First I would like to thank Deebee.it, specially Fabrizio Casellato and Irida Cami, the opportunity to test Abbott Freestyle Libre 2. Without them, this comparative test would not be possible.
Who am I?
My name is Sérgio Silva, I’m from Terceira island (Azores – Portugal), I’m 36 years old, I’m an IT technician and paraglider. My Diabetes appeared since I was 16 years old (1998). By August the 7th, 2018, I create the Portuguese Facebook group, entitled DiabéT1cos (www.diabet1cos.pt). I’m a user of an artificial pancreas (AndroidAPS + Accu-Check Combo) since August 2018 and I’ve recently collaborated in the translation into Portuguese of xDrip+ and AndroidAPS.
English translation by Sara Santos
What is the comparative test?
The objective is to compare Libre 1 with Libre 2, using official readers with the Libre 1 data, with Miao Miao and xDrip+ (with calibration plugin Dactrisae, recommended by the app development team for transmitters such as Miao Miao and Blucon). The Contour Next One meter is used to measure blood glucose with a capillary test.
It is important to note that since using the FreeStyle Libre (January 2018), it has been almost a general rule for the sensor to show lower values than the capillary test. So, most of the time, when it indicates that I’m in “Lo” when I can even be with 80 or even 90mg/dL. Let’s see how it goes now with Libre 2…
How will it be performed?
To ensure a more reliable comparison:
- The two Libres on the same arm, relatively close to each other since the readers only read the sensor corresponding to the version of the reader;
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Accessories and bands for MiaoMiao
- Sensors with same expiration date: 2019-07-31
- Libre 1: LOT 180909Q
- Libre 2: LOT 3515698
- Sensors placed and activated at the same time (unlike what I usually do). I did not put them in 24 hours before activating them, as this way it is possible to check the reaction of Libre 2 on the first day of use following what is officially recommended..
- Software: xDrip+ build 22 febbraio 2019 withTicwatch E as”collector”.
- Contour Next strips:
- LOT DP7KPEC01A – Expiration date: 2019-10
- LOT DP7FPEF03A – Expiration date: 2019-06
- Readers:
- Libre 1: 2.2.13/0.94
- Libre 2: 1.0.0.12/1.03
Performed tests
- Comparison of capillary test values with Libre 1, Libre 2 and xDrip+
- Check the Libres readings when the blood glucose value is updated on xDrip+.
- In situations where:
- Stable Blood Glucose
- Fast ascent/descent
- Slow ascent/descent
- Final comparison of sensor usage; average of 7 and 14 days.
Let’s start!
Sensors activated on February 22nd, 2019 at 11pm.
NB: Values in parentheses represent the difference between the blood glucose value and the capillary test result.
All values are in mg/dL.
1st DAY – February 23rd
First Reading 23/February at 00h
- Capillary: 102
- Libre 1: Error “Try to read again in 10 minutes”
- Libre 2: 89 (-13)
Libre 1 presented the error “Try in 10 minutes”, I was testing for 30 minutes and the error continued. I thought it would be better to remove it and place a new sensor.
That way, there wasn’t much time wasted comparing it to Libre 2. When I removed the sensor I noticed that the tip of the flexible strip of the sensor was crooked (I did not have one with the same expiration date as the Libre 2). I activated the sensor around 00:30, taking the first reading and calibration around 2:00 in the morning… I fell asleep and could not do the test one hour after activation.
Libre 1 sensor data: LOT 329696964
Expiration Date: 2019-05-31
Libre 1 reading at 2:05 in the morning
- Capillary: 74
- Libre 1: 53 (-21)
Reading at 7:30.
- Capillary: 95
- Libre 1: 71 (-24)
- Libre 2: 114 (+19)
- xDrip+: 139 (+44)
Reding at 21:15
- Capillary: 101
- Libre 1: 98 (-3)
- Libre 2: 101 (0)
- xDrip+: 101 (0)
For me, the usually most critical day after activation of Libre, also on xDrip, given the calibrations.
