How much time do you spend having low blood sugar (<4mmol/L)?

[aseriesofunfortunateevents]

Hey,

I try to maintain a very tight control of my blood sugar, and this results in my libre 2 reporting that i spend 10% of time below 4mmol.

Now, generally that time will be in the high 3s. Rarely do I have a blood sugar that needs more than ~4g of fast acting carbs to correct. I also check my blood sugar regularly and don't inject within 3hrs of sleeping.

I also think that my libre2 can on occasion report a blood sugar far lower then it actually is (confirmed with finger prick), and that can skew my time in range.

However, when I see my diabetic nurse, they will tell me that i have too many hypos. I personally would prefer having a fairly regular minor hypo to having a high a1c. My last a1c was 5%.

I know there is some research suggesting that hypos can contribute to dementia. And a bad hypos can kill you. I appreciate that, that is why i don't inject before sleeping and check my levels regularly.

Is 10% of time below 4mmol very bad? Overall my TIR is ~90% because im basically never above 9mmol.

(I saw recently there was a thread around a1cs that are too low, but my question is more around whether my TIR is bad).

Thanks

 

[Jaylee]

Hi,

When I get hypos with the libre.
I check against the meter & log “the meter says.”
Especially when it looks like the hypo lasted 45 minutes with the lag on the sensor?

How far below “4.0” did you go…?

 

[Westley]

I'm also interested in this.
I think in the USA and other countries that use mg/DL, 70 is often considered the threshold, which is just below 3.9, so already a little lower than we get told in the UK.

Treating the hypo threshold number as a fixed value for everyone seems a bit strange to me anyway.
When I'm keeping tight control, I feel good and completely unimpaired at numbers that would have made me feel shaky sweaty and confused back in the early days when I was used to running a lot higher most of the time.

 

[Antje77]

I also think that my libre2 can on occasion report a blood sugar far lower then it actually is (confirmed with finger prick), and that can skew my time in range.

Is 10% of time below 4mmol very bad? Overall my TIR is ~90% because im basically never above 9mmol.

If the time below range is 10% according to Libre, but you've confirmed with fingerpricks that Libre reads lower than blood, you didn't actually spend 10% below range. If this is the case it's not bad of course.

Your numbers sound similar to mine, and my Libre tends to read too low.
I use DiaBox in addition to the LibreLink app, mainly because you can calibrate DiaBox.

Coincidentally I spent my last week a bit lower than usual (surprising decrease of insulin needs), and I made screenshots of my TIR on both apps to show my endo at my next visit, to make her aware that not all is what it seems on Libre.
The difference between Librelink and calibrated Diabox is only about 1mmol/l, but the difference between time below range on both apps are huge: 45% low on Librelink, 100% TIR on Diabox over 7 days.
So this is what can happen if you're cruising in the 4's and Libre reads a tad low. There were no lows, or only very short ones.

The picture happened at an unusual time, I tend to be in the 5s, 6s and 7s a lot more usually (my hba1c is higher than yours), so the effect is pretty exaggerated, but it does happen.

However, when I see my diabetic nurse, they will tell me that i have too many hypos.

I'm very happy I'm not obliged to share my Libre data for exactly this reason.
When I see my endo I show her the data from Diabox on my phone, and once I've proven my Libre reads lower by doing a fingerprick right then and there. She accepts the calibrated numbers.

Feel free to use my screenshot to show your diabetes nurse how this works.

 

[Antje77]

(Screenshot posted separately, the forum software didn't accept the post with the pic.)

 

[aseriesofunfortunateevents]

If the time below range is 10% according to Libre, but you've confirmed with fingerpricks that Libre reads lower than blood, you didn't actually spend 10% below range. If this is the case it's not bad of course.

Your numbers sound similar to mine, and my Libre tends to read too low.
I use DiaBox in addition to the LibreLink app, mainly because you can calibrate DiaBox.

