Libre targets.

[Zinadane]

Hi,
2.5 weeks into my new life as a T1d libre user. Wow, what a game changer!
45 years T1d BTW.
Estimated A1c is 6.0; historically I was always mid to high 6’s. It has enabled me to make a big improvement to BG levels. I just wish I could have had it 4 years ago or whenever it came out.

I’ve just had my telephone consultation with the specialist. She was telling me about time in target values, where guidelines are min 70% within 3.9-10 and no more than 5% at less than 3.9. Well, I have 83% for the 3.9-10 range which is decent, but she was very concerned about my 9% time in the less than 3.9 range. I tried to explain that sometimes if I am 3.7 and it is not falling then I am not desperate to act, she did not seem to agree. So, I am wondering what other people’s thoughts are on the less than 5% time in the below 3.9 range, especially if you’re hovering in the 3.6-3.8 range?

 

[Rokaab]

If I'm at lower than 4 I'll be eating something sugary
Though note when showing under 5 the libre can be incredibly inaccurate and really does need a blood test check

 

[urbanracer]

Hi,
2.5 weeks into my new life as a T1d libre user. Wow, what a game changer!
45 years T1d BTW.
Estimated A1c is 6.0; historically I was always mid to high 6’s. It has enabled me to make a big improvement to BG levels. I just wish I could have had it 4 years ago or whenever it came out.

I’ve just had my telephone consultation with the specialist. She was telling me about time in target values, where guidelines are min 70% within 3.9-10 and no more than 5% at less than 3.9. Well, I have 83% for the 3.9-10 range which is decent, but she was very concerned about my 9% time in the less than 3.9 range. I tried to explain that sometimes if I am 3.7 and it is not falling then I am not desperate to act, she did not seem to agree. So, I am wondering what other people’s thoughts are on the less than 5% time in the below 3.9 range, especially if you’re hovering in the 3.6-3.8 range?

The Libre is known to go low when you lay on it, even though your blood glucose levels are normal. So the first question would be - when are your lows happening? If they are mainly overnight then I'd be less worried than constantly going low when awake.

Its accuracy at the top and bottom ends of the spectrum are also sometimes questionable so are you doing a finger prick test to verify/calibrate the Libre?

 

[In Response]

New If I'm at lower than 4 I'll be eating something sugary

Completely agree and, given the Libre is 15 minutes behind "real" values, I would definitely be eating something sugary as my blood sugars may have already fallen further

 

[ROE100]

Hi

I have used the Libre and found it useful to a degree but as someone has suggested you must check with a finger to make sure the readings of the Libre are close to actual. I was constantly more than 2 units more than Libre so reviewing the data with a HCP became complicated to explain as they wanted me to treat the low while I wasn't actually low I was in the 5's/6's. I did go through a long process with Abbott checking this checking that and changing sensors etc but they concluded Libre was not for me.

However if my finger confirmed I was in a high 3 / low 4's I would eat something but not a lot as I can be on the lowish side and only need to eat 5/10 carbs to get back into the 7's/8's while anymore will spring above the 10's and stay in the 10's for some time. but sometimes I need to lot more than 5/10 carbs. T1 for 33+ years

Roe.

 

[Zinadane]

The Libre is known to go low when you lay on it, even though your blood glucose levels are normal. So the first question would be - when are your lows happening? If they are mainly overnight then I'd be less worried than constantly going low when awake.

Its accuracy at the top and bottom ends of the spectrum are also sometimes questionable so are you doing a finger prick test to verify/calibrate the Libre?

Well tbh I haven't done many comparison finger test. It's been so nice to give my fingers a rest after years of stabbing them! I understand the 15 min delay and potential descrepances. I'm comfortable at 3.7 for example and if the trend is not downward I tend not to act. Obviously depends on what I'm doing, ie i wouldn't set of driving at this level.

 

[Zinadane]

Hi

I have used the Libre and found it useful to a degree but as someone has suggested you must check with a finger to make sure the readings of the Libre are close to actual. I was constantly more than 2 units more than Libre so reviewing the data with a HCP became complicated to explain as they wanted me to treat the low while I wasn't actually low I was in the 5's/6's. I did go through a long process with Abbott checking this checking that and changing sensors etc but they concluded Libre was not for me.

However if my finger confirmed I was in a high 3 / low 4's I would eat something but not a lot as I can be on the lowish side and only need to eat 5/10 carbs to get back into the 7's/8's while anymore will spring above the 10's and stay in the 10's for some time. but sometimes I need to lot more than 5/10 carbs. T1 for 33+ years

Roe.

Agree, 10grams to bump it up, otherwise it becomes a frustrating proces of bouncing high low back and forth. Things always depend on what my activities will be of the coming hours.

 

[Maco]

Just something to think about for you guys, I was one of the first people to be placed on Libre trials In my clinic. When I first started using it I was highly addicted & my control became really good, the only problem I was having was that Libre kept showing me to be under 4.0 when I was actually still around the 5mmol mark. I remember going for a check up with my consultant and only talking my Libre with me & not my blood testing machine, he looked at the results and instantly said “you’ve lost hypo awareness’ I went on to explain that when the Libre was reading low I was actually a fair bit higher but I had no evidence to back it up. He recorded on my file I had lost hypo Awareness & informed me he was going to contact dvla.

