swimming with diabetes

Missing metrics in diabetes measurement by @DanaMLewis

by Dana Lewis

“May I ask what your A1c is?”

This is a polite, and seemingly innocuous question. However, it’s one of my least favorite questions taken at face value. Why?

Well, this question is often a proxy for some of the following questions:

  • How well are *you* doing with DIY closed loop technology?
  • How well could *I* possibly do with DIY closed loop technology?
  • What’s possible to achieve in real-world life with type 1 diabetes?

But if I answered this question directly with “X.x%”, it leaves out so much crucial information. Such as:

  • What my BG targets are
    • Because with DIY closed loop tech like OpenAPS, you can choose and set your own target.
    • (That’s also one of the reasons why the 2018 OpenAPS Outcomes Study is fascinating to me, because people usually set high, conservative targets to start and then gradually lower them as they get comfortable. However, we didn’t have a way to retrospectively sleuth out targets, so those are results are even with the amalgamation of people’s targets being at any point they wanted at any time.)
  • What type of lifestyle I live
    • I don’t consider myself to eat particularly “high” or “low” carb. (And don’t start at me about why you choose to eat X amount of carbs – you do you! and YDMV) Someone who *is* eating a lot higher or lower carb diet compared to mine, though, may have a different experience than me.
    • Someone who is not doing exercise or activity may also have a different experience then me with variability in BGs. Sometimes I’m super active, climbing mountains (and falling off of them..more detail about that here) and running marathons and swimming or scuba diving, and sometimes I’m not. That activity is not so much about “being healthy”, but a point about how exercise and activity can actually make it a lot harder to manage BGs, both due to the volatility of the activity on insulin sensitivity etc.; but also because of the factor of going on/off of insulin for a period of time (because my pump is not waterproof).
  • What settings I have enabled in OpenAPS
    • I use most of the advanced settings, such as “superMicroBoluses” (aka SMB – read more about how it works here); with a higher than default “maxSMBBasalMinutes”; and I also use all of the advanced exercise settings so that targets also nudge sensitivity in addition to autosensitivity picking up any changes after exercise and other sensitivity-change-inducing activities or events. I also get Pushover alerts to tell me if I need any carbs (and how many), if I’m dropping faster and expected to go below my target, even with zero temping all the way down.
  • What my behavioral choices are
    • Timing of insulin matters. As I learned almost 5 years ago (wow), the impact of insulin timing compared to food *really* matters. Some people still are able to do and manage well with “pre-bolusing”. I don’t (as explained there in the previous link). But “eating soon” mode does help a lot for managing post-meal spikes (see here a quick and easy visual for how to do “eating soon”). However, I don’t do “eating soon” regularly like I used to. In part, because I’m now on a slightly-faster insulin that peaks in 45 minutes. I still get better outcomes when I do an eating-soon, sure, but behaviorally it’s less necessary.
    • The other reason is because I’ve also switched to not bolusing for meals.
      • (The exceptions being if I’m not looping for some reason, such as I’m in the middle of switching CGM sensors and don’t have CGM data to loop off of.)

These settings and choices are all crucial information to understanding the X.x% of A1c.

Diabetes isn’t just the average blood glucose value. It’s not just the standard deviation or coefficient of variation or % time in range or how much BG fluctuates.

Diabetes impacts so much of our daily life and requires so much cognitive burden for us, and our loved ones. That’s part of the reasons I appreciate so much Sulka & his family being candid about how their A1C didn’t change, but the amount of work required to achieve it did (way fewer manual corrections). And ditto for Jason & the Wittmer family for sharing about the change in the number of school nurse visits before/after using OpenAPS. (See both of their stories in this post)

For me, my quality of life metric has always been first about sleep: can I sleep safely and with peace of mind at night? Yes. Then – how long can I safely sleep? (The answer: a lot. Yay!)  But over time, my metrics have also evolved to consider how I can cut down (like Sulka) on the amount of work it takes to achieve my ideal outcomes, and find a happy balance there.

As I mentioned in this podcast recently, other than changing my pump site (here’s how I change mine) and soaking and swapping my CGM sensors (psst – soak your sensor!), I usually only take a few diabetes-related actions a day. They’re usually on my watch, pressing a button to either enable a temp target or entering carbs when I sit down to eat.

