Fingerprick reading below 3.9 yet no hypo symptoms?

[BenjaminRWT]

This is a new one to me. Yet another first, I suppose.

I put in a new Libre sensor this evening. A little later than usual, because for reasons I don't want to go into, I was late leaving work today.

So I got home and had dinner. My new sensor wasn't quite ready, so I felt it wise to take a fingerprick test before I ate, so I'd see how I was doing.

3.7.

Now, I know that would be low enough to cause a hypo. Yet I felt fine, in that I didn't have any symptoms of a hypo. I've only had maybe 2 to my knowledge so far - one was very brief and I was unable to do a fingerprick to confirm it. Second one I felt, the libre was reading 4.1 but fingerprick said 3.8 - close enough, definitely a hypo - enough to know how they feel. Like I say, nothing indicating a hypo.

I decided to have my dinner, and test again in 15 minutes, when I was due to do my Lantus injection.

I did this, by which time my Libre sensor was ready. It was giving me a reading of 6.2, and my follow-up blood test read 4.5 mmol/L.

Now, I'm well aware Libres aren't accurate - I've seen enough discrepancies between the two to know that. But is it possible that blood tests can be wrong? Or did I somehow not notice?

Needless to say I'm a little confused here. I've settled into accepting the Libre as a means of identifying trends, rather than a fully accurate indication of my blood glucose levels, and if I think I'm still a bit high a while after eating, I like to confirm where I'm at with fingerpricks.

Of late, my last few Libres tend to read higher than fingerpricks, although sometimes they're close (I consider a difference of around 0.5 to be "close enough).

Apologies for a long rambling post, but for a fingerprick to read that low with no hypo symptoms isn't something I've encountered before. It's got me wondering now.

 

[Tdm]

The fingerprick may have been wrong (eg you didn't dry your hands well, the strip may have been old/damaged which can results in a low reading)
Or you may lack hypo awareness. This website says 25% of diabetics do. I don't have hypo awareness, or you can become temporarily unaware if you have been running low.
Or it may just have been diabetes throwing a curveball.

 

[rebrascora]

Can I ask which test strips you use?
The reason I ask is that I use Caresens Pro but I also have some Optium which can be used in my Libre reader. What I find is that if I compare all 3 systems, my Caresens can read 4.5, Libre might say 3.8 and the Optium test strip is usually lower at maybe 3.5. I have been using my Caresens as my official BG meter for 4 years and I trust it and I know that Libre sensor reads slightly lower than it most of the time but I expected the Optium test strips to be somewhere in between, not lower. Personally I don't trust the Optium test strips.
I can usually feel hypos in the low 4s but occasionally I will get down to mid-high 3s before I feel one. Sometimes it depends how fast my levels are dropping or what I am doing as to when I will feel it and it is not totally consistent. Very occasionally I have had the sort of situation you describe and then 5 mins later it has hit me. I have quite a lot of hypos and I am very confident treating them so I don't panic at all when I have one so that doesn't explain that it might be panic causing the delayed sensation, just sometimes our bodies are more alert to it than others and of course out BG meters are not anywhere near as accurate as the decimal place suggests. If you were getting down to low 3s and not feeling it on a regular basis, I would start to be concerned about your hypo awareness but for an odd occasion to see mid to high 3s is not anything to be overly concerned about although I would likely do a retest straight away to double check.

 

[BenjaminRWT]

Can I ask which test strips you use?
The reason I ask is that I use Caresens Pro but I also have some Optium which can be used in my Libre reader. What I find is that if I compare all 3 systems, my Caresens can read 4.5, Libre might say 3.8 and the Optium test strip is usually lower at maybe 3.5. I have been using my Caresens as my official BG meter for 4 years and I trust it and I know that Libre sensor reads slightly lower than it most of the time but I expected the Optium test strips to be somewhere in between, not lower. Personally I don't trust the Optium test strips.
I can usually feel hypos in the low 4s but occasionally I will get down to mid-high 3s before I feel one. Sometimes it depends how fast my levels are dropping or what I am doing as to when I will feel it and it is not totally consistent. Very occasionally I have had the sort of situation you describe and then 5 mins later it has hit me. I have quite a lot of hypos and I am very confident treating them so I don't panic at all when I have one so that doesn't explain that it might be panic causing the delayed sensation, just sometimes our bodies are more alert to it than others and of course out BG meters are not anywhere near as accurate as the decimal place suggests. If you were getting down to low 3s and not feeling it on a regular basis, I would start to be concerned about your hypo awareness but for an odd occasion to see mid to high 3s is not anything to be overly concerned about although I would likely do a retest straight away to double check.

I'm using a 4sure smart duo. I was provided with one when I was diagnosed. I actually lost my original one recently, and because the diabetic department at the hospital that has been dealing with me didn't get back to me, I took the liberty of simply buying a new one - I still get the strips on prescription, that's why I've stuck to it - I can also use it to test for ketones if needed. I get those strips on prescription as well, although I've only needed to use them a couple of times. My levels haven't got that high since the early days of my diagnosis. Very worst has been high 10s or 11s on the libre for a little while.

If the readings are off, usually the libre reads higher than the strips, as much as 2.0 mmol/L higher on occasion.

The 3.7 could have been a one-off and something was skewing the reading (@Tdm's suggestion of a possible dodgy strip or not having dried my hands properly for example). I was going to be doing my injection about 15 minutes later, so I thought that would be a good time to retest. 4.5 is still on the lower end of the range anyway - most mornings I read about 5.5 on my Libre, give or take when I wake up, or just when my levels come back down after I've eaten.

I've had fingerprick readings of low 4s plenty of times. Typically I might have something to eat just in case, if I'm not actually already planning to eat, just in case.

