# Mystery CGM Squiggles **URL:** \ **Category:** C/GM\ **Created:** [September 4, 2025, 2:12pm UTC](https://forum.fudiabetes.org/t/mystery-cgm-squiggles/15439 "2025-09-04T14:12:35Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![cogdog](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/cogdog/32/5436_2.png) [@cogdog](https://forum.fudiabetes.org/u/cogdog)\ **Post date:** [September 4, 2025, 2:12pm UTC](https://forum.fudiabetes.org/t/mystery-cgm-squiggles/15439/1 "2025-09-04T14:12:35Z")
The ongoing unexplained patterns of T1D. Or just me. I wake at 6:45am for coffee with my wife. My tandem indicates a 3.7 red earning with flat trend. Rather than rushing for dextrose, I’m up at 7 and turn off the pump while in shower. Right after I turn it on and see on its own it’s poked up to 5.3, than drops slightly (sloppy scribbling with iPhone markup pens). ![IMG_6787](https://canada1.discourse-cdn.com/flex030/uploads/fudiabetes/original/2X/3/300b69418cb5b9b505ed3d8727983c85f275db62.jpeg) not sure at all what would spawn a small uptick with no food taken. Coffee? (Only with Splenda). Or is this just the variable accuracy of measurement. Living diabetic is always something to ponder every day. Up, down, down, up… ---
**Author:** ![allison](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/allison/32/10718_2.png) [@allison](https://forum.fudiabetes.org/u/allison)\ **Post date:** [September 4, 2025, 4:41pm UTC](https://forum.fudiabetes.org/t/mystery-cgm-squiggles/15439/2 "2025-09-04T16:41:42Z")
It’s likely just CGM variation. Mine does that too. ---
**Author:** ![needlesandmath](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/needlesandmath/32/10272_2.png) [@needlesandmath](https://forum.fudiabetes.org/u/needlesandmath)\ **Post date:** [September 4, 2025, 4:49pm UTC](https://forum.fudiabetes.org/t/mystery-cgm-squiggles/15439/3 "2025-09-04T16:49:45Z")
If the rise is during/after the shower, I get it too. I’ve had it with the G6 and G7, but fingersticks also sometimes bounce high then low for a while after I shower, so I don’t know whether it’s a real phenomenon or sensor-based. I just ignore the readings for 10 minutes or so until it settles. ---
**Author:** ![Boerenkool](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/boerenkool/32/6307_2.png) [@Boerenkool](https://forum.fudiabetes.org/u/Boerenkool)\ **Post date:** [September 4, 2025, 5:46pm UTC](https://forum.fudiabetes.org/t/mystery-cgm-squiggles/15439/4 "2025-09-04T17:46:34Z")
Could this be a compression low with the sensor overshooting after wake up? Another thing I experience occasionally are phantom spikes that occur when I move after having been in a relatively motionless state for a long time, like when I stand up from a chair after reading a book or when I get out of bed (while not having slept on my sensor arm). I wonder if the sudden movement causes a temporary disturbance in the interstitial fluid that messes with the sensor readings. ---
**Author:** ![mike\_g](https://avatars.discourse-cdn.com/v4/letter/m/34f0e0/32.png) [@mike\_g](https://forum.fudiabetes.org/u/mike_g)\ **Post date:** [September 4, 2025, 6:06pm UTC](https://forum.fudiabetes.org/t/mystery-cgm-squiggles/15439/5 "2025-09-04T18:06:24Z")
Showers will often cause the CGM to falsely indicate a short term rise (and subsequent fall). May have something to do with skin moisture? I too have seen that. ---
**Author:** ![RachelMaraii](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/rachelmaraii/32/12439_2.png) [@RachelMaraii](https://forum.fudiabetes.org/u/RachelMaraii)\ **Post date:** [September 4, 2025, 9:59pm UTC](https://forum.fudiabetes.org/t/mystery-cgm-squiggles/15439/6 "2025-09-04T21:59:18Z")
I’d say it was the shower too – that always happens to me! Like needlesandmath, I’ve also learned to ignore it for a couple more readings. I wait to reconnect until it’s gone back to normal, or else Control-IQ thinks I’m headed for the moon and auto-boluses. ---
