Freestyle libre 2 after 30 weeks

[kalabati]

Hi everyone,

I have gestational diabetes sine the beginning of pregnancy and I was using libre 2 all the time. I checked them with finger pricks sometimes and they were pretty accurate alle the time, but something happened after 30 weeks of pregnancy. All my sensors show higher fasting and postrpandial than accucheck and countour next. Difference is quite big like about 1.5-2 mmol/l. I reported faulty sensor but new ones have the same issues, so it's like the the 3rd one after 30 weeks (I am almost 34 weeks now) and they all do the same. My A1c didn't change they check it every 4 weeks and it was 5.0%, then 4.9%, then 5.0%, so I assume the problem with libre not the glucosometers? Just these 2 mmol/l difference if they are true would put me in insulin. I am worrying that I don't start treatment if I should but I am afraid to start if I shouldn't...
Why is this happening in late pregnancy?

Thank you for any responce

 

[HairySmurf]

Very probable that the Libre 2 is giving you inaccurate readings. You might have been unlucky and gotten bad replacement sensors or there might be some other factor involved. It is very highly unlikely that two finger prick meters would both become inaccurate at the same time and yet (roughly) agree with one another. I've experienced similar problems with the Libre 2.

If you'd like to be certain you can get control solution from a pharmacy for testing your finger prick meters. Not sure about the Accucheck, but the Contour Next requires special control solution made specifically for that meter. You shake the bottle well, put a drop of control solution on a clean non-absorbent surface (I used a piece of plastic), test that with the meter as if it were a drop of blood and the meter gives you a reading. Each pot of test strips has a control range printed on it. If the solution gives you a result in that range, the meter and the pot of test strips are good. I repeated the control test a few times and found that the meter would typically give a reading right in the middle of the control range - i.e. close to true objective accuracy, on average. A couple of studies from a few years ago comparing the accuracy of many finger prick meters found that the Contour Next was the most objectively accurate meter available at that time (2017, 2018). Short of going to a doctor and asking for a fasting blood glucose test to be checked in a lab, testing one or both of your finger prick meters would be good enough I think, especially if they both roughly agree with each other. My pharmacy actually ordered and gave me the Contour Next control solution for free. I'm not sure if that applies in the UK - in Ireland all diabetics get access to a long term illness scheme that pays the cost of certain medications and supplies in full. If it's not free in the UK it's not likely to be very expensive.

I've tried investigating the reasons a CGM can become inaccurate and found little information. Perhaps something about hydration - how much fluid is in the fatty tissue the sensor filament sits in? Perhaps changes in the volume of fatty tissue in that location? Nobody seems to know for sure, and Abbott aren't exactly forthcoming about the causes of issues with sensor accuracy.

 

[Melgar]

Hi there @kalabati . I agree with @HairySmurf . Just to add CGM’s analyze your interstitual fluid , that is the fluid between your cells. It relies on blood being secreted into this fluid. This slow blood secretion causes a lag in reading and analyzing your blood sugar. It’s always behind, as it were. Your glucometer reads and analyzes your blood directly, so your results are immediate. So when you have blood sugars that are either rising or falling quickly, the CGM may show a different result because of the time lag. So, blood sugars rising then falling following a meal would create changing blood sugars due to metabolization. Your two devices may show different results. Your glucometer is very likely the more accurate of the two. I have a Contour Next and I find mine reads a little low. Factor in a 15% +/- allowable error on both devices and that may produce a difference.

 

[kalabati]

Thank you @HairySmurf and @Melgar for your responses! I will probably stick to Contour Next for the rest of my pregnancy, just will make sure it's accurate. Libre gives me to much anxiety and the problem that I usually take into account the delay, but now it never goes to the point which finger pricks show.

 

[HairySmurf]

I have a Contour Next and I find mine reads a little low. Factor in a 15% +/- allowable error on both devices and that may produce a difference.

The Contour Next does indeed read a little low - this study lists the 'bias' of the meters tested - Link - Contour Next came out with an observed bias of -1.2% on average. If that meter gives a value of 5.9 mmol/L, averaged over many tests, the actual value is closer to 6 mmol/L. Some meters have a smaller bias, some much larger. In reality different meters are more or less accurate at different blood glucose concentrations - one might be more accurate than another at high BG levels, but the other way around at low levels, due to variations in the design and manufacture of the test strips. The Contour Next was found to be most consistent of all studied though - closer to the mark more often than any other meter tested in that study and in this other study - Link

For most purposes though meters with cheapest test strips are just fine. I just happen to be able to get a pot of Contour Next strips for free off the government here on the health scheme for diabetics, so might as well use the best meter I can find for which I can get the free strips.

 

[Tinkerbella5]

I was given the libre 2 on Tuesday but am still using my meter the agamatrix but the libre is causing me more anxiety because of the massive difference,my libre showed 6.3 and agamatrix 7.2, I got told I should use libre for accuracy but I don't think I trust the libre.

 

[LittleGreyCat]

I was given the libre 2 on Tuesday but am still using my meter the agamatrix but the libre is causing me more anxiety because of the massive difference,my libre showed 6.3 and agamatrix 7.2, I got told I should use libre for accuracy but I don't think I trust the libre.

I think the Libre 2 is very good for showing trends, but for accuracy you are better off with a finger prick.

With the Libre 2 (other CGMs are available) you get to see what your BG is doing between finger prick testing and also overnight when you are asleep.
So a Libre 2 for trends and a finger prick for immediate accuracy is a good combination.
Noting that accuracy in BG measurement is always there or thereabout.

 

[Dr Clive]

I've been using freestyle libre 2 since February. It has revolutionised my diabetic control, particularly now that I'm on a regime of injecting rapid acting before meals and long lasting insulin in the morning.
It shows trends well and reacts to exercise, food and jelly babies when necessary in order to drive.
Abbott have responded very quickly to any error messages and have replaced sensors within two days.
I thoroughly recommend their use.
Dr Clive Wheeler

 

[CottonCutiePies]

Hi, I had problems with libre 2. I could get an accurate reading that was even close to my finger prick result. I'm now using dexcom g6 and omnipod5. My results are almost identical, my time in range has increased also. After 34 years of battling my diabetes, which incidentally started as gestational, I'm finally in control, better late than never as they say. Some who've gone over to omnipod 5 are being given libre2+, which has many issues like not giving accurate reading and losing signal between sensor and pump. If you can see if you can be put on dexcom for the remainder of your pregnancy.