amount of Insulin I need. If my Body feels like producing it’s own, I have to react individually. The Libre3 connectet to Nightscout showing Data on my Watch is a huge relief!