Time in range accuracy

I have been using TSlim x2 for about 2 months. I have the TConnect app on my phone. I was just wondering about the accuracy of the time in range number. About a week ago it said 100% and I know that after dinner the previous night my glucose was over 200 for about 2hrs. I called Tandem and was told to delete the TConnect app and re-install it. The numbers seemed good for the next several days, but now the same thing happened. It says 100% but last night I was out of range for about 2hrs?
Also, other than the 3 day reminder to change your infusion set is there somewhere on the pump where you can see the time and date of your last infusion set change?

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Hi @edmundo do you have Dexcom on your phone? I would compare tir from Dexcom with tir from Tandem for starters. One source for error could be losing connectivity between the CGM and the pump. Other sources could be the app as in a software issue. My tandem mobile app just has a reminder for set change. It is a countdown timer.

Double check the glucose targets used to calculate the TIR report.

Ed @edmundo, other than your BGL readings developed by your CGM, the approximate 24 hour TIR is governed by when values you have entered in the app for your limits. Right now, my t;Connect app reads 85%. I keep my Tandem range set as 75 - 160 mg/dl.

Also remember that if those 200+ reading were more than 1,440 minutes old, they would not be included in the % calculation.


This is just a guess but I wonder if the percentage is rounded? If you had one hreading for 2 hours over say a 30 day period, you would be in range over 99%of the time.

The values were entered during my training session 70-180. Is that typical or standard?

Yes Ed @edmundo, the 70 - 180 mg/dl is the universal standard, and what most people use. I was offering a possibility for " a why" your % wasn’t what you expected.

As a note, I do use the standard 70 - 180 range for one of my reports - the universal AGP. I have my Tandem set a little “tighter” so I receive earlier warnings, especially because when I’m out exercising I can preempt a low. Also, on my Dexcom, I use a split range: 11 hours overnight a range of 85 - 140 to help keep me safer. In older age, my reactions and awareness are slowing down.

By analyzing differences between TIR with the different parameters, I have been able to push up my HbA1c from what we thought was too low and maybe dangerous; I’m still under 6% but now in the upper 5s.

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I was just low ~49 and my TIR on dexcom for 3-day was 0% low, 0% very low and I had to toggle it to 7day, and back to 3 day, to get the updated data. Perhaps the Tandem TIR also has some lag in calculations or requires a “regeneration” (sorry that’s a reference from the early days of computer aided design). Did you notice any differences with the software lately?

@Joe, there is, at times, a delay in the web-based t:Connect app on the web; it was mentioned in some older documentation “periodic update”. When looking at “Reports” in Tandem Portal (Tandem Source), after loading and glancing at the report I hit the refresh button and watch the data line on the current day extend itself.

Nothing “slow” about this compared with the computers in the early 1960s when I took a degree in DIGITAL Computer Technology - “digital” emphasized because most computers at that time were analog.

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