Luckily the consultant I saw that day wasnt the guy I normally see, so soon as I left the clinic I managed to get a phone call with him. Arranged to go straight back down the hospital immediately & get things put right. Realistically I could of lost my license that day.


If you feel the Libre is constantly reading you lower than you are make sure you blood test to back it up. That would be my advice

 

[Zinadane]

Blimey, very interesting information!
It becomes a very complicated and grey area when you have 24/7 bg data on an electronic database accessed by your consultant.
God help us if dvla would have access to it.
Again, nearly 3 weeks in, I love my libre, so much better control for me.

 

[Maco]

Blimey, very interesting information!
It becomes a very complicated and grey area when you have 24/7 bg data on an electronic database accessed by your consultant.
God help us if dvla would have access to it.
Again, nearly 3 weeks in, I love my libre, so much better control for me.

It can be a brilliant piece of kit, just make sure to do the blood test to double check. I’ve just scanned before bed and it said 17.2, I thought it seemed funny as I don’t feel high at all. Did a finger prick test and I was 10.0, imagine I’d took say 5 units of novorapid to correct a result of 17? I’d of gone severely hypo

 

[Ushthetaff]

Hmmm consultants and blood sugar ranges the life long problem , if your Libre is showing 4.1 then in my experience your actual bs is probably a little over 5 , my DSN wants range between 4 & 7 it’s not happening as long as mine are between 5 and 9 I’m happy so is my diabetic consultant , I’ve spent years with bloods way over 12 hence only one leg , in recent times since my bs are “ under control “ I’ve had some serious cuts etc and they have healed really quickly normally a good sign of blood sugar levels being ok , have to agree though the Libre is a definite game changer for me , as I’ve said many a time if I had it 10 years ago I’d still be walking round on 2 legs , but I’m not complaining I can do a great pirate impersonation lol .

 

[Zinadane]

Anyone clued up on how the libre trend arrow is calculated.
I get a flat arrow and an hour later i'm up 3 or 4 mmol/L.
Whats the algorithm used to decide on the arrow given?

 

[ROE100]

Snap also had this experience. Did chat to Abbott about it but they were a bit dismissive. Sorry I can't assit in your question.

 

[sgm14]

Anyone clued up on how the libre trend arrow is calculated.
I get a flat arrow and an hour later i'm up 3 or 4 mmol/L.
Whats the algorithm used to decide on the arrow given?

From https://www.librelinkup.com/articles/glucose-readings

A rise of 0.05 per minute is flat, but that is 3 units over the hour. It is also possible that when you do a scan, your figures are only rising slowly, but when you are not looking they are rising faster.

 

[Zinadane]

So I wonder over what time period the values are being looked at in order to establish the trend arrow?

 

[Zinadane]

I've found this info:

· The libre will record a reading every minute. When you scan your phone, the reading you get is based on these 1 minute readings.

· Every 15mins, it will store a reading for a longer period (8hrs). This is what the graph is based on.

· The arrow is based on the data between the last ‘stored’ reading (that happens every 15mins), and the current reading, but it has an algorithm that weights the calculation more heavily on the more recent minute readings – and this will decide the trend arrow.

· For example, if you scan 12mins after the previous ‘stored’ 15min reading, the arrow will be calculated based on the previous 12 mins of glucose levels, with a weighting towards the more recent readings.

So potentially it is making a judgement over up to 15mins which seems ok.
But on the other hand it may be making the judgement only over the last minute which doesn't seem so clever.
Can anybody clarify?

 

[sgm14]

So I wonder over what time period the values are being looked at in order to establish the trend arrow?

Don't have any proof, but I would suspect it is just looking at the last minute.

My reasoning is that when I have taken some glucose to correct a low, or to avoid a low, it is not uncommon for me to scan within a few minutes of each other and the trend arrow can change quickly. That's not conclusive, but if it was looking at the figures over a longer period, I would expect the trend arrow would not change so quickly.

 

[sgm14]

The arrow is based on the data between the last ‘stored’ reading (that happens every 15mins), and the current reading, but it has an algorithm that weights the calculation more heavily on the more recent minute readings – and this will decide the trend arrow.

Guess that means I was wrong!

So potentially it is making a judgement over up to 15mins which seems ok.
But on the other hand it may be making the judgement only over the last minute which doesn't seem so clever.
Can anybody clarify?

Whether it is clever or not probably depends on why you are looking at the trend arrow. In my situation where I am looking to see if I have taken enough glucose to counteract or avoid a low, what has happened in the last few minutes is much more important than what happened in the last 15 minutes.

 

[Zinadane]

Don't forget 15min lag as measurement is from Interstitial fluid.

 

[sgm14]

Don't forget 15min lag as measurement is from Interstitial fluid.

The lag is not 15 minutes for everyone.
I seem to be one of the lucky ones with a delay of only 5 minutes. And I hear the new Freestyle libre 2 has an even shorter delay.