Is my blood sugar really dropping?

[MarinaDE]

Hi all,

I have Type 1 diabetes, but my endo has prescribed a combination of long-acting insulin and Type 2 medication, with the hope the combination will preserve what pancreatic function I have left. Normally this combination works like a charm — I inject the long-acting insulin in the morning, take the pills, and then forget about everything. My blood sugar stays as steady as a rock, provided I don't eat white bread or cake etc.

This week, everything has gone to hell. My monitor (Libre 3) is constantly sending me an alarm, and says my blood sugar readings keep falling to extreme lows. I'm scared to go to sleep My partner is currently on the other side of the world, and he's ringing me several times a day to check that everything is OK (because he has the Libre 3 app on his phone and can see my blood sugar readings).

I am travelling at the moment and my eating has been more erratic than normal, but even so, I don't understand why I'm getting these dramatic lows. Could it just be a dodgy sensor? I changed the sensor a couple of days ago. Or is it a sign that the Type 1 'honeymoon' period is over?

The thing is, when my blood sugar fell the first time, I could feel it, because I got very shaky. Now my monitor says dangerously low blood sugar, but I feel normal.

Has anybody else had something like this happen?

Marina

 

[Bruce Stephens]

Could it just be a dodgy sensor?

Could be. What do test strips show?

 

[MarinaDE]

I actually haven't tested using the finger prick — I completely rely on the monitor. That's a good idea, though.

 

[rebrascora]

You must double check unusual reading with a finger prick. Libre is not 100% reliable and particularly if you have caught it recently and perhaps lifted it and then stuck it back down, the filament can kink and give you false lows, or could it be that you are lying on the sensor in your sleep and causing compression lows.... particularly if you are in a strange bed where perhaps you will toss and turn a little more?

Are you aware of the limitations of Libre and other CGM. There is a list here in this link...

CGM limitations and precautions

Moderator Note: This helpful reply was copied from another thread as it details some of the commonly experienced limitations of continuous glucose sensors. My blood sugar has been in perfect range for days now, but although I haven't changed anything, I'm starting to get very short periods of...

forum.diabetes.org.uk

I had it in my memory that you were Type 3c rather than Type 1. Taking Type 2 oral medication will not preserve your pancreas better than meal time/bolus insulin, if you are Type 1 or Type 3c. Yes, it may be easier for you to manage for the time being just taking basal and tablets but the only Type 2 med which will help to cover meals is the likes of Gliclazide which will put pressure on your pancreas to secrete more insulin..... That is of course my non medically trained opinion.

 

[Leadinglights]

I actually haven't tested using the finger prick — I completely rely on the monitor. That's a good idea, though.

I think the advice is to test with a finger prick when the sensor shows low levels or if it doesn't match how you feel.

 

[MarinaDE]

I think the advice is to test with a finger prick when the sensor shows low levels or if it doesn't match how you feel.

This is good to know. I have a monitor in my bathroom cabinet I will haul out when I get home... in 30 hours! I have a long haul flight in between and I'm dreading the alarms.

 

[rebrascora]

Can you post a screen shot showing one or more of these lows to see if we can spot an obvious issue. Compression lows often have a pattern where they dip and then come back up in a particular profile. Are you treating the lows with hypo treatments?
The guidance for hypos is to double check with a finger prick if you don't feel hypo, then only take hypo treatment if you are below 4 and have 15g fast acting carbs, wait 15 mins and then retest with another finger prick. Libre can take up to half an hour to register your levels coming back up because of the algorithm, so you should always check recovery after 15 mins with a finger prick, other wise you end up over treating hypos and end up on a BG roller coaster.

 

[MarinaDE]

I just did a screenshot of today's readings. As you can see, it doesn't show a hypo. But when it hit the low point, it told me it was REALLY low — 54 mg. My phone started sounding an alarm. But as you can see, the graph doesn't register that extreme low that supposedly happened around midday. (I treated it by eating a glucose tablet.)