2nd DAY – 24/February
Reading at 7:05
- Capillary: 65
- Libre 1: 47 (-18)
- Libre 2: 53 (-12)
- xDrip+: 83 (+18)
Reading at 11:00
- Capillary: 91
- Libre 1: 70 (-21)
- Libre 2: 71 (-20)
- xDrip+: 111 (+20)
Reading at 14:45
- Capillary: 128
- Libre 1: 124 (-4)
- Libre 2: 143 (+15)
- xDrip+: 150 (+22)
Reading at 20:50
- Capillary: 131
- Libre 1: 111 (-20)
- Libre 2: 100 (-30)
- xDrip+: 116 (-15)
3rd DAY – 25/February
Reading at 7:05
- Capillary: 76
- Libre 1: 61 (-15)
- Libre 2: 63 (-13)
- xDrip+: 79 (+3)
Reading at 11:55
- Capillary: 94
- Libre 1: 80 (-14)
- Libre 2: 76 (-18)
- xDrip+: 97 (+3)
Reading at 16:15
- Capillary: 66
- Libre 1: 57 (-9)
- Libre 2: 62 (-4)
- xDrip+: 74 (+8)
Reading at 22:25
- Capillary: 146
- Libre 1: 132 (-14)
- Libre 2: 131 (-15)
- xDrip+: 133 (-13)
4th DAY – 26/February
Reading at 6:50
- Capillary: 93
- Libre 1: 84 (-9)
- Libre 2: 85 (-8)
- xDrip+: 86 (-7)
Reading at 11:55
- Capillary: 87
- Libre 1: 73 (-14)
- Libre 2: 73 (-14)
- xDrip+: 90 (+3)
Reading at 22:15
- Capillary: 123
- Libre 1: 110 (-13)
- Libre 2: 121 (-2)
- xDrip+: 122 (-1)
5th DAY – 27/February
Reading at 6:55
- Capillary: 99
- Libre 1: 79 (-20)
- Libre 2: 81 (-18)
- xDrip+: 98 (-1)
Reading at 12:10
- Capillary: 105
- Libre 1: 88 (-17)
- Libre 2: 104 (-1)
- xDrip+: 100 (-5)
Reading at 22:15
- Capillary: 113
- Libre 1: 121 (+8)
- Libero 2: 127 (+14)
- xDrip+: 113 (0)
6th DAY – 28/February
Reading at 6:45
- Capillary: 91
- Libre 1:75 (-16)
- Libre 2: 82 (-9)
- xDrip+: 93 (+2)
Reading at 12:45
- Capillary: 88
- Libre 1: 79 (-9)
- Libre 2: 85 (-3)
- xDrip+: 95 (+7)
7th DAY – 1/March
Reading at 7:10
- Capillary: 113
- Libre 1: 72(-41)
- Libero 2: 130 (+17)
- xDrip+: 82 (-31)
Reading at 9:20
- Capillary: 78
- Libre 1: 46 (-32)
- Libre 2: 66 (-12)
- xDrip+: 74 (-4)
Reading at 11:35
- Capillary: 69
- Libre 1: 43 (-26)
- Libre 2: 64 (-5)
- xDrip+: 80 (+11)
Reading at 16:10
- Capillary: 97
- Libre 1: 46 (-51)
- Libre 2: 88 (-9)
- xDrip+: 91 (-6)
Reading at 21:45
- Capillary: 71
- Libre 1: LO 40? (-31)
- Libero 2: 65 (-6)
- xDrip+: 77 (+6)
Values after 2 xDrip+ rapid ascent readings
- Capillary: 124
- Libre 1: 92 (-32)
- Libero 2: 87 (-37)
- xDrip+: 100 (-24)
Values after 2 rapid descent readings on xDrip+
- Capillary: 85
- Libre 1: 101 (+16)
- Libre 2: 126 (+41)
- xDrip+: 109 (+24)
And at the end of the 7th day, Libre 1 ends up dying, the readings were already strange on the 1st of March, and then it ends up giving a reading error, so that the reading is repeated in 10 minutes and after a while there is an error so that the sensor can be changed. There was supposed to be a second part of the test, with comparison of the 14 days, but in this case I end up staying only for the first 7 days.
