Freestyle libre - time lapse?

Firstly, you need to attach the sensor then leave it unactivated for 24 to 36 hours to allow time for your body to get used to a foreign body. Doing this should stop the silly readings the first day.

Secondly, the interstitial fluid is BEHIND capillary blood, so if you are just doing a test to compare the accuracy, you test first, wait 10 to 15 minutes, then scan.

If you do some accuracy comparison tests you should be able to work out if your sensor reads higher or lower than your meter and make mental adjustments. Each sensor I've used has been different. Some have read higher, some lower, and my current one is spot on. I just do a few averages of the differences, and if that is, for example, 1mmol/l higher then I make a mental adjustment of 1mmol/l.

Good luck! I see many T1s on here that swear by the Libre for having sorted out their injecting regimes. I just use it to improve my T2 diet-only control.

Hi Esther444

Firstly, welcome to the forum

One thing to be aware of is that if your glucose level is changing fast, ie goingup or down, it can take up to approx 15 mins before the Libre sensor will reflect the level suggested by the finger prick test. If your glucose is pretty level, then you may well get results almost exactly the same.

Another thing to be aware of is that every different glucometer you might use, even if the same drop of blood etc, can and often does, give a differing result so it's not always helpful to think both sensor and glucometer readings should be same/close.

The Libre is excellent at showing direction of whether your glucose level is going up or down, whether changing fast or not quite so fast, just by looking at the arrow next to the reading. Having said that, I've had the arrow pointing 45 degrees up but, 2 mins later, my reading is a bit lower so just learn to interpret well.

It's generally advised not to adjust insulin on the basis of the Libre. If the Libre reading suggests the need for a bolus, or going hypo, check with your glucometer before deciding on the treatment necessary, just in case the Libre isn't quite accurate enough at that time.

I'm sure you'll find the Libre a very useful tool.

Esther444 said:

Hi All,

Not sure if I'm being a bit dim here but have read through many many threads on the Libre and people have mentioned the differences between interstitial fluid and blood.... so my question is - to compare would you test on the libre and then 10 mins later on another meter or the other way round?

I started with a sensor just after new year, put it in and started it after I hour as instructed ( hadn't done a lot of research at that point

). I just noticed that it was consistently out (as compared to my pump meter) by what I consider quite a lot sometimes up to 2/3 mmoLl/L either way, so not great if its reading 5 and I could be 2 !!

So basically it scared me a bit ( don't deal well with hypos

) and I haven't used the other sensor yet, i bought a starter pack of two and don't want to waste it.

Grateful for any thoughts.

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Hi @Esther444,

I would agree with @Energize that I wouldn't use the Libre to inject insulin. I use it more to tell me what my blood glucose is actually doing (up/down/ going straight) and also more general patterns - do I need to take my insulin slightly earlier before this meal, how is my basal acting, am I likely to have a hypo in a bit or am I staying fairly steady, is it going to keep going up or will it start coming down soon - than I do for actual 'readings'. I definitely don't rely on it exclusively. It gives me a lot more confidence when I am out and about, and also more of an idea of how different things affect me, like I can see it creeping up when I'm stressed.

I love it, personally, it's very useful. I find it tends to get a bit 'overexcited' - once I get to around 4.5 it tends to underread and tell me that I'm hypo, and will overread from about 14 upwards. I don't rely on it exclusively, but it has definitely helped my control - it showed me that I don't tolerate weetabix for breakfast particularly well, for instance - and it is also helping me make better decisions about my care. Hope this helps!

Bluetit1802 said:

Good luck! I see many T1s on here that swear by the Libre for having sorted out their injecting regimes. I just use it to improve my T2 diet-only control.

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@Bluetit1802 - can you tell me more about how you use it to improve your diet control? I'm T2 on metformin, went low carb 7 months ago and have since reduced HbA1C from 62 to 40.... but every single higher-than-I-want reading irks me.

Am considering shelling out for some Libre sensors. Having discovered I can use my Android phone instead of buying a reader makes it seem sooooo much more realistic . But seeing the delivery charge makes it look soooo much more expensive!

BarbaraG said:

@Bluetit1802 - can you tell me more about how you use it to improve your diet control? I'm T2 on metformin, went low carb 7 months ago and have since reduced HbA1C from 62 to 40.... but every single higher-than-I-want reading irks me.

Am considering shelling out for some Libre sensors. Having discovered I can use my Android phone instead of buying a reader makes it seem sooooo much more realistic . But seeing the delivery charge makes it look soooo much more expensive!

Click to expand...

There are lots of diet only T2's on the forum using the Libre, at least part time. It reads your glucose levels every 15 minutes, 24 hours a day for 2 weeks. Then expires. You also get a reader with which you can scan the sensor for an instant reading. The software produces beautiful graphs of all the readings, showing you everything there is to show. All the rises and falls. You can download the 15 minute readings to a computer, and these show the times and the levels every 15 minutes for the whole period. You can tell the reader when you are about to eat, go to bed, get up, snacks, anything you like, so you can see from the graphs and 15 minute readings what each event has done to you. I find it invaluable. I wish I could afford to use it full time. They are especially valuable for wearing on holidays when routine and foods change, and you can dispense with finger pricking at inconvenient times.

Barbara, if you're planning on using your Android phone to scan, make sure it's got NFC. Not all android phones do. I'm type 1 and am not at all self-conscious about injecting/testing in public, have been shooting up while waiter has been enquiring how I've been enjoying my meal, but I've found that while the libre reader can usually find the sensor easily and discretely, I can spend ages waving my phone with Librelink on it round my arm and get nothing and people start thinking why's that tube waving his phone around his arm? It is just so not discrete.The reader is a one off cost of 57 quid, palm sized, no-one notices, if they notice at all, they probably think I'm scratching my arm .

My phone does have NFC... I have posted a question elsewhere to check if anyone has used this specific model - Samsung S4 mini.

I guess the cost issue is about how often you are going to use it. If you are going to use it all the time, it costs a packet. I'd like to think that - since I'm wanting to use to refine what is already pretty good control - I may just use it for a short time, and then from time to time, rather than continuously. In that context, the 57 for the reader feels like a lot. Heck, I test ketones (£30 for the meter, then 80p per strip) and I know in my heart of hearts I don't really need to. But I like gadgets. And information.