Effect of daily shower on BG

After I shower, my BG drops significantly. I’m on a t-slim pump and using DexCom G6. I’m not on Control IQ. I do cover the infusion set while showering. 10-15 minutes post shower, my BG starts dropping. I’ve had drops of 80 points and some “double arrows” down from the sensor. This happens every time I shower. It’s driving my spouse and me nuts. My NP says she’s never heard of this. It can take up to an hour for my BG to level out afterward. Anyone else experience this? How do you cope with it? I’ve been T1 for 62+ years and this has been happening in the last 3-4 months. (Note: I’m not using extremely hot water in the shower; my skin is definitely not red post shower, for example)

That’s really weird. I have a tandem and had a mini med for many years. I don’t even cover my site. My sugar doesn’t change at all. It might just be temperature related.
Maybe you can eat breakfast before your shower and perhaps pull back on your morning bonus.

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I use a G6 and t:slim (with Control-IQ) and have not seen that happen to me.

I disconnect the pump and leave it on the vanity … and don’t even bother to cover the infusion set.

A couple of thoughts:

  1. Do you check BG with a finger stick to see if it is a real drop or an artifact?

  2. Has this all been with one transmitter? I wonder whether the sensor to transmitter contact is a little “iffy” or whether the transmitter is not fully sealed and gets a little water or moisture in it. The duration of the effect seems consistent with something drying slowly.

Maybe someone else will have much better ideas, but those are my thoughts …

Good luck!


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I know a whole bunch of people on another site that have said their BG drops with hot showers, one even purposely takes hot showers when she needs her BG level to drop.

Mine on the other hand increases drastically, 60 points in 20-30 minutes of a hot shower. I have to take lukewarm showers as otherwise I feel horrible. Even lukewarm showers my BG level can increase. I always try to take my showers in the evening as I am least affected and once in a while I can even drop a little.

This is really only a problem when I wash my hair and it’s a longer shower, a short quick shower at lukewarm water and I am fine, my BG then only goes up a little.


Mine does the same. I always pre-bolus 6-8 units of humalog 30 minutes before my daily hot morning shower or will go up between 60 - 70 points of BG. If I don’t pre-bolus, then not only do I have this huge rise in BG but it takes 4 - 5 hours to work it back down and then it is lunch time which requires even a larger pre-bolus. Shower pre-bolus allows me to do a normal lunch pre-bolus so really flattens out the curve for the day.

My insulin takes 26 minutes before it starts dropping my BS. So bolus for meals is 15 minutes before eating, but before shower pre-bolus is 30 minutes to give my BS a chance to start to drop a little before shower as hot shower spikes glucose almost immediately.

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Same here. I usually check bg before the shower and take a glucose tablet or a few jellybeans beforehand. I must admit I look forward to the few jellybeans.


Have you cross-checked the G6 reading against a fingerstick before and after?

I and others have found that going from a resting position to exercise or anything that increases blood flow (like warm water in a shower), can cause a “stale” bg due to “stale nonmoving interstitial fluid” to rapidly change to a more current reading.

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I neglected to mention in my original post that I have cross checked the reading from the G6 with fingersticks. Most times I do not have to treat the BG drop. My BG does level off after a bit, then stays in an acceptable range. It’s the drop that is aggravating! To address John’s question about transmitters—this has been happening with several transmitters. (I did experience an issue with a G5 transmitter that wasn’t completely snapped in once, but that gave intermittent readings, not falling BGs.) A good thought however!

I tend to shower after eating breakfast; I wait for the upward spike to start before showering. Anything to try to thwart the drastic drop! I don’t want to consume extra carbs before my shower to counteract things bc my BG levels out on its own within an hour or less.

One other note—I’m seeing a NP who specializes in endocrinology/diabetes because my endo is on an extended leave of absence for illness. My endo will be back in August; am hopeful she has some ideas.

Thanks for all the comments and suggestions! This forum is wonderful!

I don’t know if this is of any help, but I have been a type 1 for 61 yrs with strict control and have never noticed a glucose change after my hot shower. I don’t use a pump. Sorry for what you are going through.

I don’t think it’s strange. Temperature is one of the known variables to affect blood sugar. I love long, HOT baths, and have to keep fruit snacks near the tub


Yes, hot water might affect it. It increases blood flow at the skin’s surface, and can speed up absorption.

But…it might also depend on when you are taking a shower.

Many (most?) people take their showers at the same time everyday. They have a routine.

For example, someone might take a shower every time after yard work. If they had a drop in BG, it would probably be from the yard work more than the shower. But since it is delayed, if they see it right after the shower, they might associate it with the shower instead of the yard work.

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Interesting. 30 years T1D, and I have never thought of this. I know that temperature can affect blood sugar, but it never occurred to me think about that in terms of the shower. Ha…never know what I’m going to learn on this forum! :slight_smile:


Are you showering just after waking up? My BG will often drop (sometimes significantly) as my body’s metabolism ramps up. I imagine if I showered at this time daily I might mistakenly attribute it to the shower.

I’ve just started on the Freestyle Libre, and had my first shower with it on. I was very surprised to see my sugar spike after the shower, and definitely felt a bit tired and like I needed a moment to catch my breath.

I’ve seen both drops and spikes. I shower after my workouts in the evening. My workouts are a mix of weights and walks/runs to keep the blood sugar balanced. Lately I’ve been doing the weights first which brings my numbers up and then doing my walks/runs after to bring it back down. I temp basal (~50%) before and during the workouts.

If my shower is quick, 5 min, my numbers drop (not double arrows but down). If I take a longer shower they’ll be starting to spike when I get out and check the screen. If I plug back in right then my spike will curve and start heading back down again in about 15 minutes. I attribute this to both the workout and the shower. I’m on BIQ not CIQ yet.

When I’ve done the reverse (run then weights), I have a tendency to spike by the end. The shower slows it and when I plug back in the warm tissue and the pumped muscles do help it start to curve back, but it takes longer 30-40 minutes.

I will not correct for above or below target in either situation because it usually comes back to target on it’s own. I have used showers to help speed up the absorption when I put a new set in and it’s not responding as fast as I want it to, but not often.

Same here. OP is lucky! I have to walk a mile+ on my treadmill to “recover” from my shower spike!

I joke that what I really have is showerbetes because it represents my largest spike of the day! :frowning:

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I was diagnosed T1 about 6 years ago and started insulin basal and bolus right away. There is only so much training an educator can give, and life experiences taught me how my body responds. The most frightening experience was stumbling out of the shower with my first blood sugar low. I’ve learned to make sure my BG is a little high before I shower. I wear a Dexcom now, but may fingerstick before showering just to be safe. I’ll never forget my first low and that awful introduction to diabetes unpredictability


I get a fake shower spike every day…the Dexcom goes up and then when I leave the shower it drops just as fast. I am assuming this is simply the sensor reacting to the heat
as the enzymatic reaction that the sensor uses to sense blood sugar will be affected by temperature. It does not appear to be a real change in BG. It does affect BG predictions in automated systems like Loop. It sees the fast drop and assumes there is downward momentum in BG, and thinks it will keep going down.

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My BG spikes after taking the shower not immediately maybe 30 minutes later. Since I usually shower in the morning I first blamed it on coffee whether caffeinated or even non-caffeinated as some people do spike from coffee. Then I assumed it probably simply was because the basal wasn’t delivered for a period of time and made sure I gave myself a basal or a bolus before I entered the shower. I still can’t figure out why I spike after a shower but I do. A perfect example of how we are all different when it comes to type 1 diabetes.

fcarli: You hit the nail on the head: we are all different even though we have the same diagnosis!