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Type 2 Freestyle libre sensor.

D

Debstoller

Member
Messages
9
Type of diabetes
Type 1
Treatment type
Insulin
Can anyone help? I started to use a freestyle libre sensor yesterday. Paired with my I phone. I turned my phone on approximately 10.30 this morning. When I first scanned my sensor at 1pm it said my blood sugar was approx 3 at 9am this morning. My phone was turned off at this time and I didn’t feel low when I got up. Is this reading incorrect? IMG_1685969693.083135.jpg
 
Chances are if you were still in bed it was a compression low, ie you were lying on the sensor so it reports a false low. But to prove this you need your phone turned on and alarms enabled, then you can check at the time with your blood glucose meter. Having said that it can be seen on the graph that your glucose levels were falling quickly and if you were up and about it might be correct. At this level though I would always double check with a meter as I find my sensors under record at low levels, and over record at high levels.

to get a continuous line on the graph and full stats you also need to scan at least once every 8 hours.
 
LIbre (and other CGMs) are wonderful pieces of kit but only if you understand their limitations.
Was your low a true low? I don't know and you will only know if you took a finger prick at the same time.
However,
- we often find the first 24 to 48 hours after inserting a sensor, the readings can be erratic. This is why many of us apply the sensor 24 to 48 hours before activating it.
- sensors are designed to be most accurate at "normal" levels. Therefore, it is alway recommended to check high (usually above 8 or 9) and lows (under 4) with a finger prick.
- if pressure is applied to a sensor it will report a false low. This most commonly occurs at night if you lie on your sensor. You can usually spot these "compression lows" because the graph only drops for one or two readings and then shoot back up again. (I do not see that happening on your graph so this unlikely to be the cause.)

Did you know that the sensor only stores the last 8 hours of data. If you do not scan every 8 hours, you will see gaps as you do in your graphs.
 
This used to happen to me sometimes and I worked out that it was because I was either leaning on it during my sleep (placed it awkwardly on my back arm) or if I was in the sea (too cold so the sensor dropped). Could it be something like that?
 
I just don’t understand how my phone read my sensor when the phone was off? I didn’t turn the phone on until gone half 10 so it certainly wasn’t connected to wifi. When I first scanned the sensor my blood sugar was 7.2 and all I had had is a couple of cups of tea.
 
Debstoller said:
I just don’t understand how my phone read my sensor when the phone was off? I didn’t turn the phone on until gone half 10 so it certainly wasn’t connected to wifi. When I first scanned the sensor my blood sugar was 7.2 and all I had had is a couple of cups of tea.
Click to expand...
Your phone is not reading your sensor when it is off.
When you scan your sensor, you download the last 8 hours of data from your sensor.
The data you can see on the graph were from the scan you did at 12:30.
 
Initially I only had my phone to start and scan with. At first this was great as I simply put my phone into Do Not Disturb overnight, but allowing notifications from the Libre app. Worked perfectly. That was until my phone did an update and the alarms no longer worked. Abbott sent me a reader and I now start my sensors with the reader and use the alarms, especially overnight. I still scan with my phone when I wake up during the night. This keeps the data up to date. When going to bed of of night a night I simply go into sound settings and reduce all volume levels to nil.
 
Oh I see so the sensor stores the data? I didn’t realise that. In which case I may have been lying on it at 9am as was still in bed. That makes more sense. I will scan as soon as I get up tomorrow morning and not wait like I did today till just before I eat. So used to finger pricking prior to meals!! Thanks all for your help.
 
I have experienced false lows usually within 20 minutes of going to bed. I check beforehand and assuming it is between 6-8 I'll go to bed. Almost every night I get a low alarm within 20 minutes. I usually lie on my right side and the sensor is on the back of my left arm, so not sure it is compression. I get up and do a finger test and usually similar to before I went to bed. I've got that frustrated with it, I end up disabling the alarms completely, which is a shame.
 
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