# What happens to your CGM data for the extra hour on Daylight Savings Time Fallback day?
**URL:** https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579
**Category:** C/GM
**Created:** [November 7, 2017, 4:58am UTC](https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579 "2017-11-07T04:58:15Z")
**Posts on this page:** 20
**Page:** 1
### Author:  [@Michel](https://forum.fudiabetes.org/u/Michel)
#### Post date: [November 7, 2017, 4:58am UTC](https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579/1 "2017-11-07T04:58:15Z")
When I look at our 1:00-2:00am data for DST Fallback night, I cannot detect a difference: the curve, for us, is continuous at 1:00am and at 2:00am, and it is also differentiable.
So I am curious: what do you think happens to the data for the extra 1:00am hour on Fallback day? What is intriguing to me is that I was expecting to see somthing weird at 1:00am but did not.
Why my expectation:
- if they use the 1st 1:00am hour, we should see a discontinuity at 2:00am
- if they use the 2nd 1:00am hour, we should see a discontinuity at 1:00am
- if they use a combo of both we should see discontinuities at both 1:00am and 2:00am
I don 't detect anything in our data, but it was not a very eventful hour, so it may be that I would not be able to see a big discontinuity.
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### Author:  [@Sam](https://forum.fudiabetes.org/u/Sam)
#### Post date: [November 7, 2017, 5:58am UTC](https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579/2 "2017-11-07T05:58:44Z")
Umm, the data doesn’t change… just the number on the clock does.
Every time I’ve crossed the international dateline westbound and skipped a day I’ve wondered what would have happened if I’d committed a crime on that date that didn’t exist in my life. Could I be convicted by a jury of my peers— I certainly think the case could be made for reasonable doubt.
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### Author:  [@Michel](https://forum.fudiabetes.org/u/Michel)
#### Post date: [November 7, 2017, 8:09am UTC](https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579/3 "2017-11-07T08:09:20Z")
Well, that is not correct. There is _real_ data for two of the same hour.
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### Author:  [@Thomas](https://forum.fudiabetes.org/u/Thomas)
#### Post date: [November 7, 2017, 12:03pm UTC](https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579/4 "2017-11-07T12:03:24Z")
Yuck.
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### Author:  [@Thomas](https://forum.fudiabetes.org/u/Thomas)
#### Post date: [November 7, 2017, 12:13pm UTC](https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579/5 "2017-11-07T12:13:37Z")
I do think you have to be careful about what conclusions are drawn.
This is specifically the G5 Transmitter going to an Apple iPhone on iOS 11.0.1 running the Dexcom G5 Mobile App v1.7.3 going into the Dexcom Clarity Servers.
Clearly something is less then “perfect” but exactly where the disconnect lies may not be immediately obvious.
@Michel - I am glad our lack of overnight straight line was able to assist you in your musing.
ha ha ha
😉
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### Author:  [@CatLady](https://forum.fudiabetes.org/u/CatLady)
#### Post date: [November 7, 2017, 2:30pm UTC](https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579/6 "2017-11-07T14:30:09Z")
Cue the Twilight Zone theme song… 🎶
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### Author:  [@docslotnick](https://forum.fudiabetes.org/u/docslotnick)
#### Post date: [November 7, 2017, 4:47pm UTC](https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579/7 "2017-11-07T16:47:44Z")
XDrip+ just added an hour, i.e. there were two 2am-3am time frames on the continuous track.
So the track stayed constantly reading correctly, only the times were changed to protect the innocent 😂
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### Author:  [@Sam](https://forum.fudiabetes.org/u/Sam)
#### Post date: [November 7, 2017, 4:50pm UTC](https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579/8 "2017-11-07T16:50:13Z")
That’s an extraordinarily dumb design… why not just have the clock go from 0159 to 0100 and the data stream continue unbroken
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### Author:  [@Sam](https://forum.fudiabetes.org/u/Sam)
#### Post date: [November 7, 2017, 4:51pm UTC](https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579/9 "2017-11-07T16:51:28Z")
> [@docslotnick](#):
>
> So the track stayed constantly reading correctly, only the times were change
That’s how it should be and any design other than that is totally silly
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### Author:  [@docslotnick](https://forum.fudiabetes.org/u/docslotnick)
#### Post date: [November 7, 2017, 4:52pm UTC](https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579/10 "2017-11-07T16:52:22Z")
> [@Sam](#):
>
> why not just have the clock go from 0159 to 0100
That would take some fancy programming, and the FDA would take years to approve the change.