**Author:** ![cogdog](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/cogdog/32/5436_2.png) [@cogdog](https://forum.fudiabetes.org/u/cogdog)\ **Post date:** [September 4, 2025, 10:26pm UTC](https://forum.fudiabetes.org/t/mystery-cgm-squiggles/15439/7 "2025-09-04T22:26:05Z")
Hah I never heard about the shower effect. And I do enjoy my water hot. It was not much of a rise to generate a dose. ---
**Author:** ![jim26](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/jim26/32/9780_2.png) [@jim26](https://forum.fudiabetes.org/u/jim26)\ **Post date:** [September 5, 2025, 3:15am UTC](https://forum.fudiabetes.org/t/mystery-cgm-squiggles/15439/8 "2025-09-05T03:15:47Z")
> [@cogdog](#): > > extrose, I’m up at 7 and turn off the pump while in shower. Right after I turn it on and see on its own it’s poked u yep - 100% the shower. ---
**Author:** ![RachelMaraii](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/rachelmaraii/32/12439_2.png) [@RachelMaraii](https://forum.fudiabetes.org/u/RachelMaraii)\ **Post date:** [September 5, 2025, 4:05am UTC](https://forum.fudiabetes.org/t/mystery-cgm-squiggles/15439/9 "2025-09-05T04:05:23Z")
> [@cogdog](#): > > It was not much of a rise to generate a dose. I think maybe I take too long of showers 😂 ---
**Author:** ![TomH](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/tomh/32/9063_2.png) [@TomH](https://forum.fudiabetes.org/u/TomH)\ **Post date:** [September 5, 2025, 12:58pm UTC](https://forum.fudiabetes.org/t/mystery-cgm-squiggles/15439/10 "2025-09-05T12:58:31Z")
@cogdog My apologies if you already know this (looked at your profile and it says you’ve been a T1 for much longer than I), but based on the question, I’m assuming you’re asking for comment, others may benefit as well. If the low is consistent and presumably without carbs ingested, sounds like your basal is set slightly too high; presuming your pump allows setting basal rates hourly, change nothing but that by lowering your basal rate a bit; determine the time to start/stop the new rate by looking at several days data and picking the time your BG starts going lower and set the new basal rate an hour (+/-) before that time. Don’t forget to reinstate your normal basal rate for an appropriate time, possibly an hour (+/-) prior. Use those settings for 2-3 days. If it works, great; if not adjust the basal rate a slight amount up or down or the time it starts earlier/later as indicated by the BG, then test again for few days. Repeat as needed. The rise indicated, if consistent, could be the coffee or FOTF (Feet On The Floor), both are common. The only real way to know is get up and don’t have the coffee (I know, “What? The elixir of life?”). If it rises its probably an FOTF response. If it rises sufficiently, then dose for the FOTF based on your sensitivity and ICR. If BG doesn’t rise, then try having the coffee and dose for it based on the BG rise level, insulin sensitivity, and ICR; this needs to be done for a few days with no other changes. If you’re like me, the 2-3 days is a pain, like needing to bolus 15-30 min prior to meals…but if you want a flat level, that’s the cost. Again, sorry if I’m talking to someone that knows and does already! If so, I hope some newly dx’d person reads this and learns… ---
**Author:** ![cogdog](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/cogdog/32/5436_2.png) [@cogdog](https://forum.fudiabetes.org/u/cogdog)\ **Post date:** [September 5, 2025, 2:27pm UTC](https://forum.fudiabetes.org/t/mystery-cgm-squiggles/15439/11 "2025-09-05T14:27:48Z")
Thanks Tom, I claim no expertise at all here, learning as I go. And this is my first year on a loop set up. My diabetes educator and I make adjustments too, not only basal rate, but the insulin/carb ratio is where we have fine tuned. I’m checking with him today as this week I’ve been seeing more of the night drops to below 3.7, and using sleep mode. The other issue is that hardly any 2-3 days are strictly the same! ---