Coincidentally I spent my last week a bit lower than usual (surprising decrease of insulin needs), and I made screenshots of my TIR on both apps to show my endo at my next visit, to make her aware that not all is what it seems on Libre.
The difference between Librelink and calibrated Diabox is only about 1mmol/l, but the difference between time below range on both apps are huge: 45% low on Librelink, 100% TIR on Diabox over 7 days.
So this is what can happen if you're cruising in the 4's and Libre reads a tad low. There were no lows, or only very short ones.

The picture happened at an unusual time, I tend to be in the 5s, 6s and 7s a lot more usually (my hba1c is higher than yours), so the effect is pretty exaggerated, but it does happen.




I'm very happy I'm not obliged to share my Libre data for exactly this reason.
When I see my endo I show her the data from Diabox on my phone, and once I've proven my Libre reads lower by doing a fingerprick right then and there. She accepts the calibrated numbers.

Feel free to use my screenshot to show your diabetes nurse how this works.

Thanks for that.

Yeah sometimes my libre will be reporting 3.2 mmol when a finger prick will show 4.0mmol. In my experience this usually happens a lot for specific sensors. For other sensors it will be a lot more accurate. But a bad sensor can distort my TIR and then ill get a dressing down from the nurse.

The solution would be to replace the sensor but it happened very recently when I was on holiday. I bring spare sensors but im more conservative with their use when im away.

 

[ElenaP]

(Screenshot posted separately, the forum software didn't accept the post with the pic.)

View attachment 63901

What a good idea take screenshots to consultation! I will start doing that.

 

[Ushthetaff]

before Libre I was regularly below 4 , nowadays I am lucky ( or unlucky depending on your point of view) if I’m below 4 once a month This down to the alarms on the Libre system , I set my low alarm at 4.1 as soon as it alarms I take some quick acting sugar ( wee can of “ full fat” Cola )

 

[jaywak]

before Libre I was regularly below 4 , nowadays I am lucky ( or unlucky depending on your point of view) if I’m below 4 once a month This down to the alarms on the Libre system , I set my low alarm at 4.1 as soon as it alarms I take some quick acting sugar ( wee can of “ full fat” Cola )

How soon after you've had the bleep at 4.1 and your can of coke does your Libre show a rise ? I have set mine at 4.5 but after having a spoonful of glucose or jelly babies it can still show a drop to 3.8 or even lower before I see a rise .

 

[Antje77]

What a good idea take screenshots to consultation! I will start doing that.

My hospital offers a messaging system where you can send a message to whoever you like. It'll be read by assistants first, I think, to decide if it needs sent on to the specialist.
A couple of times I've had very specific questions and I expected them to be complicated enough for my endo to not have a ready answer.
So I sent a message telling her what I would be asking with links to articles relating to this a couple of weeks beforehand, so she could think about it or look things up before the actual appointment.
I even included a link to a thread on here where I asked the same questions in preparation of my appointment, and included a greeting to her on that thread in case she'd read it.
Worked wonders, she was prepared for my questions, and told me being addressed on that thread made her laugh! https://www.diabetes.co.uk/forum/threads/adding-metformin-to-insulin.184734/post-2451741

 

[Jaylee]

How soon after you've had the bleep at 4.1 and your can of coke does your Libre show a rise ? I have set mine at 4.5 but after having a spoonful of glucose or jelly babies it can still show a drop to 3.8 or even lower before I see a rise .

Hi,
My way of doing it..

Before Libre. (“BL”) testing in quick succession saw a drop further before a rise.
I personally put the Libre or Diabox alarm on “snooze” for 45 minutes, & go by the meter after confirming & treating. Then Test again another 20 minutes later…

 

[Antje77]

How soon after you've had the bleep at 4.1 and your can of coke does your Libre show a rise ? I have set mine at 4.5 but after having a spoonful of glucose or jelly babies it can still show a drop to 3.8 or even lower before I see a rise .

I second @Jaylee , while a fingerprick usually shows a rise withing 10 minutes after treating, my Libre can lag behind over 30 minutes after a low.
To my thinking, glucose would be sent to where it's needed firs (brain, organs), and the interstitial fluid in the back of my arm is very low on the list of priorities.
No idea if I'm thinking correctly here though.