That’s a huge reduction in physical work, as well as amount of time spent thinking/planning/doing diabetes-related things. And when life happens – because I get the flu or the norovirus or I fall off a mountain and break my ankle – I don’t worry about diabetes any more.

So when I’m asked about A1c, my answer is not a simple “X.x%”. (And not just for the reason I’m annoyed by how much judging and shaming goes on around A1c, although that influences it, too.) I usually remind people that I first started with an “open loop” for a year, and that dropped my A1c by X%. And then I closed the loop, which reduced my A1c further. And we made OpenAPS even better over the last four years, which reduced it further. And then I completely stopped bolusing! And got less lows…and kept the same A1c.

And then I ask them what they’d really like to know. :) If it’s a fellow person with diabetes or a loved one, we talk about what problems they might be having or what areas they’d like to improve or what behaviors they’d like to change, if any. That’s usually way more effective than hearing “X.x%” of an A1c, and them wondering silently how to get there or what to do differently if someone wants to change things. (Or for clinicians who ask me, it turns into a discussion about choices and behaviors and tradeoffs that patients may choose to make.)

Remember, your diabetes may (and will) vary (aka, YDMV). Your lifestyle, the phase of life you’re in, your priorities, your body and health, and your choices will ALL be different than mine. That’s not bad in any way: that’s just the way it is. The behaviors I choose and the work I’m willing to do (or not do) to achieve *my* goals (and what my goals are), will be different than what you choose for yours.

And that’s therefore why A1c is not “enough” to me as a metric and something that we should compare people on, even though A1c is the “same” for everyone: because the work, time spent, behavioral tradeoffs, and goals related to it will all vary.

Missing_metrics_@DanaMLewis

4 years DIY closed looping with #OpenAPS – what changed and what hasn’t

by Dana Lewis

It’s hard to express the magnitude of how much closed looping can improve a person with diabetes’ life, especially to someone who doesn’t have diabetes or live closely with someone that does. There are so many benefits – and so many way beyond the typically studied “A1c improvement” and “increased time in range”. Sure, those happen (and in case you haven’t seen it, see some of the outcomes from various international studies looking at DIY closed loop outcomes). But everything else…it’s hard to explain all of the magic that happens in real life, that’s made so much richer by having technology that for the most part keeps diabetes out of the way, and more importantly: off the top of your mind.

Personally, my first and most obvious benefit, and the whole reason I started DIYing in the first place, was to have the peace of mind to sleep safely at night. Objective achieved, immediately. Then over time, I got the improvements in A1c and time in range, plus reduction in time spent doing diabetes ‘stuff’ and time spent thinking about my own diabetes. The artificial pancreas ‘rigs’ got smaller. We improved the algorithm, to the point where it can handle the chaos that is everything from menstrual cycle to having the flu or norovirus.

More recently, in the past ~17 months, I’ve achieved an ultimate level of not doing much diabetes work that I never thought was possible: with the help of faster insulin and things like SMB’s (improved algorithm enhancements in OpenAPS), I’ve been able do a simple meal announcement by pressing a button on my watch or phone..and not having to bolus. Not worrying about precise carb counts. Not worrying about specific timing of insulin activity. Not worrying about post-meal lows. Not worrying about lots of exercise. And the results are pretty incredible to me:

We should be measuring and reducing user burden with AID in addition to improving TIR and A1c

But I remember early on when we had announced that we had figured out how to close the loop. We got a lot of push back saying, well, that’s good for you – but will it work for anyone else? And I remember thinking about how if it helped one other person sleep safely at night..it would be worth the amount of work it would take to open source it. Even if we didn’t know how well it would work for other people, we had a feeling it might work for some people. And that for even a few people who it might work for, it was worth doing. Would DIY end up working for everyone, or being something that everyone would want to do? Maybe not, and definitely not. We wouldn’t necessarily change the world for everyone by open sourcing an APS, but that could help change the world for someone else, and we thought that was (and still is) worth doing. After all, the ripple effect may help ultimately change the world for everyone else in ways we couldn’t predict or expect.

Ripple_effect_DanaMLewisThis has become true in more ways than one.

