Libre 2 reading high

[Grandadfatboy]

Hope this post finds you all as well as you possibly can be.

I've gone back to finger pricking at important times of the day. What started it was a reading of 16.4 in the night. I came downstairs with the intension of having a light snack and introducing some insulin. However, I though I'd confirm this high reading with a finger prick. The finger prick recorded a 12.4, so I took no action.

I have been finger pricking before all meals for a while now, and randomly after meals too. I did wonder if it was my L2 sensor reading incorrectly, but the pattern continued with a new sensor. In all tests the finger prick has recorded lower than the sensor reading, with one or two readings being identical.

It now explains why my BG levels have dropped much lower than I expected after meals, as I was adjusting the level of insulin based on the L2 sensor reading and not having performed a FP. I must say that although I've only been FP for about 10-14 days my fingers are already complaining, with some finger tips refusing to bleed, but I guess you would all know about that.

Anyway, I'm slowly getting back into my “normal” range and was wondering if anyone else is having the same experience with the L2 reading higher than actual?

 

[becca59]

I’m sorry no. Mine tend to be pretty bang on accurate apart from the first and last day.

 

[Deleted member 527103]

CGMs like Libre are brilliant pieces of kit but only if you understand their limitations. Sadly, DSNs seem not to explain these so we have to learn ourselves.
The main limitations are
- Libre is designed to be most accurate at “normal” levels. This is between about 4 and 9. For this reason it is ALWAYS recommended to test highs and low with a finger prick before treating (unless you are experiencing an obvious hypo).
- When pressure is applied to a CGM, such as lying on it when you are asleep, it will report a false low. This is called a compressor low and is another reason for testing highs and lows before treating.
- Some of us find our bodies initially react the the alien object stuck in our arms. As a result, Libre readings may be inaccurate for the first day or two. Therefore, some of us insert our sensors up to 48 hours before activating.
- CGMs do not read blood, they read interstitial fluid. These readings are about 15 minutes behind finger prick readings. However, Libre accounts for this delay by extrapolating the current trend on the graph. This works well most of the time. However, if the trend changed direction in the last 15 minutes, Libre does not know and will extend the wrong trend resulting in reports of highs that take longer to come down and hypos that take longer to recover. Again, another reason for checking recovery with finger pricks.
- some Libre can be more inaccurate than others. If this happens, Abbott is pretty good at replacing them if you report it to them.
- Libre is factory calibrated. Some of us find our body is different to “factory man” and would like to calibrate the readings. There are a number of unofficial apps such as xDrip, Diabox, Shuggah, … that allow calibration. They also have the added advantage that they can take the readings from Bluetooth so you do not need to scan the sensor. However, these rarely have good setup instructions and assume a level of technical wizardry.

I think my first point may account for your higher readings.

I also noted that you said your fingers are sore from less than 2 weeks of finger pricking. This may mean you need to review your finger pricking technique. Before the popularity of Libre, many of us wer finger pricking 10 times a day and did not have sore fingers.
The usual advice is
- adjust the prick depth to the shallowest that will extract blood.
- make sure your hands are clean and warm. Washing in warm water helps both of these requirements.
- prick the side of the fleshy part of your finger.
- rotate your fingers. Make sure you use all fingers (some say not to use fire fingers but I have never had an issue).

 

[PatsyB]

I tend to use finger prick also if my libra starts to say it be high but most of the time it is pretty accurate am so pleased to be on it xxx