 

[Leadinglights]

I just did a screenshot of today's readings. As you can see, it doesn't show a hypo. But when it hit the low point, it told me it was REALLY low — 54 mg. My phone started sounding an alarm. But as you can see, the graph doesn't register that extreme low that supposedly happened around midday.

What have you been told would be hypo as 54mg/dl converts to the units we use in the UK as 3mmol/l which would be hypo territory and should be checked with a finger prick. I am surprised you do not keep your monitor with you.

 

[MarinaDE]

What have you been told would be hypo as 54mg/dl converts to the units we use in the UK as 3mmol/l which would be hypo territory and should be checked with a finger prick. I am surprised you do not keep your monitor with you.

There are probably lots of things I should do, but this is all very new to me. I have had diabetic training, but I did it in a foreign language and probably missed things. Hence my questions here.

 

[rebrascora]

Libre often over exaggerates lows due to the algorithm, which extrapolates previous readings to get try to predict your current Blood Glucose reading. This is because Libre reads interstitial fluid which is about 10-15mins behind BG, so when you are dropping fast and then level out or go back up it predicts you will be lower than you actually are and then readjusts when it gets more data.
Out of curiosity, what is your Type 2 medication and when do you take it? That is a very steep drop from about 12mmols to about 4mmols and it looks genuine rather than a sensor error or failing sensor and I am assuming you would not have been lying on your sensor at that time of the day. Was that before lunch or after and had you done anything particularly exertive before hand?

 

[rebrascora]

It could be that there is life left in your pancreas and going high triggered it to kick out some insulin, especially if you are taking Gliclazide. It may be that the long acting insulin has given it a bit of a breather and it is having a bit of a revival. I would have expected you to feel a drop that far and fast even though you didn't completely drop into hypo. Not full hypo symptoms but I often get a slight rush or feel a bit hot when levels drop like that. Sometimes my stomach flips a little bit like going down in a lift. It can be quite subtle until you know what to look for, rather than full blown hypo which is difficult to ignore.

 

[rebrascora]

Just to clarify, that whilst a glucose tablet seems to have sorted that issue, a proper hypo treatment is 15g fast acting carbs which in the UK would be the equivalent of 4-5 glucose tablets or 3 Jelly Babies and as I said above, wait 15 mins and then retest with a finger prick to confirm you have recovered. If not, you have another 15g fast acting carbs and retest in another 15 mins with a finger prick. Never rely on Libre at this time because it will usually show that you are continuing to drop and you will be drawn into over treating.

 

[SimonP]

I sometimes get libre sensors that read much lower than reality, on the order of 3 mmol/l lower than my actual BG and sometimes even more than that. At that point they are irrecoverable even with calibration (XDrip+) so they go back for a replacement.

I also fell into the habit of relying on the libre and very rarely checking with a finger prick (if I wasn't high and I wasn't low there was no need, so I thought...). However, on one occasion I felt like I was low, but didn't have any "hard to do maths" double-check symptoms so I did a finger prick test to find that the libre was underreading by ~8mmol/l (so I'd potentially been running high for more than a week even though my display showed good values). I was so unsure (having run high for an extended period) as to what my actual blood glucose was based on how I felt that I even popped to the GP's surgery and asked them to do a blood test on me (which agreed with my meter). Even then I was quite reluctant to take insulin to bring my BG back into range because of how I felt.

Needless to say I wasn't best pleased with the libre and indeed with myself for not having checked, and since then do calibrations (via XDrip+) and also check at least one a day via a fingerprick. To be fair to the libre devices they are much much better now than they used to be, though I do find that if I have fast swings in BG level (e.g. mis-timing a bolus, or doing an overzealous preemptive hypo correction) the sensor now tends to go offline for 5min (showing a sensor error) and will then often come back online with a different offset (I have no numbers to hand to back this up, but from observation).

Good luck with the long haul flight back.