To read that low without symptoms was what's thrown me this evening.

 

[everydayupsanddowns]

Did you double-check the 3.7 reading at the time with another strip @BenjaminRWT ?

Test strips can have some variation within the ISO standard they a
l have to meet, and all meter handbooks stress that if a reading doesn’t match how you are feeling you should recheck with a fresh strip.

I checked and had an unexpected 12.7 last night when I was looking to see if my CGM was tracking OK, as it had wobbled earlier. I was grumbling to myself and about to whack in a suggestion, when I thought it was odd to have risen so much with no real reason, and I knew I hadn’t washed my hands (so lazy, so foolish!).

When I rechecked it was 7.2 - which was in line with my CGM and with how I was feeling. So glad I didn’t dose the correction before I rechecked!

 

[everydayupsanddowns]

To read that low without symptoms was what's thrown me this evening

It is possible to develop impaired awareness of hypoglycaemia with increased exposure to hypoglycaemia - but it doesn’t sound as if you have had lots of readings below 4.0 over months or years?

 

[BenjaminRWT]

It is possible to develop impaired awareness of hypoglycaemia with increased exposure to hypoglycaemia - but it doesn’t sound as if you have had lots of readings below 4.0 over months or years?

Nothing that's been anything to worry about

Most of the low readings have been on my libre and mostly a result of my laying on it awkwardly as I sleep. It sets off the alarm at something like 2am, I make my way downstairs to do a fingerprick and what was a 3.7 ends up being more like 5.5 when I fingerprick. Sometimes the libre graph starts righting itself before I've even had a chance to sit down and fingerprick! I've got into the habit of doing fingerpricks everytime it goes low anyway. I'm used to doing it.

I was only diagnosed in March of this year, so this is still new to me. Plenty of firsts!

 

[rebrascora]

Nothing that's been anything to worry about

Most of the low readings have been on my libre and mostly a result of my laying on it awkwardly as I sleep. It sets off the alarm at something like 2am, I make my way downstairs to do a fingerprick and what was a 3.7 ends up being more like 5.5 when I fingerprick. Sometimes the libre graph starts righting itself before I've even had a chance to sit down and fingerprick! I've got into the habit of doing fingerpricks everytime it goes low anyway. I'm used to doing it.

I was only diagnosed in March of this year, so this is still new to me. Plenty of firsts!

Can I suggest that you take your test kit to bed with you. If you do end up actually hypo in the night it is not a good idea to be negotiating the stairs to use it when half asleep and hypo. I am hoping/assuming you have hypo treatments by the bed.

In fact it is also a good idea to have a spare BG meter. If you ring up the manufacturer and explain you lost yours (don't have to say you bought a new one), they may well offer to send you a replacement. The manufacturers make their money from the test strips so it is in their interests to make sure you have one of their meters. This is why the reps often supply them free to the diabetes clinics.

 

[BenjaminRWT]

My hypo treatments go where I go. If I'm out of the house, I keep a tube of Lift tablets in my pocket, and if I'm at home I keep them within reach. They're in my pocket, and some orange juice cartons in my bag, too. Just in case.

I keep my BG meter in my work bag, in the event I need to fingerprick in work - it's happened, so it's good to confirm if I need to be treating it. I should look into a 2nd meter for reasons you brought up, actually. That was something I hadn't considered.

 

[everydayupsanddowns]

I should look into a 2nd meter for reasons you brought up, actually. That was something I hadn't considered.

I have 3 handsets that all take the same strips. One upstairs, one on the kitchen table, and one in the car in case don’t take one out with me and my CGM plays up.

 

[trophywench]

I had 2 spare meters and only last week Tuesday daughter No 1 found one we'd both utterly forgotten about secreted right at the back of their bathroom cupboard - she had to clear everything out as they had a pretty torrential and disastrous burst hot pipe whilst they were both at work on Monday so anyway, she opened the zip on the outer fabric case, drenched her front and it would have been submerged for some hours by then so it was binned. Doesn't tend to do anything electronic much good, does it, water. Dunno about the other one, clearly I must have put it somewhere safe ..... And their house had 5 industrial dehumidifiers plugged in by the firm their insurers sent them on the Tuesday. Loss Adjusters reckon it could take several months to dry out properly ...... the first lot are coming to have another look the week after next to better assess whether all the furniture needs more than temporary off site secure dry storage ....... and see how much good the dehumidifiers have done so far, which ceilings need to be replaced, walls replastered, blah blah .....

 

[Leadinglights]

I had 2 spare meters and only last week Tuesday daughter No 1 found one we'd both utterly forgotten about secreted right at the back of their bathroom cupboard - she had to clear everything out as they had a pretty torrential and disastrous burst hot pipe whilst they were both at work on Monday so anyway, she opened the zip on the outer fabric case, drenched her front and it would have been submerged for some hours by then so it was binned. Doesn't tend to do anything electronic much good, does it, water. Dunno about the other one, clearly I must have put it somewhere safe ..... And their house had 5 industrial dehumidifiers plugged in by the firm their insurers sent them on the Tuesday. Loss Adjusters reckon it could take several months to dry out properly ...... the first lot are coming to have another look the week after next to better assess whether all the furniture needs more than temporary off site secure dry storage ....... and see how much good the dehumidifiers have done so far, which ceilings need to be replaced, walls replastered, blah blah .....

We went through that same scenario a year ago and it did take a long time for it to dry out. The dehumidifiers, industrial ones do use a lot of electricity so a good idea to estimate the increase in the bill as we managed to get compensation for the extra we used.
We were getting 2 black buckets per day of water for weeks. It really only started to dry properly once the plaster was taken off the stair wall which is the one where the leak had occurred.
Ours was caused by a blocked overflow from a header tank when the ball cock failed.