 

[Jaylee]

I second @Jaylee , while a fingerprick usually shows a rise withing 10 minutes after treating, my Libre can lag behind over 30 minutes after a low.
To my thinking, glucose would be sent to where it's needed firs (brain, organs), and the interstitial fluid in the back of my arm is very low on the list of priorities.
No idea if I'm thinking correctly here though.

I’m convinced interstitial fluid is at the back of “the queue” when refuelling from a low. (From the non related stuff I read.)
The brain takes priority.

For me on average with the libre. It takes 40 minutes to “recover.” (The meter a good 30 minutes prior.)

I’ve been T1 for over 47 years. Used the “force” in my childhood then my first meter in the late 1980s.
I still feel “I’m back in the zone” before my meter… Driving? Go by the meter.
Lol, I rarely get hypos driving. Stress dumps glycogen…

 

[jaywak]

I second @Jaylee , while a fingerprick usually shows a rise withing 10 minutes after treating, my Libre can lag behind over 30 minutes after a low.
To my thinking, glucose would be sent to where it's needed firs (brain, organs), and the interstitial fluid in the back of my arm is very low on the list of priorities.
No idea if I'm thinking correctly here though.

Can I ask you how low yours reads before you see a rise ?

 

[RoughcutAU]

Like alot of people I find the CGMs tend to report lower numbers when low and higher numbers when high. In range (I set mine from 4.0-8.0) it seems reasonably accurate aside from the odd sensor. When sensor reports low (high 3s)i just keep an eye on myself and fingerprick if I feel off. Usually high 3 on sensor will Fingerprick at least 1mmol higher. I try to leave notes on the app so the Endo/Nurse can see the difference.

Atm my TBR for last 90 days is showing at 6% which im sure my team will have issues until i explain the difference all over again.

I do find it interesting that on all my tests that the reference ranges for BGL bottom out at 3.00mmol and even my Endo admits that its not uncommon for non diabetics to be in the 3s and function normally. Its more those being treated with BGL lowering medications (insulin etc) that the “4 is the floor rule” came about.

 

[Antje77]

Can I ask you how low yours reads before you see a rise ?

It usually drops a bit further on the graph first, like you said. I guess this has to do with the algorithm predicting current BG rather than showing what it measures at that moment.

 

[Westley]

What I still want to know is how low does it have to be to be harmful in itself.

So not just because it might go lower in the short term, or might reduce warning signs and cause it to go lower at some point in the future - at what level does some form of damage occur due to the level at that moment?

 

[Ushthetaff]

How soon after you've had the bleep at 4.1 and your can of coke does your Libre show a rise ? I have set mine at 4.5 but after having a spoonful of glucose or jelly babies it can still show a drop to 3.8 or even lower before I see a rise .

I normally take a reading about 10 mins after it normally shows a 0.1 rise after that I just have a biscuit and result is I don’t go hypo ,

 

[jonathan183]

what level is harmful in itself ... the short answer is we don't know

 

[Antje77]

What I still want to know is how low does it have to be to be harmful in itself.

So not just because it might go lower in the short term, or might reduce warning signs and cause it to go lower at some point in the future - at what level does some form of damage occur due to the level at that moment?

What a good question!

I think (but I'm no scientist) it's a very hard question to answer though.
There are lows so severe that they lead to immediate brain damage (and death), but I think those are not the lows you're wondering about.

I've read that it's thought that multiple episodes of low BG throughout the years can cause some brain damage. I'm pretty sure it's not the mid to high 3's doing this, considering non diabetics tend to go this low occasionally.
Now lower 3's and high 2's? Who knows?

Mild brain damage due to hypos seems very hard to measure if you ask me. Tiny alterations in the brain aren't easily found, and lots of things outside diabetes can cause them too.
Even if you had a huge cohort of diabetics and non diabetics to compare over decades, you'd still need CGM data over decades as well to even find a correlation to hypos. And we don't have CGM data for that long, let alone a huge cohort of people regularly doing tests to see how their brain function changes over the years.

For myself, I don't worry too much about the higher 3's, although I treat when under 4 to nudge me up a little, but I very seriously try to avoid getting close to 3.0.