That ‘one other person’ turned into a few..then dozen..hundreds..and now probably thousand(s) around the world using various DIY closed loop systems.

And in addition to more people being able to choose to access different DIY systems with more pumps of choice, CGMs of choice, and algorithm of choice, we’ve also seen the ripple effect in the way the world works, too. There is now, thankfully, at least one company who is evaluating open source code; running simulations with it; and where it is out-performing their original algorithm or code components, utilizing that knowledge to improve their system. They’re also giving back to the open source diabetes community, too. Hopefully more companies will take this approach & bring better products more quickly to the market. When they are ready to submit said products, we know at least U.S. regulators at the FDA are ready to quickly review and work with companies to get better tools on the market. That’s a huge change from years ago, when there was a lot of finger pointing and what felt like a lot of delay preventing newer technology from reaching the market. The other change I’m seeing is in diabetes research, where researchers are increasingly working directly with patients from the start and designing better studies around the things that actually matter to people with diabetes, including analyzing the impact and outcomes of open source technology.

After five years of open source diabetes work, and specifically four years of DIY closed looping, it finally feels like the ripples are ultimately helping achieve the vision we had at the start of OpenAPS, articulated in the conclusion of the OpenAPS Reference Design:

OpenAPS_Reference_Design_conclusionIs there still more work to do? Absolutely.

Even as more commercial APS roll out, it takes too long for these to reach many countries. And in most parts of the world, it’s still insanely hard and/or expensive to get insulin (which is one of the reasons Scott and I support Life For A Child to help get insulin, supplies, and education to as many children as possible in countries where otherwise they wouldn’t be able to access it – more on that here.). And even when APS are “approved” commercially, that doesn’t mean they’ll be affordable or accessible, even with health insurance. So I expect our work to continue, not only to support ongoing improvements with DIY systems directly; but also with encouraging and running studies to generalize knowledge from DIY systems; hopefully seeing DIY systems approved to work with existing interoperable devices; helping any company that will listen to improve their systems, both in terms of algorithms but also in terms of usability; helping regulators to see both what’s possible as well as what’s needed to successfully using these types of system in the real world. I don’t see this work ending for years to come – not until the day where every person with diabetes in every country has access to basic diabetes supplies, and the ability to choose to use – or not – the best technology that we know is possible.

But even so, after four years of DIY closed looping, I’m incredibly thankful for the quality of life that has been made possible by OpenAPS and the community around it. And I’m thankful for the community for sharing their stories of what they’ve accomplished or done while using DIY closed loop systems. It’s incredible to see people sharing stories of how they are achieving their best outcomes after 45 years of diabetes; or people posting from Antartica; or after running marathons; or after a successful and healthy pregnancy where they used their DIY closed loop throughout; or after they’ve seen the swelling in their eyes go done; etc.

The stories of the real-life impacts of this type of technology are some of the best ripple effects that I never want to forget.

Scuba diving with a flash glucose monitor (Libre)

by Dana Lewis

Scuba_Flash_Glucose_Monitoring_DanaMLewisI just went scuba diving in Australia* at the Great Barrier Reef, and I took a flash glucose monitor (Libre) with me under the water.

WHAT! Yes, really. Scuba diving with a Libre. (Your mileage may vary, of course! The Libre receiver is not waterproof in of itself, and obviously not rated/tested for depth. I did some of that testing for myself. See below 😉 )

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Historically (and you can read more in this post for more detail on what else I do regarding pump, CGM, and everything else for scuba diving with diabetes and other diabetes devices),  I only had a CGM that did not work underwater, and did not work for around an hour after I went diving since it would get waterlogged.

A few months ago when Libre was FDA approved in the US, I paid cash out of pocket (for a receiver + 3 sensors) to try it to see how it did compared to my CGM.  For most purposes, a CGM still makes sense for me, because I rely on it for closed looping, and on its low and high glucose alarms.  But I know from previous dives and other water activities that my CGM doesn’t work well after a long time in (deep) salt water: I often get false-positive highs for an hour (or more) afterward.  So for this trip, I was thinking I would wear a Libre sensor for the dive trip, and just scan when I got out of the water, so I didn’t have to do a fingerstick test after every dive.

