Swimming with Dexcom

Hi there,
just started using CGM. I got the Dexcom G4 (I live in Belgium - EUROPE) and I'm real happy with the device. I'm a little confused though about what to do in water. I would like to go for a swim this morning. Do I put Tegaderm tape all over the sender or is it okay for the sender to get wet? I do shower with it (I tape the sender but make a hole in it so the sender is not blocked).
Can someone help me out? don't want to ruin the sender...

Hi Cathy, the sender/transmitter is waterproof so you don't need to put tape on it. The receiver is not waterproof so mustn't get wet though.

Hi Cathy,
I swim every day with the Dexcom. Keep in mind that while you are in the water unless the sensor (transmitter aka sender) is on your arm the Dexcom will not get readings. Or at the most you will get very little intermittant signal to the receiver. I put the receiver in a ziploc bag and leave it at the side of the pool. The sender is waterproof, I do not tape over it to avoid water and I spend more than an hour in the pool at a time.
Good luck, I too am really happy with the device.

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Thank you so much for the advice. I didn't read it until I came back. So I taped the whole sender, which wasn't necessary apparently. How about if I would put the receiver in a waterproof bag and wear it around my neck? Would it give me readings?
I would love to put the sensor on my arm. Do you put in on your under or upper arm, Clare?

Hi Cathy,
My sensor is on my upper arm in the middle, vertically about 2 inches below where the shoulder bends.
I don't think putting the receiver in a waterproof bag will have much of an effect on the signal in the water. I swim laps and spend an hour in the pool just about every day. The only time I have gotten any signal is when it was on my arm. Otherwise the water does not allow the signal to travel very well. I just leave the receiver in a waterproof bag at the side of the pool. So that when I make turns, my arm is out of the water. The receiver only checks for a signal once every 5 minutes. It does not search continuously so if you miss on of those 5 minute time points it will wait til the next time point. After a few missed time points you will get the lack of signal indicator.

thanks for letting me know. I'll try it out!

Hi Clare,

I had my first swim with the Dexcom. I put the receiver in a watertight surfpack underneath my rubber cap. I think it was packed too well, because it didn't give me any readings at all.
We gave it a second try: my husband walked beside me while I was swimming, holding the receiver. I swam 4 more laps, but there were no readings. Maybe I didn't try hard enough? (I had a 46 reading on my glucometer, making me come out of the pool to treat the low and had not much energy left).

Hi Cathy,
I swam last night too. But I always just leave the receiver in a plastic bag at the end of the pool. My sensor is currently on my thigh and I know I am not going to get any readings so I just plan accordingly. I check before I get in the pool. I swam 1/2 mile, then I got out of the pool and kept checking the receiver, once it got a reading after about 3 minutes and it was 118 I knew I was fine to finish the next 1/2 mile. This sensor is on day 8 and I have only missed 1 day of swimming but I have never gotten a reading while in the pool. Since I am on MDI anyway I can time my swims to when my basal is fading so ~12 hours. One thing you can do is check exactly what time you started the sensor - go to settings, device info, and the first thing you will see is insertion time, mine says 2:26 pm. So I know that it will check at 2:31, 2:36, 2:41 etc. If the sensor is on my arm, and I make sure I time my laps properly I have had hour long swims where I have only missed a few time points. I always bring juice and skittles and just leave them at the end of the pool with the receiver. But it's a work in progress and I am learning all the time. Nice that your husband will even go to the pool, mine doesn't even know where it is.

I have heard of some guy swimming with his reciever in a waterproof back taped somehow to his swimsuit and the sensor was on his stomach, he did this just to see what his readings were during a swim workout..i think it might be possible to get readings, now this was with the 7+, but i would think it would be better with the G4. I was told that the sending signal for the transmitter was similar to a bluetooth signal that would go 10feet..so if you try the water proof bag, thing again, try to get it closer to the location of your transmitter, and see what happens

The Dex transmitter is designed to transmit radio frequency waves through the air. To transmit through water (also known as sonar) requires a much different radio signal frequency, transmitter, and receiver. There is no benefit, and some needless risk, to bring the Dex receiver with you as you swim.

Swimming is such great exercise, it’s well worth missing a few readings provided you take other precautions such as staging fast acting glucose poolside.

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The reason why I want my readings, is that I could swim without worrying about my BG. If the Dexcom would do the trick, it would warn me when a low is coming up. That's why I want to try it out.


thank you so much for sharing your thoughts Clare.

I completely understand. And I hope that you can work out some way to get what you want. When I first posed the question http://www.tudiabetes.org/group/dexcomusers/forum/topics/swimming-laps-and-the-g4
I only got a few responses but most of them fell in to the "the signal will not travel through the water camp".

This was my response to myself about swimming laps

I went swimming with the G4 several times a day for a fortnight last July around a yacht in the Med with the receiver hung up in a waterproof bag on deck and it caught the vast majority of my readings as I swam around the boat and bays. The sensor was attached to my tummy but I was wearing a bikini so is it possible that a swimsuit would hamper the transmission? Just a thought.....

Hi there!

we went to the pool again yesterday. Thanks to you, I knew where to find the exact time I started my sensor, so I knew when it would check. I made sure not to miss that many points and it worked great! lost only 10 min. Thank you so much for your advice!

Yay I am so happy this worked for you. Swimming is such great exercise and the dex is so helpful when it works. Congrats on your success and enjoy the pool.

Love to read about your swimming laps! It really is a clean all-body exercise! I am now part of a Masters Swim Club and swimming about a mile 3x per week. I am an experienced lap swimmer but this is a bit more than my usual. I want to be challenged so that I can prepare to swim a mile under 40 minutes (I’m at 42.5 now!)
However, I am seeing a LARGE spike in my blood sugar immediately after I stop my laps. I assume this is an adrenaline response but my wife and I are concerned I may be pushing myself a bit too much.
I would appreciate anyone else’s comments on this effect in long aerobic exercise response. I have been Type 1 for 28 years now.