Statistics for the first 7 days
Averages of the difference between the finger test and the values presented in the 26 tests performed (not counting the first test, since Libre 1 did not present values in the first result):
- Libre 1: -17.12
- Libre 2: -6.12
- xDrip+: -0,73
Average of 7 days
Libre 1: 87
Libre 2: 98
xDrip+: 105
A1c
(converting the average of the Libre readers as an estimate)
Libre 1: 4,83%
Libre 2: 5,44%
xDrip+: 5,3%
xDrip+ calibration chart for the 7 days of use
TIR (Time in Range)
Range of the target: 70-170
- Libre 1: Above: 2%. In range: 67%. Below: 31%
- Libre 2: Above: 1%. In range: 75%. Below: 22%
- xDrip+: Above: 2%. In range: 91%. Below: 5%
Patterns of 7 days 
My conclusions
In my opinion, Libre 2 behaved much better than Libre 1 and I noticed this in the first 24 hours. As I said before, they end up being the most critical hours in relation to the values presented. After the initial 24 hours, and as usual, Libre 1 always showed much lower values than the test result on the finger and xDrip+. In turn, Libre 2 indicated higher values than Libre 1 and closer to the capillary test. Observing my results, Libre 1 would spend most of the time in hypo, which does not correspond to the truth. Therefore, if I trusted only Libre 1 (without capillary tests) I would always be correcting a non-existent hypo, which in turn would increase the laboratory test of my A1c. I still trust the values of xDrip+ and if I didn’t, I wouldn’t be able to use artificial pancreas. After all, all decisions regarding the amount of insulin are analyzed at each result received, every 5 minutes.
In this test, we can also see that many of the irregular values of xDrip+ have an influence on the malfunction of Libre 1, which ended up dying after 7 days.
In order of preference:
- Libre 1 + Miao Miao + xDrip+ solution
- Libre 2
- Libre 1
Is Libre 2 an alternative to Miao Miao with xDrip+?
My answer is no! It is not an alternative, neither far nor close, who was waiting for the Libre 2 not to have to buy the Miao Miao, in my opinion was a waste of time.
Libre 2 is a FGM (Flash Glucose Meter), instead of Miao Miao that converts a Libre into CGM (Continuous Glucose Meter), which makes it necessary to pass the reader through the sensor to have the value in an episode of hypo or hyper.
It seems that the only data that is transmitted by Bluetooth is the information to trigger the alarm. A curious thing happened to me only once and I don’t even know how I did it, I could see in my mobile phone, in the Bluetooth menu a device called “ABBOTT56456” (the numbers weren’t these, because I couldn’t memorize them), but right after that it disappeared. Is there anything planned to connect to the mobile phone, when near the reader, as a warning for hypo or hyper?
The alarms on the xDrip are silenced for a certain time, by default 30 minutes in the hypo and 2 hours in the hyper, the time that supposedly takes us to get out of a hypo and the insulin acts in case of hyper and, in case we continue in hypo or hyper, the alarm rings again. In the case of Libre 2, it is played only once in each episode, that is, if you have hypo and silence the alarm, it will only ring again when you leave the hypo and enter it again, which in a night hypo and in the middle of tiredness and sleep, may not have great effectiveness in preventing serious episodes. On the other hand, I understand how it is not possible to calibrate Libre 2 and how it happens to me to have values always lower than the capillary test, Libre 2 would be beeping for most of the day. Another available alarm refers to the distance of the reader in relation to the sensor for more than 6 meters, which really must have the idea of alerting that we may not be being monitored, in cases of hypo and hyper, but I keep thinking, if I get so far away, how will I hear the alarm? If I leave home and leave the reader behind by forgetting, how will I hear the alarm?
And how will remote monitoring of glycemia be done? As far as I can see, to date, it will be just like in Libre 1, using LibreLink on an NFC-enabled mobile phone to pass the phone through the sensor to read the value and then transmit it to the follower, who uses LibreLinkUp, but without receiving the graph of the day and only the value seen at the moment.
It’s curious that Libre 1 was released more than 2 years ago in Portugal and the two apps are not available for download at Play Store (Google) or App Store (Apple) in Portugal.
What about the calibration?
It’s unavailable in Libre 1 and 2… as seen in this test and by the average of the tests performed at some time of the day, the xDrip+ with calibration is much closer to the value of the capillary test and the Libres are not.
We remember that these are not absolute conclusions, but relative to the experience of the writer. To draw safe conclusions, Diabetes Technology Society tools to calculate risk around MARD need more data points (this article reports 26).
The values presented by xDrip are more often higher than capillary glucose: this, especially when used with an AAPS system, could create a risk of overdosing insulin.
Thanks to Tim Street for the precious feedback.
©Riproduzione riservata
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Enjoy!
Da Padre a padre, dico grazie all'autore per aver fatto sorridere la mia bambina. Ci ha relagato uno sprazzo di magia
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If the communication between xDrip + and Miao Miao remains as good and stable as the original Chinese app, it will be a really wonderful thing! And I would be even happier if Miao Miao were integrated into 