In the weeks leading up to our trip, I also saw a picture and heard rumblings of people going scuba diving and taking their Libre receiver under the water. I couldn’t find any details about it, though: What case? What depth? etc. ARGH.

So we decided to pick out a waterproof phone case and just give it a try during our trip. Worst case, we’d just ruin the receiver. Scott found this waterproof phone case/bag (<–Amazon affiliate link) and ordered it, and I packed it for the trip. Probably other similar phone cases would work, too – brand likely doesn’t matter, but you obviously would want a case that’s not going to leak, and should perform a leak test on it before you leave home.

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We did a “liveaboard” for 3 days and 2 nights (really, ~48 hours on the boat). There’s a transfer boat that takes you out to the “liveaboard”, which is essentially a floating hotel. When you get there, you’re allowed to do a snorkel session before lunch; the first dive briefing is after lunch, and you can then dive during the sessions (max 3 day dives total and 1 night dive) after that during your stay. All this detail to explain that we popped the Libre receiver in the waterproof bag and took it into the water with us when we went snorkeling. And it worked great! So that gave me the courage I needed to take it down during our first dive.

You can scuba dive with a CGM receiver in a waterproof bag

The waterproof case had a strap where you could wear it around your neck, which is what I did. That ended up being annoying occasionally (because the bag would float above you during the die, and sometimes got caught on my snorkel), but it worked. (For future trips I’d probably find a stretchy cord to attach it to my BCD where it was accessible but didn’t have to float or be hung around my neck.)

I wore two wetsuits (I get cold easily!), and even with two layers of wetsuit; the waterproof case; and you know, the water – I was still able to easily press the button on the Libre receiver through the bag, swipe it over my arm, and pick up a BG reading! It was super cool for it to work. The hardest part: finding the Libre sensor under 2 layers of wetsuit on my arm.

The first few dives were somewhat shallow – 9-12 meters of depth, but over the course of all my dives, I ended up testing it down to 16 meters. I also tested it on 9 total sessions – 1 snorkel, 2 morning sunrise dives, 2 night dives (whoa), and 4 daytime dives. The bag did fine throughout each submersion and never leaked.

We did 8 scuba dives in 48 hours, all with a CGM that worked in the water

I was also expecting the sensor to peel up, so I did four strips of flexifix tape (like I do to my CGM sensor) around the outside edges of the sensor. The tape itself didn’t end up peeling up, and the sensor stayed on just fine! (It probably helped that I wasn’t sunscreening the edges of the tape, since I was pretty much in 2 layers of wetsuit every time I was out in the water and in the sun.) If the sensor ripped out, that would have been a pain as the one I have is the original one approved in the US that requires a 12 hour warmup (ugh) – thankfully, that didn’t happen, and also thankfully, the day we got off the boat we heard that the Libre is now approved in the US for 14 day wear (instead of 10) and now only ONE hour warmup (yay!). That’ll make it nice and easy (if I get the updated sensors) for future dive trips if a sensor rips off.

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In terms of accuracy and sensor performance:

My first Libre sensor that I had tried at home a few months ago when we got it ran low pretty consistently, and ran REALLY low when my BG was normal. That drove me nuts and I was pretty sure that I wouldn’t want to rely on it the way some people do. So I was planning to not be able to rely on the numbers, and just use it for trends when diving. However, this second sensor (that I did all my scuba diving with) was spot on, even when high and low. I cross checked with finger sticks before and after the first dive, but quickly tailed off fingersticks (other than calibrating my CGM) for the most part, and was able to rely on Libre to double-check my CGM. (As expected, because of the waterlogging, the CGM ran falsely high, sometimes 100 mg/dL off, for about an hour after the dive.)

I left the Libre on even beyond the dive boat part of our trip, and it’s been spot on alongside my CGM (which is also spot on) compared to fingersticks.

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So to summarize my experience: Libre is great for scuba diving. I tested it down to 16 meters and was happy with how it worked underwater! I loved being able to check mid-dive and see my trends. I never had a low during my 8 dives in 48 hours, and I never worried about going low since I wasn’t diving “blind” to my BGs. I definitely plan to use this for future scuba diving trips, and would also consider using it for any beach/water-based activities. The convenience is worth (for me) paying out of pocket cash for a few sensors to be able to access my BGs easily during these activities.