 

[trophywench]

Marina uses Libre 3 - and unknown animal to the vast bulk of users here in the UK as it's not generally available here, being more a 'proper' CGM than a 'flash' one like the Libre 2 which is well known in the UK.

 

[MarinaDE]

Libre often over exaggerates lows due to the algorithm, which extrapolates previous readings to get try to predict your current Blood Glucose reading. This is because Libre reads interstitial fluid which is about 10-15mins behind BG, so when you are dropping fast and then level out or go back up it predicts you will be lower than you actually are and then readjusts when it gets more data.
Out of curiosity, what is your Type 2 medication and when do you take it? That is a very steep drop from about 12mmols to about 4mmols and it looks genuine rather than a sensor error or failing sensor and I am assuming you would not have been lying on your sensor at that time of the day. Was that before lunch or after and had you done anything particularly exertive before hand?

I take everything when I get up. This morning I had a hotel breakfast in the US and it must have had way more sugar in it than I realised, as my blood sugar began to spike very fast. So I went for a long and vigorous walk, as I have learned it will bring down blood sugar. But it came down super fast today. Maybe it was related to what I ate.

I travel a lot for work and I find it a nightmare, because I can’t predict either what I am going to eat, or what’s in it.

 

[Proud to be erratic]

Hi Marina, I think you are doing amazingly well in the bigger scheme of things. Managing one's BG is sometimes, quite simply, er ... well .... not simple!

It took me a great deal of trial and learning to recognise when I'd over bolused, or over eaten and 4 years on I still sometimes get it a bit wrong - it's 3am here and I'm awake because I'm low and been woken by my alarm. I've had a couple of JBs, which normally gives me a decent reverse without being too aggressive but right now that isn't working. Right now I don't know what I misjudged yesterday evening and right now that doesn't matter one tiny jot: I was low, been woken up - I'm now 15 mins on and a bit lower at 4.1 (your 74) and I have to wait and see if I have actually caught the fall or still need more fast glucose. As I type this my alarm is panicking me and my brain is saying steady, wait a bit longer. My FP matches my sensor exactly so I'm resisting over responding - but it is frustrating and infuriating. My alarm is still sounding; I've now been awake for 30 mins and "leapt" back up by 0.1 to 4.2 (your 75.6) - so I think the fall has been caught and now must eat something lowish GI to consolidate the correction .... and wait a bit longer before posting this and going back to sleep (if I'm lucky). Just found a plain biscuit.

44 mins on and I'm now 4.6 (your 83) so I seem to have regained some control - for now.

Tomorrow morning I'll be tired and grumpy - I'm retired but must get up early for an appointment and a busy day; so no possibility of a lie-in. At some stage I'll briefly try to see what I misjudged yesterday evening but right now I can't spot anything unusual, so probably won't find anything in the morning. I do know I'm not wearing the wrong colour socks (don't need those in this bed) - so I can't even use that rationale to explain why tonight's low happened.

So please don't beat yourself up - diabetes is Complicated, Confusing and Contradictory. Regardless, right now, whether you are T3c or T1; at least you can learn and try to outwit your diabetes in time - after learning! It WILL get easier and more manageable in time and the hiccups will reduce and be less intrusive.

Meanwhile Good Luck and good night (or should that be good night and good luck; in German there will be a correct grammatical sequence, I think!).

PS, I have learnt (the hard way) to have a test meter handy at all times; getting a fp on a screen gives a sense of security when CGM is panicking me or just hassling me. I've got 3 meters: one generally in use, one in the car and one in my travel bag.

 

[Inka]

I actually haven't tested using the finger prick — I completely rely on the monitor. That's a good idea, though.

There’s your problem then! Lows should always be checked with a fingerprick, along with any ‘strange’ results. I used to use Libre 2 but on occasions I had sensors alarming all night, saying I was dropping seriously low. Fingerpricks showed this was rubbish and that I was in the high 6s.