Recommended sensor start protocol with Tandem and iPhone

In the past, I had no problems at all starting a new sensor via the iPhone app, and then following the Tandem’s instructions to “skip” a code entry to join an already started session.

After the Control IQ update, this hasn’t worked reliably - either a problem with the sensor believing it has been started twice (and refusing to start) or the session is started in manual mode requiring every 12 hour bg calibrations.

I’ve had two subtlety different answers on the right order to do things. Last time, I was told to stop the phone session, stop the pump session, start the phone session, and then join the started session via skip on the pump. This evening I was told to stop the pump session, start the session on the pump (and enter the code), and let the phone sync without any intervention.

Anyway, seems like there should be a write-up on this somewhere, but I can’t find anything.

Did you also start using a new Dexcom transmitter? Dexcom has added new checks to prevent sensor restarts. 8G and later transmitters have more checks.

Hopefully another tandem user can help. I’m getting tslim soon and will be checking for answers.

I just got my Control IQ a few days ago. My Tslim is running and displaying G6 data but it says in Bluetooth Settings that my Mobile Connectin is ON but I am not paired with my mobile. This could also have an impact on your ability to connect.

Ignore the Bluetooth settling for now, it had nothing to do with the G6 transmitter.

I can’t be of much help, since I’m not an iPhone user and don’t use the Dexcom app. I usually do sensor starts on the pump, though, not the phone with the app I do use. It just works better for me. Shouldn’t the Dexcom app figure out that there’s new data and display it without you doing a thing to start a new session on your phone? The transmitter should tell the mobile that a new session was started.

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The session started last night via the second protocol (only use the pump to stop/start) eventually synced with the phone without intervention. That’s good. I’ll do that from now on.

Still… I’m frustrated that, for me at least, the method I used to start sessions for years failed 3 times, and there’s no documentation that describes best practices. One solid bit of advice I can offer: the “skip entering a code to join an existing session” feature of the pump shouldn’t be used.

I use android and Tandem, but the way to do it is:

  1. With the Dexcom App - “Stop Sensor” with phone.
  2. Once sensor is inserted, Start new sensor with Code with the Dexcom App on phone.

Don’t do anything with Tandem pump(stopping sensor, starting sensor). The linking to the new sensor on Tandem automatically happens. You don’t have to do the steps on both Dexcom and Tandem. Only do the steps in one spot (Dexcom).

I always start my new sensors from my pump. Then I just hit start on my phone.

Dexcom G6 is designed to monitor BGs in using MDI or insulin pump. I always use iPhone to start a new G6 sensor or transmitter. I don’t want to mess up the Dexcom G6 system by using insulin pump to start new sensors and transmitter.

After G6 is up successfully, I then input new transmitter ID in Tandem Pump setting and not entering sensor code in Tandem Pump for warm-up. The Tandem Pump system will catch up the G6 system data very quickly.

Following up, a few months later: only using the pump to start the session has worked flawlessly.