Various views from our scuba diving trip

* One final note: Australia has some of the strictest diving laws in the world regarding your health. If you have type 1 diabetes, you have to have a very particular Australian dive medical form filled out before any company will let you dive. Now, many companies will tell you to just show up in Cairns and use the dive medical centers for a cheap and easy dive medical. HOWEVER: we called three of them in advance. One said “NOPE” out of hand to approving a (perfectly healthy) person with type 1, solely because that person (me) has type 1. The second wasn’t sure and asked us to email a full medical history to give us an opinion. They never responded to the email. The third didn’t answer phone or email. Ugh. So: my advice is, get the form, and go talk **in person** to your physician of choice about this and the necessary information needed to have a physician fill out this form. I stressed a lot about this; but once I handed in the special form along with the standard medical form everyone has to fill out – they didn’t say a word to me, ask me about diabetes, or prevent me from diving. So my advice is to go prepared with your form!

Scuba diving, snorkeling, and swimming with diabetes (and #OpenAPS)

by Dana Lewis

tl;dr – yes, you can scuba dive with diabetes, snorkel with diabetes, and swim with diabetes! Here’s what you need to know.

I meant to write this post before I left for a two-week Hawaii trip, and since I answered about a question a day on various platforms as I posted pictures from the trip, I really wish I had done it ahead of time. Oh well. :) I especially wish someone had written this post for me 2 years ago, before my first scuba dive, because I couldn’t find a lot of good information on the practicalities of good approaches for dealing with all the details of scuba diving with diabetes and an insulin pump and CGM and now closed loops. Scuba diving, snorkeling, and swimming with diabetes are actually pretty common, so here are a few things to keep in mind/tips from me, before diving (pun intended) into some explanations of what I think about for each activity diabetes-wise.

scuba_diving_with_diabetes_tips_water_activities_by_Dana_M_Lewis

General tips for water activities when living with diabetes:

  1. Most important: be aware of your netIOB going into the activity. Positive netIOB plus activity of any kind = expedited low BG. This is the biggest thing I do to avoid lows while scuba diving or snorkeling – trying to time breakfast or the previous meal to be a few hours prior so I don’t have insulin peaking and accelerated by the activity when I’m out in the water and untethered from my usual devices.
  2. Second most important: CGM sensor and transmitter on your body can get wet (shower, pools, hot tubs, oceans, etc.), but keep in mind it can’t read underwater. And sometimes it gets waterlogged from short or long exposure to the water, so it may take a while to read even after you get it above water or dry off. And, historically I’ve had sensors come back and the CGM will sometimes read falsely high (100-200 points higher than actual BG), so exercise extreme caution and I highly recommend fingerstick testing before dosing insulin after prolonged water exposure.
  3. Know which of your devices are waterproof, watertight, etc. Tip: most pumps are not waterproof. Some are watertight*. The * is because with usual wear and tear and banging into things, small surface cracks start showing up and make your pump no longer even watertight, so even a light splash can kill it. Be aware of the state of your pump and protect it accordingly, especially if you have a limited edition super special super rare DIY-loopable pump. I generally take a baggie full of different sized baggies to put pump/CGM/OpenAPS rig into, and I also have a supposedly waterproof bag that seals that I sometimes put my bagged devices into. (More on that below).
    1. And in general, it’s always wise to have a backup pump (even if it’s non-loopable) on long/tropical/far away trips, and many of the pump companies have a loaner program for overseas/cruise/tropical travel.
  4. Apply sunscreen around your sites/sensors because sunburn and applying or removing them hurts. However, as I learned on this trip, don’t do TOO much/any sunscreen directly on top of the adhesive, as it may loosen the adhesive (just surrounding the edges is fine). I usually use a rub sunscreen around the edges of my pump site and CGM sensor, and do the rest of my body with a spray sunscreen. And pack extra sites and sensors on top of your extras.