**Author:** ![cogdog](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/cogdog/32/5436_2.png) [@cogdog](https://forum.fudiabetes.org/u/cogdog)\ **Post date:** [September 5, 2025, 2:30pm UTC](https://forum.fudiabetes.org/t/mystery-cgm-squiggles/15439/12 "2025-09-05T14:30:09Z")
I can’t chalk last night to a 3am shower! Levels dropped to below 4 and rebounded on its own to 10? We were told in camp back in the 70s of the Somogyi effect. ![IMG_6800](https://canada1.discourse-cdn.com/flex030/uploads/fudiabetes/original/2X/0/0c30be849aa2e65eaeb76ecd36b209a28c097105.jpeg) ---
**Author:** ![ClaudnDaye](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/claudndaye/32/5_2.png) [@ClaudnDaye](https://forum.fudiabetes.org/u/ClaudnDaye)\ **Post date:** [September 5, 2025, 2:48pm UTC](https://forum.fudiabetes.org/t/mystery-cgm-squiggles/15439/13 "2025-09-05T14:48:48Z")
Insulin sensitivity factor (ISF), also known as correction factor, is also a contributor if your experiencing any roller coaster effects. If the ISF is set too high, you’ll get too little insulin, and be high longer….if it’s set too low, you’ll get too much insulin and see more lows. The corrections due to the ISF being off either way causes the roller coaster effect, if that’s an issue you are experiencing. ---
**Author:** ![cogdog](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/cogdog/32/5436_2.png) [@cogdog](https://forum.fudiabetes.org/u/cogdog)\ **Post date:** [September 5, 2025, 3:03pm UTC](https://forum.fudiabetes.org/t/mystery-cgm-squiggles/15439/14 "2025-09-05T15:03:09Z")
That’s true! So on the Tandem you have basal, correction factor and insulin to carb ratio all to factor in, and while conceptually I understand them, the interplay is complex! ---
**Author:** ![TomH](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/tomh/32/9063_2.png) [@TomH](https://forum.fudiabetes.org/u/TomH)\ **Post date:** [September 6, 2025, 12:19pm UTC](https://forum.fudiabetes.org/t/mystery-cgm-squiggles/15439/15 "2025-09-06T12:19:19Z")
@cogdog You’re right, the daily changes can have significant effect! And most of us have probably experienced the “same thing different result”, I know I have! It’s not every time, not even every other time, but often enough to be frustrating. I’ve read there are some 40+ factors that can vary the result, so it’s sometimes difficult at best to adjust. It isn’t easy, that’s for sure. All we can do is try our best and deal with the result…sometimes I fly off the off the handle and wonder what did wrong (usually going high, but sometimes low) even though I know I’ve done what I could. If it helps, talking with your PCP/Endo/etc. seems a good approach to resolution, it may not resolve it, but gives you ideas you may not have considered! ---
**Author:** ![jim26](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/jim26/32/9780_2.png) [@jim26](https://forum.fudiabetes.org/u/jim26)\ **Post date:** [September 6, 2025, 1:57pm UTC](https://forum.fudiabetes.org/t/mystery-cgm-squiggles/15439/16 "2025-09-06T13:57:17Z")
Another comment on showers, I think it also activates the insulin faster. If I’m running high give a correction and jump in the shower, it seems to drop my bs quicker. ---
**Author:** ![Beacher](https://avatars.discourse-cdn.com/v4/letter/b/a6a055/32.png) [@Beacher](https://forum.fudiabetes.org/u/Beacher)\ **Post date:** [September 6, 2025, 2:28pm UTC](https://forum.fudiabetes.org/t/mystery-cgm-squiggles/15439/17 "2025-09-06T14:28:10Z")
> [@Boerenkool](#): > > phantom spikes … when I stand up from a chair after reading a book or when I get out of bed Both those exact situations make me go DOWN, whereas nearly everyone else says they go UP. [Beacher stamps feet] “Why am I _different_?!” ---
**Author:** ![needlesandmath](https://yyz2.discourse-cdn.com/flex030/user_avatar/forum.fudiabetes.org/needlesandmath/32/10272_2.png) [@needlesandmath](https://forum.fudiabetes.org/u/needlesandmath)\ **Post date:** [September 6, 2025, 2:46pm UTC](https://forum.fudiabetes.org/t/mystery-cgm-squiggles/15439/18 "2025-09-06T14:46:35Z")
Yes, this is how I usually handle breakfast. Bolus, long wait, eat, shower. Mostly flat line.