CGM Data on Smart Watch while Surfing

One of the most frustrating parts of life to adjust to after diagnosis with type 1 diabetes three years ago was surfing. Nothing burns carbs like chasing waves for hours and keeping my blood sugar in range was difficult. I battled scary low blood sugars during and after long sessions. When trying to carb load presurf to keep my BG up I would often feel sluggish in the water due to high sugars and even tested positive for ketones after a few carb overloads. I did try a Dexcom G4 Continuos Glucose Monitor (CGM) while I was getting used to taking over for my lazy pancreas but its signal would disconnect from the receiver every time I paddled out and sensors would fall off in the water, so I eventually ditched it.

Now, over two years later I am giving a CGM another shot.

Continuous glucose monitoring technology has come a long way in two years. Taking advantage of bluetooth and data cloud technologies and the impatience of a few T1D parents, it is now possible to monitor CGM data on your smart phone and smart watch. These impatient parents, also known as #Wearenotwaiting and Project Nightscout grew fed up with regulatory limitations slowing down the advancement of diabetes tech and took matters into their own hands. They hacked together CGM in the cloud, an open source system that stores CGM data in the cloud then transmits it to a custom web page and/or a bluetooth capable device such as a smart watch. Now parents of children with T1D can monitor their child’s BG from anywhere and active T1Ds such as myself can view current blood sugar data and trends right from our wrist. Oh what a time to be alive!

Once I learned of these exciting advancements in CGM tech I began researching ways I could harness this technology to help me perform better in my life’s passion, surfing. After months of research I have found a set up that works and after two weeks of tests I am ready to share my experiment with you. Here is how I monitor my Dexcom CGM data on my smartwatch while in the water and how you can too!

Step 1: CGM – Dexcom G5

First things first we need a Continuous Glucose Monitor. I chose the G5, Dexcom’s latest product because it allows you to send blood sugar data directly to a smart phone eliminating the need for the Dexcom receiver, reducing the amount of devices required for operation. There are other CGM’s with which this setup is possible but the G5 is the most advanced and easiest to set up from what I understand. Check out this chart from Nightscout to see if your CGM is capable of transmitting to a smart watch.


One of my biggest hurdles in this experiment was finding a site on my body to place the sensor where it would not interfere with surfing and be safe from ripping off in the water. When I previously used the Dexcom G4 I wore it on the backs of my arms or abdomen which proved to be horrible spots for surfing as they would constantly rip off in the water or get in the way of laying on the board.

When researching ideal sites, few suggested wearing the sensor on the leg but that is exactly where I found the best spot to be. I insert my sensor on my upper, outer thigh, right about where my pants pocket would be. I’ve found I have just enough fat there to insert the device with minimal pain and the sensor sits just far enough to the outside of my thigh so I am not laying on it while on my board. I shave the body hair around the site and so far have had no problems with the sensor adhesive coming unstuck in the water. I do plan to use OpSite FlexFix waterproof medical tape in the future to make sure the sensor stays in place in heavy surf.


Step 2: Smart Watch – Pebble Time

There are a few smart watches capable of displaying CGM data, Android Wear, Apple Watch and the Pebble series as well as a few others. There are benefits to each, if you have an Android phone Android Wear could be the way to go. For iPhone users such as myself the Apple Watch is a good choice especially since the Dexcom mobile app supports the Apple Watch eliminating the need to set up Nightscout. But the Apple Watch and most Android watches require a waterproof case to survive long submerges unlike the Pebble Time smart watch which is waterproof to 50 meters straight out of the box. (Update 9/17/16: Apparently the new Apple Watch is waterproof!) Thanks to the fact it relies on traditional side buttons rather than a pressure sensitive touch screen. Not to mention the Pebble Time is considerably cheaper than the Apple Watch at only $70 on Amazon!

*Some insurance providers may cover your smart watch as a dura-medical device! Ask your doctor for a DMD prescription and contact your insurance provider!

Step 3: Setting up the Watch with Dexcom App

Setting up your Pebble Time with the Dexcom app is simple! Just download your desired watch face designed by Nightscout, change a few settings and BAM you are monitoring your BG on your watch.

For Pebble and other watch set up instructions visit the Nightscout site.

Step 4: Waterproofing

The main technical limitation to this set up is the fact that a smart phone must always be a part of the equation. The signal chain goes like this; the Dexcom sensor reads blood sugar levels then transmits the data to the phone where it’s then transmitted to the watch via bluetooth, meaning the phone and watch must stay within bluetooth range of each other. Modern smart phones’ bluetooth range average around 30 feet (10 meters) which means the phone must stay with me while in the water.

Dexcom is apparently working on eliminating the need for a smart phone by having the transmitter send data straight to the watch but there is currently no info on when we might see that functionality. 

Taking my phone surfing scared the crap out of me.The Dexcom transmitter and Pebble watch are good to go in the water but I had to figure out a way to securely waterproof my phone and comfortably wear it out into the line up.

There are tons of waterproof iPhone cases on the market and I was overwhelmed at first. After reading countless negative reviews on Life Proof cases, Otterboxes, etc. I decided I wasn’t going to rely on a solid, full time case to keep my phone dry. I turned to more reliable (and cheaper) bag type, diving cases. I landed on this Vanksy Dry Bag and after half a dozen test runs it is holding up nicely. (I plan on experimenting with other dry bag style phone cases as it seems the Vanksy may not hold up in the long run, especially after heavy use on my upcoming trip to California). For added security I place my phone in a couple zip lock bags before putting it in the dry bag.

Once my phone was waterproof I had to find a way to comfortably carry it with me in the water. Throwing it in my boardshort pocket didn’t work and a traditional fanny pack proved uncomfortable. I stumbled on these neoprene, strapless running belts that work perfectly. No strap means no discomfort while laying on my board and the tight fit keeps my phone firm to the small of my back.


Running belt and dry bag case with phone in zip locks. The key clip is a handy extra feature in case the case gets pulled from the belt.

side back

Conclusion, Observations and Future Modifications

So to recap;

Dexcom G5 CGM with sensor placed on my upper thigh + iPhone in zip lock bags and dry bag case in a neoprene running belt + Pebble Time waterproof smart watch = CGM data on my wrist while surfing! 

I am still a little shocked that this is even possible! So far everything has been working well. The only issue I have faced is the watch losing signal from the app while in the water which is easily fixed by restarting the Pebble app but impossible to do from the water. I am hoping a new, super reliable case will allow me to safely access my phone in the line up and hopefully upgrading to a newer iPhone will eliminate this issue (I am currently using an iPhone 5c).

In the future I want to find the perfect waterproof case and maybe find a way to strap it to my upper leg instead of my back, as the running belt slips up a bit when thrashing around in the water.

A huge thanks to #Wearenotwaiting for making this set up possible as well as Chris Kroger and Wendy Morgan for turning me onto this technology.

Have any questions or feedback about this set up? Drop a comment below!

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