Why extras on top of your extras? Because you don’t want to have a vacation like I did where I managed to go through 5 pump site catastrophes in 72 hours and run out of pump sites and worry about that instead of enjoying your vacation. Here’s what happened on my last vacation pump-site wise:

  • Planned to change my site the next morning instead of at night, because then I would properly use up all the insulin in my reservoir. So I woke up, put in a new pump site (B) on my back hip, and promptly went off to walk to brunch with Scott.
  • Sitting down and waiting for food, I noticed my BG was rocketing high. I first guessed that I forgot to exit the prime screen on the pump, which means it wasn’t delivering any insulin (even basal). Wrong. As I pulled my pump off my waist band, I could finally hear the “loud siren escalating alarm” that is “supposed” to be really audible to anyone…but wasn’t audible to me outside on a busy street. Scott didn’t hear it, either. That nice “siren” alarm was “no delivery”, which meant there was something wrong with the pump site and I hadn’t been getting any insulin for the last hour and a half. Luckily, I have gotten into the habit of keeping the “old” pump site (A) on in case of problems like this, so I swapped the tubing to connect to the “old” site A and an hour or so later as insulin started peaking, felt better. I pulled site B out, and it was bent (that’s why it was no delivery-ing). I waited until that afternoon to put in the next pump site (C) into my leg. It was working well into dinner, so I removed site A.
  • However, that night when I changed clothes after dinner, site C ripped out. ARGHHHH. And I had removed site A, so I  had to put on another site (D). Bah, humbug. Throw in someone bumping a mostly-full insulin vial off the counter and it shattering, and I was in one of my least-pleased-because-of-diabetes moods, ever. It was a good reminder of how much a closed loop is not a cure, because we still have to deal with bonked sites and sites in general and all this hoopla.
  • Site D lasted the next day, while we went hiking at Haleakala (a 12.2 mile hike, which was amazing that neither my site or my sensor acted up!). However, on the third day in this adventure, I put on sunscreen to go to the beach with the whole family. When we came back from the beach, I went to remove my cover up to shower off sand before getting into the pool. As my shirt came over my head, I saw something white fly by – which turned out to be 4th pump site, flying around on the end of the pump tube, rather than being connected to my body. There went Site D. In went my fifth site (E), which I tackled down onto my body with extra flexifix tape that I usually use for CGM sensors because I. Was. Fed. Up. With. Pump. Sites!
  • Thankfully, site E lasted a normal life and lasted til I got home and did my next normal site change, and all is back to normal.

Lessons learned about pump sites: I repeat, don’t sunscreen too much on the adhesive, just sunscreen AROUND the adhesive. And pack extras, because I went through ~2 weeks of pump sites in 3 days, which I did not expect – luckily I had plenty of extra and extras behind those!

Now on to the fun stuff.

Scuba Diving with diabetes:

