Libre numbers

I can not make sense of my Freestyle Libre numbers. I am very motivated by my meter numbers. But not Libre. I was alerted during the night I was going low. It said 58,did a finger check it was 120. I love the fact I can swipe it. But in my head ,these numbers are crazy. I do know it is reading tissue fluid. This transition is hard and confusing. Nancy50

I started on the freestyle Libra about 5 years ago. It was recommended by my endocrinologist. Used it for 3 to 4 months but couldn’t understand why it was so inaccurate. For me it was always 30 to 40 points off some people could live with that but I couldn’t. Change to the Dexcom and have had it ever since. I know it’s more expensive but for me it was worth every penny.


Do a lot of readings and see if the Libre is always off the same ammount. If it always reads 30 points low, no problem. Just subtract 30 points. If sometimes lower and sometimes higher, that’s more problematic.

Mine was always inaccurate for a day or so after I started it.

I just follow the curve so to speak. I am adjusting to the readings. I love that I can check my readings whenever. Nancy50

Each individual sensor I find is off by about the same amount, with sometimes it getting a little more accurate as time goes on. If it was more than 20% I used to call them in since I used it to dose sometimes. I think they want it to be 25% though. Like Gretchen mentioned I would always deduct points from the number it showed to get a closer number.

Do you need the low alerts? I have a Dexcom that gives me alerts, but I take vacay’s 1-3 days from wearing one and if I have a Libre on I will use it and scan sometimes. But I turn the alerts off.

One of the things, besides calling in ones that are too far off, remember an important part is the trends it shows. By the graph you can see if you are headed downwards or upwards, so even if it’s inaccurate it can be invaluable in telling you what your numbers are doing. But when I was just using a Libre I would complain about the inaccuracy all the time, even though I was happy to have it and I wouldn’t have wanted to give it up to go back to only finger sticks.

I use it for snorkeling and I check how close in numbers it is before I get in, then I watch the trend to know what my numbers are doing. In that case I am really just watching if I drop and how fast or much I am dropping.

Thanks,I do get low alerts,but I was taught to test before eating. I am having more confidence. Nancy50

My PCP’s husband uses one and she says it is VERY inaccurate, and it can swing wildly based on his hydration levels.

I have done many pair testing numbers, I can be very close on low. Highs are 15-20 points higher. I am 96% in range. Doing well.

Nancy Matulis

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I got my first Libre on ebay before they were available in the U.S. I always viewed it as more of a “trending tool” and more for getting AGPs for T2s. My original goal with the Libre was to see if afrezza was really as good as they were saying at stopping the post meal BG spike and I didn’t want to end up being a pin cushion.

The Libre is factory-calibrated to estimate blood glucose based on interstitial glucose which is the fluid between skin cells so its an estimate and everyone is different. You can calibrate it but you will need an app like Tomato and you will need to recalibrate it daily if you want it to be as good as a Dexcom.

The Libre 3 should be shipping soon but I expect it to be the same as the Libre 2 in accuracy.

Here is a good little overview from Levels which is one of the tech diet companies using them for diet control FAQ: Sensor Accuracy - FreeStyle Libre CGM vs Finger Prick Glucometer - Levels Support.

You could overcome this difficulty by taking a lot more readings - try 1 or 2 an hour. That will simulate the behavior of a Dexcom. The danger there is that you need to verify the accuracy of readings periodically because people regularly complain about accuracy issues and you don’t want to start dosing on inaccurate measurements. When you look at the data a lot, that’s a risk.

Because blood glucose numbers change a lot, the way your body is behaving wont be clear unless you have a LOT of readings. Dexcom reads a data point every 5 min. The goal will be to see how the data trends. Like, is it increasing or decreasing or staying steady over a 6 hour period.