Timezone Change and Daylight Saving

When the time zone of your phone changes, AAPS calculates IOB, basal and sensitivity for the past again from scratch, about 10 seconds after the change. While this runs, the graphs and values on the main screen may take a moment to update.

Timezone change for Omnipod Dash

Refresh the pump status in Manage → Pump
Temporarily select a different Profile and then switch back to your original or desired Profile

Timezone change for DanaR, Korean DanaR

There is no issue with changing timezone in phone because pump doesn’t use history

Timezone change for DanaRv2, DanaRS, Dana-i

These pumps require special care because AAPS uses history from the pump but the records in pump do not have timezone stamp. This means that if you change time zone in your phone, records will be read with different time zone and will be doubled.

To avoid this there are two possibilities:

Option 1: Keep home time and timeshift profile

Turn off ‘Automatic date and time’ in your phone’s settings (manual time zone change).
Your phone must keep your standard time as at home for the whole travel period.
Time-shift your Profile according to time difference between home time and destination time.
- Tap the Profile name on the main screen to open the Profile screen
- Select your Profile and tap ▶ Activate
- Set ‘Time shift’ according to your destination and tap Activate.
- e.g. Vienna -> New York: Profile Switch +6 hours
- e.g. Vienna -> Sydney: Profile Switch -8 hours

Option 2: Delete pump history

Turn off ‘Automatic date and time’ in your phone settings (manual time zone change)

When you get off the plane:

turn off pump
change timezone on phone
turn off phone, turn on pump
clear history in pump
change time in pump
turn on phone
let phone connect to the pump and fine-tune time

Timezone Change for Insight

The driver automatically adjusts the time of the pump to the time of the phone.

The Insight also records the history entries in which moment time was changed and from which (old) time to which (new) time. So the correct time can be determined in AAPS despite the time change.

It may cause inaccuracies in the TDDs. But it shouldn’t be a problem.

So the Insight user doesn’t have to worry about timezone changes and time changes. There is one exception to this rule: The Insight pump has a small internal battery to power time etc. while you are changing the “real” battery. If changing battery takes too long this internal battery runs out of energy, the clock is reset and you are asked to enter time and date after inserting a new battery. In this case all entries prior to the battery change are skipped in calculation in AAPS as the correct time cannot be identified properly.

Timezone Change for Accu-Chek Combo

The Combo driver automatically adjusts the time of the pump to the time of the phone. The Combo cannot store timezones, only local time, which is precisely what the driver programs into the pump. In addition, it stores the timezone in the local AAPS preferences to be able to convert the pump’s localtime to a full timestamp that has a timezone offset. The user does not have to do anything; if the time on the Combo deviates too much from the phone’s current time, the pump’s time is automatically adjusted.

Note that this takes some time, however, since it can only be done in the remote-terminal mode, which is generally slow. This is a Combo limitation that cannot be overcome.

Timezone Change for Medtrum

The driver automatically adjusts the time of the pump to the time of the phone.

Time zone changes keep the history intact, only TDD may be affected. Manually changing the time on the phone can cause problems with the history and IOB. If you change time manually double check the IOB.

When the time zone or time changes running TBRs are stopped.

DAYLIGHT SAVING (DST)

Time adjustment for daylight savings time.

Depending on your pump and CGM setup, jumps in time can lead to problems with AAPS to function correctly. For some pumps it is better to make time zone adjustments while awake before DST takes place and not during the night.

DST automatic adjustment for most pumps

However, the Loop will be deactivated for 3 hours AFTER the DST switch (usually 1am onwards) has taken place and AAPS will default to background basal as selected in your Profile. This is done for safety reasons - IOB may be too high due to duplicated bolus prior to DST change.
After DST has taken place, make a Profile Switch to the desired Profile to enable the Loop: tap the profile name on the main screen, then the round ▶ button (see Activating a profile).
You will also receive a notification on AAPS main screen prior to DST change that the Loop has been disabled temporarily. This message will appear without beep, vibration or similar sound.

If you bolus with AAPS’ calculator please do not use COB and IOB data unless you are sure this data is absolutely correct. Take caution and do not use this feature for a couple of hours after DST switch has taken place.

DST for Accu-Chek Insight

Change to DST is done automatically. No action required.

DST for Accu-Chek Combo

Change to DST is done automatically. No action required.

DST for Medtrum

Change to DST is done automatically. No action required.

DST for Omnipod Dash

Either allow AAPS to temporarily default to background basal after DST has taken place as explained above.
Otherwise, if you do not want AAPS to temporarily default to background basal overnight, you can change the time zone the day before DST is due to take place to avoid overnight disruption. NOTE THIS OPTION MAY CAUSE YOUR POD TO PREMATURELY EXPIRE. PLEASE HAVE SUPPLIES WITH YOU IF OPTING FOR THE FEATURE BELOW.

Actions to take before the clock change

Switch OFF any Phone’s settings that automatically sets the Phone’s time zone, so the user can change to a desired time zone that does not use DST. How to enable this will depend on your smartphone and Android version.
- Some phones have two settings, one for automatic setting of the time (which ideally should remain on) and one for automatic setting of the time zone (which you must turn OFF: Set automatically under Time zone in the screenshot below).
- Unfortunately, some Android versions have a single switch to enable automatic setting of both the time and the timezone. You’ll have to turn this off for now.

Find a timezone that has the same time as your current location but doesn’t use DST.
- A list of these countries is available https://greenwichmeantime.com/countries
- For Central European Time (CET) this could be “Brazzaville” (Congo). Change your phone’s timezone to Congo.

In AAPS refresh your pump and switch to your desired Profile.
Check AAPS’s IOB and COB and if this is inaccurate disable the Loop for at least one DIA or the maximum carb absorption time (Absorption max time), whichever is longer.
Actions to take after the clock change. A good time to make revert to local time zone is with low IOB. E.g. an hour before a meal such as breakfast. Ideally your COB and IOB should both be close to zero.