  • 2 years ago was my “Discovery” dive, where you aren’t certified but they teach you the basics and do all the equipment for you so you just do some safety tutorials and go down with a guide who keeps you safe. For that dive, I couldn’t find a lot of good info about scuba diving with diabetes, other than logical advice about the CGM sensor not transmitting under water, the receiver not being waterproof, and the pump not being waterproof. I decided to try to target my BG in advance to be around 180 mg/dl to avoid lows during the dive, and for extra safety eat some skittles before I went down – plus I suspended and removed my pump. Heh. That worked too well, and I was high in the mid-200s in between my two dives, so I found myself struggling to peel my wetsuit off in between dives to connect my pump and give a small bolus. The resulting high feeling after the second dive when my BG hadn’t re-normalized yet plus the really choppy waves made me sea-sick. Not fun. But actually diving was awesome and I didn’t have any lows.
    • Pro tip #1 for scuba diving with diabetes: If you can, have your pump site on your abdomen, arm, or other as-easy-as-possible location to reconnect your pump for between-dive boluses so you don’t have to try to get your arm down the leg of your wetsuit to re- and disconnect.
  • I decided I wanted to get PADI certified to scuba dive. I decided to do the lessons (video watching and test taking) and pool certification and 2/4 of my open water dives while on a cruise trip last February. Before getting in the pool, I didn’t do anything special other than avoid having too much (for me that’s >.5u) of netIOB. For the open water dives at cruise ports, I did the same thing. However, due to the excitement/exertion of the first long dive, along with having to do some open water safety training after the first dive but before getting out (and doing my swim test in choppy open water), I got out of the water after that to find that I was low. I had to take a little bit longer (although maybe only 10 extra minutes) than the instructor wanted to finish waiting for my BG to come up before we headed out to the second dive. I was fine during and after the second dive, other than being exhausted.
    • Pro tip #2 for scuba diving with diabetes: Some instructors or guides get freaked out about the idea of having someone diving with diabetes. Get your medical questionnaire signed by a doctor in advance, and photocopy a bunch so you can take one on every trip to hand to people so they can cover themselves legally. Mostly, it helps for you to be confident and explain the safety precautions you have in place to take care of yourself. It also helps if you are diving with a buddy/loved one who understands diabetes and is square on your safety plan (what do you do if you feel low? how will you signal that? how will they help you if you need help in the water vs. on the boat, etc.?). For my training dives, because Scott was not with me, I made sure my instructor knew what my plan was (I would point to my arm where my sensor was if I felt low and wanted to pause/stop/head to the surface, compared to the other usual safety signals).
  • This past trip in Hawaii I was finishing off a cold at the beginning, so at the end of the trip I started with a shore dive so I could go slow and make sure it was safe for me to descend. I was worried about going low on this one, since we had to lug our gear a hundred feet or so down to the beach and then into the water (and I’ve never done a shore dive prior to this). I did my usual prep: temp basal to 0 on my pump for a few hours (so it can track IOB properly) and suspend; place it and CGM and OpenAPS rigs in baggies in my backpack; and confirming that my BG was flat at a good place without IOB, I didn’t eat anything extra. We went out slowly, had a great dive (yay, turtles), and I was actually a little high coming back up after the dive rather than low. My CGM didn’t come back right away, so I tested with a fingerstick and hooked my pump back up right away and gave a bolus to make up for the missed insulin during the dive. I did that before we headed off the beach and up to clean off our gear.
    • Pro tip #3 for scuba diving with diabetes: Don’t forget that insulin takes 60-90 minutes to peak, so if you’ve been off your pump and diving for a while, even if you are low or fine in that moment, that missing basal will impact you later on. Often if I am doing two dives, even with normal BG levels I will do a small bolus in between to be active by the time I am done with my second dive, rather than going 3+ hours with absolutely no insulin. You need some baseline insulin even if you are very active.
  • While in Hawaii, we also got up before the crack of dawn to head out and do a boat dive at Molokini. It was almost worth the 5am wakeup (I’m not a morning person :)). As soon as I woke up at 5am, I did an “eating soon” and bolused fully for my breakfast, knowing that we’d be getting on the boat at 6:30amish (peak insulin time), but it’d take a while to get out to the dive site (closer to 7:30am), so it was better to get the breakfast bolus in and let it finish counteracting the carbs. I did, but still ran a little higher than I would have liked while heading out, so I did another small correction bolus about half an hour before I temped to zero, suspended, and disconnected and baggied/bagged/placed the bag up in the no-water-shelf on the boat. I then did the first dive, which was neat because Molokini is a cool location, and it was also my first “deep” dive where we went down to about ~75 feet. (My previous dives have all been no deeper than about ~45 feet.) Coming back onto the boat, I did my usual of getting the gear off, then finding a towel to dry my hands and do a fingerstick BG test to see what I was. In this case, 133 mg/dl. Perfect! It would take us almost an hour for everyone to get back on the boat and then move to dive spot #2, so I peeled down my wetsuit and reconnected my pump to get normal basal during this time and also do a small bolus for the bites of pineapple I was eating. (Given the uncertainties of accuracy of CGM coming out of prolonged water exposure, since they sometimes run 100+ points high for me, I chose not to have the loop running during this dive and just manually adjust as needed). We got to spot #2 and went down for the dive, where we saw sharks, eels, and some neat purple-tailed fish. By the end of the dive, I started to feel tired, and also felt hungry. Those are the two signs I feel underwater that probably translate to being low, so I was the first from our group to come up when we got back from the boat. I got on the boat, removed gear, dried hands, tested, and…yep. 73 mg/dl. Not a bad low, but I’m glad I stopped when I did, because it’s always better to be sure and safe than not know. I had a few skittles while reconnecting my pump, and otherwise was fine and enjoyed the rest of the experience including some epic dolphin and whale watching on the return boat ride back to the harbor!
    • Pro tip #4 for scuba diving with diabetes: You may or may not be able to feel lows underwater; but listening to your body and using your brain to pay attention to changes, about low or not, is always a really good idea when scuba diving. I haven’t dived enough  (7 dives total now?) or had enough lows while diving to know for sure what my underwater low symptoms are, but fatigue + hunger are very obvious to me underwater. Again, you may want to dive with a buddy and have a signal (like pointing to the part of your body that has the CGM) if you want to go up and check things out. Some things I read years ago talked about consuming glucose under water, but that seems above my skill level so I don’t think I’ll be the type of diver who does that – I’d rather come to the surface and have someone hand me from the boat something to eat, or shorten the dive and get back on the boat/on shore to take care of things.

