Sensor Too Cold - / - Driving

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Val1133

Val1133

Well-Known Member
Relationship to Diabetes
Type 1
I was out on my bike today and got caught in the rain cycling home. I paused close to home to check my Libre 2 reading and got the following error message. 'The Sensor is too cold to give glucose readings. Please try again in a few minutes' 😳 I didn't even know this was a thing! I was wearing a T-shirt and the sensor on my upper arm was exposed to the elements. Perhaps I will need to get something to protect it in future :confused:

I had to continue on my way in the hope that my levels weren't too low - and had a couple of sweets just in case. The sensor started working again as soon as I got home and was reading 4.1 and going down rapidly😱 This was backed up by finger prick.

To make matters worse, I was to go out again to meet up with a friend - a 20 mile drive away. I had a high glucose snack and delayed my departure by 45 minutes. BG rose nicely and I was on my way.

How do you all manage your BG levels for driving? I feel I am between a rock and a hard place, trying to keep my BG levels within range (and ideally below 8) and trying to keep them above 5.0 so I can drive. My levels are all over the place. Just before driving home, my Libre 2 was reading 7.8, so I was OK to drive. However, on my drive, I noticed the reading going down to 5.1, so I found a place to stop the car and did a did a finger prick which also showed 5.1. I had a few dextrose tablets and fruit sweets to bring the levels up and continued my journey. I noticed the CGM going down to 4.9 then 4.8, but then it started to go up again to 5.0 and 5.1. By the time I got home, it had risen to between 6 and 7 🙂

It just seems to be a constant battle which I always think I'm losing.😳
 
Val1133 said:
I had to continue on my way in the hope that my levels weren't too low
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Why didn’t you have a fingerprick machine with you? It’s important to always carry it, it’s the law to carry it when driving and it’s really important to carry it when exercising as you can’t rely on a sensor for times when bg is changing quickly or when you might have a hypo eg during exercise.

For driving I just follow the rules, I regularly do long drives. I test before setting off, with a sensor but fingerprick if in any doubt. Then I stop and check at least every 2 hours and any time an alarm tells me it could be dropping or when I feel it may be dropping to recheck.
 
Lucyr said:
Why didn’t you have a fingerprick machine with you?
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I had forgotten it this morning - left it on the bedside cabinet 😳 but I did have it when I was driving this afternoon.

I wonder if the CGM going below 5.0 mid drive would cause an issue? I mean, it could happen when there isn't anywhere suitable to pull over. My journey wasn't that long, so I would have thought 7.8 would have been good to go.
 
Where I need to leave home to drive somewhere at a specific time, I set an alarm for 1 hour before departure time to ensure I sort any issues and avoid a hypo since I don’t want to have to delay leaving.

Before driving if I am 5 and dropping I will eat something. 5 and level or rising I don’t need to eat.
Before setting off I ensure JBs are easily accessed next to me. I also have my test kit with me in case I don’t feel the same as my sensor is showing.

I still have had times when I have got caught with a hypo when out and have then had to ask OH to come and collect me and the car if necessary, otherwise it is just wait it out for at least 45 minutes.

In spite of all my precautions I did get caught with a hypo on a motorway, so had to pull over. Very scary but I was rescued and my car taken off the motorway so that I was able to wait it out in a lay-by rather than waiting on the motorway and then having to rejoin the fast traffic.

I would certainly never chance driving without waiting the required time. You will not be insured if you do, so you did the sensible thing in waiting. It is frustrating at times but necessary precautions. I am sure that most of us have forgotten to take our kit out with us, and good that you had your test kit when you drove.
 
Val1133 said:
I had forgotten it this morning - left it on the bedside cabinet 😳 but I did have it when I was driving this afternoon.

I wonder if the CGM going below 5.0 mid drive would cause an issue? I mean, it could happen when there isn't anywhere suitable to pull over. My journey wasn't that long, so I would have thought 7.8 would have been good to go.
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It’s fine to drive below 5 so long as you’re above 4 and have had a snack.

If you’re in the 4s before driving have a snack but don’t need to wait 45 minutes

If you’re in the 4s during driving (hopefully you’re not touching a phone or watch to find that out) stop as soon as safely possible to have a snack. Again you don’t need to wait 45 minutes unless you’ve dropped below 4.

If you drop below 4 confirm with fingerprick, treat the hypo, then wait 45 minutes from the point that your bg reached 4+. If you still don’t feel safe to drive then wait longer.
 
It is OK to drive when your levels are between 4 and 5 provided you have eaten some carbs to bring it up. It is only once you drop below 4 that you are grounded so to speak until 45mins after your levels come up above 4.

Sounds like you managed it all really well. but yes, when you need to drive somewhere you do need to keep a close eye on your levels an hour in advance of starting the drive. Your bike ride will continue to drop your levels for up to 48hours afterwards, so that will be why your levels were dropping significantly whilst you were driving. It is why some of us reduce our basal insulin dose when we know we are going to exercise.

Yes, it is the button batteries in the sensor I believe which cause them not to function when they get cold. If you have warm hands, just holding your hand over the sensor for 30 seconds should bring it back to life. I have had it happen plenty of times when I have been out with bare arms in the autumn and winter but I don't think it has happened in the summer for me. Thankfully I always have warm hands so I can quickly warm it up to get a reading. What I find most frustrating is that my BG meter suffers from the cold summer and winter and I have to either take the batteries out and warm them in my hands or put the meter down my bra for a few minutes to get it to work. Obviously you can't do that with the sensor when it is stuck to your arm, but the warmth from my hands seems to sort it far quicker than my BG meter.
 
Hi Val,
For me I’m happy with a BG between 5 and 10 for driving, especially as Libre includes 10 as within range
 
I try to be in the 6s or 7s to drive. I just like that buffer. For long drives, I try to make sure I don’t have any bolus onboard, or, if that’s not possible, I sometimes reduce my bolus. I always fingerprick before driving even though my Dexcom is very accurate.

If you’re trying to stay below 8 all the time, you’ll probably making things harder. The Libre says 70% TIR is very good control, and that range is 3.9 to 10.
 
Lucyr said:
Why didn’t you have a fingerprick machine with you? It’s important to always carry it, it’s the law to carry it when driving and it’s really important to carry it when exercising as you can’t rely on a sensor for times when bg is changing quickly or when you might have a hypo eg during exercise.
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It's not particularly convenient when cycling, neither needing to pack it somewhere nor trying to do a test (especially if it's cold and or wet). With that said if I'm going to be out all day I will tend to take it with me just in case (assuming I remember).

Driving any particular distance straight after injecting/eating is a pain as you never know quite whether you got the combo right, I also have to drive to drop my children off at school in the morning which is a faff as I get dawn phenomenon and so need to take extra insulin to cover that. I now tend to eat (and dose for) my breakfast after I drop them so I can reduce the quantity of insulin I have on board. I also have food in the car of course.

Thankfully these days I don't usually need to drive long distances for work (meetings for example), but when I did in the past I would accept that I'd run high and then take a correction dose en-route if I stopped, or try to sort it out once I arrived (which is also difficult as it's not very useful to go low during a meeting if you get the correction wrong).

Thank goodness most meetings are done remotely over Teams/Zoom these days, makes life much easier!
 
SB2015 said:
In spite of all my precautions I did get caught with a hypo on a motorway, so had to pull over. Very scary but I was rescued and my car taken off the motorway so that I was able to wait it out in a lay-by rather than waiting on the motorway and then having to rejoin the fast traffic.
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Oh! That sounds scary 😱
 
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