Freestyle Libre


Technically the numbers should not be the same because you are measuring two different things. The Libre measures interstitial fluid glucose, whereas the glucometer measure blood glucose. The glucometer measure what your glucose is now and the Libre measures what your glucose was 15 or so minutes ago. (The time difference varies depending on each person and where you put the sensor. Abbot approves of the sensor being placed only on the back of the arm. Anywhere else might possibly give a different read - I don’t really know for sure how it would effect readings, I’ve never placed a sensor anywhere else but my arm.


Thank you so very much for the explanation!


I apologize in advance if I am repeating myself however I posted before that when you calibrate your Libre sensor you should be calibrating it during a somewhat fasting. Many hours either after or before you have eaten or hours after any physical activity or insulin shots (six hours)because that is when the interstitial readings and the blood readings will be the most similar. The glucometer manuals state the readings are ±70mg/dl during insulin injections or meals, which is one of Dexcom’s selling points. The best thing about the cgms are the data but more importantly the arrows. I had a Dexcom for a while and relied on the arrows, however, when my insurance stopped covering it, I started testing on my arm, then finger to know where my blood was heading if I couldn’t figure it out by my recent exercise, Meals., or insulin intake. If the readings are still different during a fasting period, you may want to switch to a libre sensor and xdrip+(android) or spike(apple), as you can fast and calibrate. My endocrinologist told me this, As well as the Dexcom rep, however I personally use the libre, blucon, and xdrip + with a ticwatch e because it was was relatively cheaper for those items and my Insurance is covering the libre at 3 sensors for $75


Wow! Thank you for sharing your expertrise! I did NOT receive anything with which to calibrate my sensor! I’ll contact my supplier right now. Everything you say makes perfect sense! Bless you!


You have to have another product and use apps to simulate calibrations.

MIAOMIAO or blucon nightrider

Contacting your supplier is futile


Ohhh, now I get it!. By calibrate you were referring to doing a fingerstick and sensor scan upon fasting. (Duh!) Thank you!


sorry, I should have suggested using xdrip+ or spike or at least specify that it is another app, however, I disagree with tony, you are not simulating, you are calibrating on xdrip+ , its just a different app and different algorithm from the libre unit. You still need the libre reader to start a new sensor, but after I have started the sensor, I leave it at home and just use my phone and watch with xdrip+ installed…I have a glucometer in my car, but I dont keep one in my pockets anymore… still have to keep insulin though. I mention xdrip because it Allows integration with 3rd party devices such as the blucon or miao miao which allows predicted lows, alarms, etc. More like a true cgm…


You cannot do a calibration on the reader - therefore you are simulating what the calibration would do if you could do it, but you can’t.

Just think like a left hander - life will be easier

but then, only the gifted have it

Just a little kidding!


My diabetes educator told me that everyone is different. Some people find the dexcom 100% accurate, other people cannot use the dexcom because the numbers are way off, same with the freestyle libre. All meters are off by a maximum of 10% (from what I read), so 10 points isn’t too bad (if it’s mg/l and not mmol/l). My sensors seem to work amazing, they do lag a bit though (after lows especially), so doing a finger prick here and there may be necessary until you get the hang of it :slight_smile:



Exactly. For me, the Libre is very accurate. <10 mg/dL difference to blood glucose meters in 95% of the time, <20 mg/dL every single time after the first 24 hours. Not every sensor works for everyone. Not even the much lauded Dexcom G6 is exempt from this.

I do however do one finger prick test daily, in the morning, to verify that the sensor is still okay.


Thanks! Ha, ha … I get it; my husband is a left handed!


Thank you!


There is a kind of a book

The natural superiority of the left hander

It’s a riot

You and my wife have a lot in common

I am trying to teach her to think lefty to no avail - most times she just looks at me like ET landed in front of her when I tell her how I perceive something

It is what side of your brain controls thinking

the right for lefties and the left for righties

they look at things completely different


When you use xdrip+, it works independently from the libre reader. The algorithms are different, but again, you can calibrate the xdrip, you can’t calibrate the libre. I personally thought the libre was more accurate at first. But after 6 months of using xdrip with the customization of the alarms, I only use the freestyle reader to start the sensor.


Great it works for you - glimp has calibrations but still not useful for my wife

There should be no need for all of this

The FDA would prob not approve libre ( I could be wrong ) if it had calibrations even if it would make life better

I believe the FDA has a goal of making like more miserable for diabetics - not kidding - the 12 hours libre warm up is proof


Crap. Why didn’t I think of that. My Walgreens store loves me. I’m sure they would take them back. Excellent idea. The jury is still out on me if I’m a type 1 or 2 or some kinda interesting cross between. So, I use it to see what type of foods I can get by with and to confuse the endo… And I agree, if your hard earned money goes into it…it should work like advertised.


I’ve been using the European Libre for 2 years and they would always read low and report false lows. However the 3 month A1c it predicted was usually .2 points lower than the lab results.

Just switched over to the US 14 day Libre system (with 1 hour startup) and its been reading about 8 to 19 points higher than actual, which really isn’t that bad. You have to remember that even figerstick readings can vary considerably.

Only switched to the US version as the European sensors off ebay were running between $93 to $112 per sensor. Can get the US sensor now for $43 for two sensors.

See how your system shakes out, but the new 14 day system is more accurate than the 10 day sensors I used a year ago. Just get the doctor to prescribe the 14 day system, as both 10 day and 14 day are being marketed right now.


I doubt there is any difference between the 10 and 14 day


Has anyone ever mentioned LADA to you? ( Latent Autoimmune Diabetes in Adults ) At the beginning the doctors have a tendency to misdiagnose you as a type 2 because you still make insulin for years, but slowly you make less and less insulin. Medications will sometimes work at the beginning because of that. But slowly you need insulin and eventually you have to have insulin for everything because you are really a type 1. It just takes a longer time to develop. They can test you for the antibodies.

My first endo got it wrong with me, never tested me, just assumed I was type 2. Even when I asked about it and told him I had an uncle that died from type 1.