All things considered, scuba diving with diabetes is just like anything else with diabetes – it mostly just takes planning ahead, extra snacks (and extra baggies) to have on hand, and you can do it just like anyone else. (The real pain and suffering of scuba diving in my opinion comes not from high or low BGs; but rather pulling hair out of your mask when you take it off after a dive! Every time = ouch.)

Snorkeling with diabetes:

  • Most of my snorkeling experiences/tips sound very similar to the scuba diving ones, so read the above if you haven’t. Remember:
    • Don’t go into a snorkel with tons of positive IOB.
    • Have easy-access glucose supplies in the outer pockets of your bag – you don’t want to have to be digging into the bottom of your beach bag to get skittles out when you’re low!
    • Sunscreen your back well 😉 but don’t over-sunscreen the adhesive on sites and sensors!
    • Make sure your pump doesn’t get too hot while you’re out snorkeling if you leave it on the beach (cover it with something).
    • You could possibly do baggies inside a waterproof bag and take your pump/cgm/phone out into the water with you. I did that two years ago when I didn’t trust leaving my pump/receiver/phone on shore, but even with a certified waterproof bag I spent more time worrying about that than I did enjoying the snorkel. Stash your pump/gear in a backpack and cover it with a towel, or stick it in the trunk/glove compartment of your car, etc.
    • Remember CGMs may not read right away, or may read falsely high, so fingerstick before correcting for any highs or otherwise dosing if needed.

Swimming with diabetes:

  • Same deal as the above described activities, but with less equipment/worries. Biggest things to think about are keeping your gear protected from splashes which seem more common poolside than oceanside…and remember to take your pump off, phone or receiver out of your pocket, etc. before getting in the water!

Wait, all of this has been about pump/CGM. What about closed looping? Can you #OpenAPS in the water?

    • If you don’t have your pump on (in the water), and you don’t have CGM data (in the water, because it can’t transmit there), you can’t loop. So for the most part, you don’t closed loop DURING these activities, but it can be incredibly helpful (especially afterward to make up for the missing basal insulin) to have once you get your pump back on.

However, if your CGM is reading falsely high because it’s waterlogged, you may want to set a high temporary target or turn your rig off during that time until it normalizes. And follow all the same precautions about baggies/waterproofing your rig, because unlike the pump, it’s not designed for even getting the lightest of splashes on it, so treat it like you treat your laptop. For my Hawaii trip, I often had my #OpenAPS rig in a baggie inside of my bag, so that when my pump was on and un-suspended and I had CGM data, it would loop – however, I kept a closer eye on my BGs in general, including how the loop was behaving, in the hour following water activities since I know CGM is questionable during this time.

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I’m really glad I didn’t let diabetes stop me from trying scuba diving, and I hope blog posts like this help you figure out how you need to plan ahead for trying new water activites. I’m thankful for technology of pumps and CGMs and tools like #OpenAPS that make it even easier for us to go climb mountains and scuba dive while living with diabetes (although not in the same day ;)).

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UPDATE in 2023: I went scuba diving recently using a Dexcom G6, and it did not have any issues once out of the water with falsely high readings! It reconnected instantly (no delay) to my phone once I was back in range and backfilled correctly and had a correct value for the most recent value. So, this is a huge improvement beyond what I described above with earlier generation (e.g., G4 and G5) sensors, but it still has the downside that it can’t transmit data underwater. You can also read here about how I use Libre for underwater reading when I’m doing several water activities and find it worth my while to invest in a single Libre sensor for having CGM data underwater.