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### Author:  [@Boerenkool](https://forum.fudiabetes.org/u/Boerenkool)
#### Post date: [November 7, 2017, 5:40pm UTC](https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579/11 "2017-11-07T17:40:32Z")
Does THAT require FDA approval? 😲 Unbelievable.
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### Author:  [@docslotnick](https://forum.fudiabetes.org/u/docslotnick)
#### Post date: [November 7, 2017, 7:00pm UTC](https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579/12 "2017-11-07T19:00:31Z")
> [@Boerenkool](#):
>
> Does THAT require FDA approval? 😲 Unbelievable.
When I asked a while back if they could add a dimming feature to the G5 receiver because the backlight was way too bright they told me that it wouldn’t be until G6 was out because FDA approval takes so long.
So yes, every tiny little change they make has to be approved.
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### Author:  [@docslotnick](https://forum.fudiabetes.org/u/docslotnick)
#### Post date: [November 7, 2017, 7:18pm UTC](https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579/13 "2017-11-07T19:18:32Z")
> [@Thomas](#):
>
> I am glad our lack of overnight straight line was able to assist you in your musing.
>
> ha ha ha
The reason I didn’t post a screenshot is because I didn’t want to make public my excursion to 270 😭. The 22u correction I took brought it down in a few hours
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### Author:  [@Boerenkool](https://forum.fudiabetes.org/u/Boerenkool)
#### Post date: [November 7, 2017, 7:23pm UTC](https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579/14 "2017-11-07T19:23:26Z")
That’s insane!
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### Author:  [@docslotnick](https://forum.fudiabetes.org/u/docslotnick)
#### Post date: [November 7, 2017, 7:24pm UTC](https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579/15 "2017-11-07T19:24:46Z")
@Boerenkool Ah, you seem to be getting a sense of how our government works over here. 😜
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### Author:  [@Boerenkool](https://forum.fudiabetes.org/u/Boerenkool)
#### Post date: [November 7, 2017, 7:57pm UTC](https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579/16 "2017-11-07T19:57:36Z")
Sometimes I feel I have a better understanding of how your government works than of that organization in Brussels that rules Europe 😜
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### Author:  [@Michel](https://forum.fudiabetes.org/u/Michel)
#### Post date: [November 7, 2017, 8:10pm UTC](https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579/17 "2017-11-07T20:10:16Z")
> [@docslotnick](#):
>
> I didn’t want to make public my excursion to 270 😭. The 22u correction I took brought it down in a few hours
Heh. My son gets these every week ☹ Last Sunday we blew through 30U on one peak that lasted all afternoon. 30U is darn close to his TDD.
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### Author:  [@Michel](https://forum.fudiabetes.org/u/Michel)
#### Post date: [November 7, 2017, 9:15pm UTC](https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579/18 "2017-11-07T21:15:55Z")
15 posts were split to a new topic: [FDA, drug approval and state bureaucracies](https://forum.fudiabetes.org/t/fda-drug-approval-and-state-bureaucracies/2584)
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### Author:  [@Boerenkool](https://forum.fudiabetes.org/u/Boerenkool)
#### Post date: [November 7, 2017, 8:44pm UTC](https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579/20 "2017-11-07T20:44:55Z")
Terrifying. That’s close to my TDD too. I would be scared if it took that much insulin to bring down a peak.
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### Author:  [@Michel](https://forum.fudiabetes.org/u/Michel)
#### Post date: [November 7, 2017, 8:55pm UTC](https://forum.fudiabetes.org/t/what-happens-to-your-cgm-data-for-the-extra-hour-on-daylight-savings-time-fallback-day/2579/24 "2017-11-07T20:55:04Z")
> [@Boerenkool](#):
>
> I would be scared if it took that much insulin to bring down a peak.
Even though it happens to us often, I am still worried every time. And frustrated: when the 3rd correction in 4 hours fails and we go up to 10U in one injection with no food coming, I can’t help checking his CGM follow app every 5 minutes and hoping that his sensor won’t fail in the next hour.
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