Usability Considerations

Now that you’ve closed the loop, you probably have a lot of new “first” experiences to deal with. Like much of this looping experience, you’ll figure it out as you go along, and figure out what’s right for you. But here are some ideas or tips to consider:

What do you do with the loop in airport security when you travel


The loop is off the shelf hardware - it’s no different than your phone or other small gadgets, so leave it in your carry-on bag when going through security. (Dana note: I have traveled well over 100 times with my loop, and in some cases with 3-4 Pis and batteries and related accessories, and have never had issues going through security because of my loop.)

What do you do with your loop when you travel across timezones?


You have a couple of options. If you are traveling briefly, or only across a couple of timezones, and would not normally feel the need to adjust the timing of your basals, then you may choose to simply leave your pump, receiver, and Pi/Edison on your home timezone. But, if you would like to adjust to the new timezone (perhaps for a longer trip or a move), you can adjust your rig’s timezone using sudo dpkg-reconfigure tzdata and then either run killall -g openaps; oref0-set-device-clocks to set the devices to match, or just change your pump and receiver time manually. Make sure to test in your new location to make sure everything is working! We also recommend planning to do this when you have some extra time for troubleshooting, in case you have issues. Also, it’s worth noting that your body only changes about an hour or so of timezone a day, so even if you go abroad, there’s not a rush to change timezones/the time on your devices - you can wait until 2-3 days into your trip to make the swap, at a time when you have some room to update your rigs.

What do you do with the loop when you shower?


Because the pumps aren’t really waterproof, most of us choose to suspend and disconnect our pumps before we shower. You’ll do the same thing even after you’re looping. One trick, though, is to cancel any running temp basal rate and set a temp basal for 30 minutes with a rate of 0.0, and then suspend the pump. This will help OpenAPS accurately track your netIOB while you are off your pump. When you get out of the shower and are ready to reconnect your pump, do so. Make sure to unsuspend it. You can then either manually cancel the zero temp basal; or let OpenAPS read and decide what temp basal to issue next.

What do you do when you exercise?


This varies from person to person, and depends on the type and length of activity. Here’s a few tidbits from Dana on how she does various activities. (Other loopers, PR into this page with your additional tips and how-to’s.)

  • Hiking - Definitely take the loop with! Think about setting a temporary target (you can enter it in Nightscout if you have connectivity) higher for the duration of the exercise. If you’re offline, just change your targets in your pump. The loop will read the adjusted targets and begin looping toward that target. When you’re done with the activity, change your targets back. In this scenario, I might change my loop target from 100 (normal day or nighttime) to 130 or 140 as a target.
  • Swimming, Snorkeling, Scuba Diving, etc. (water sports) - You can’t loop while you’re in the water, because the pump is not waterproof. (Unless you’re sitting in a hot tub and have your pump safely above water, along with your CGM sensor being above water so it can transmit to the receiver, which is also not waterproof.) You can try having your sensor on your arm and keeping it above water so it can read every now and then if the receiver is in range. That being said, again, pump is NOT waterproof so you’ll need to apply shower methodology (temp to zero, suspend, take pump off) to best track your netIOB. Some people observe having the CGM, once it gets back into range and reads data after the sensor has been submerged, read falsely high. It’s not a big deal for the loop (because it’s looking at trends, and doses using temp basals in a conservative way), but you’ll likely want to fingerstick and/or wait a while before you’ll be really happy with your CGM results again. See below for another strategy that could work as well if you’re much more active than usual.
  • Running - If it is a short run, (<30 minutes), I may not take the loop with me because any adjustments it would make are going to impact me after the run is done. For longer runs, I often now take my small, Edison based rig which can slip into the pocket of my hand-held running drink bottle that holds Gatorade. Before any length run, I try to make sure I don’t have much positive netIOB on board (that’s the biggest key to success). I also turn on activity mode (essentially a temp target of 120-140 or changing my pump targets to 120-140) an hour or so before a run and during the run; especially if I am carrying the loop during the run.

For any exercise or activity or time period, if you do not choose to take your loop (or if you forget it), the loop will pick up again once you get back into range and resume. (This is why it’s important to temp then suspend so it can track the amount of insulin you haven’t been getting.)

What do you do if you want to be off the pump for long periods during a day when you’re really active? Like for the beach or water park or sporting activity or similar?

Let’s face it. There are some days when you just don’t want to be attached to a pump. It’s not uncommon for kids at diabetes camp to take a “pump holiday” where they revert to insulin injections in order to be unencumbered by the pump as they run and play and swim. Unfortunately this means a trade off - giving up the safety of closed loop control. Some have employed a strategy to be off the pump while active for extended periods but still have the advantages of closed loop assistance during less active periods of the day and overnight by using a combination of long acting basal injections in conjunction with the closed loop, in a manner similar to the following. Note that this will only work on days that you’re really, really active (and as such will have significant reductions in your overall basal requirements).

  • First - Look at your pump and determine your 24 hour basal insulin dose.
  • Second - Create an alternate basal profile (Profile A or B) on your pump with settings for each time period that are half of your normal settings (we’ll call this a “Half Basal” profile). You’ll also want to make a “Half Basal” profile in Nightscout with the new settings, and consider establishing target glucose ranges for the entire 24 hour period that are higher than you might normally use (use values similar to what you would use for activity). For children a reasonable choice might be 140-180 but yours may be different.
  • Third - On the morning of the active day, record the time and give an injection of long acting basal insulin at HALF THE USUAL DOSE of your usual 24-hour basal requirement (which you determined above). At the same time switch your pump to the “Half Basal” profile you created. You’ll get half the usual basal dose from the injection, and half from your pump. You should also change your blood sugar targets on your pump to whatever you decided on when you set up your alternate profile above (don’t forget to change them back later). Use the + icon on Nightscout (upper right corner) and choose event Profile Switch to Half Basal (or whatever you called it) in order to assure appropriate visualization of the basal settings via Nightscout when you have connectivity.
  • Fourth - During periods when you’re going to be very active, disconnect your pump and set an extended temp basal manually of 0.0 (choose a duration of several hours, or as long as you think you might be off the pump), and then suspend. This will allow the APS to track the negative IOB. Obviously since you’re going to be off the pump (and if in the water, potentially without the benefit of CGM data as well) you’ll want to remember to test more frequently.
  • Fifth - Hook back up to the pump for meals to bolus and/or correct for hyperglycemia, and for periods where you’ll be less active during the day. Don’t forget to reset a temp basal of 0.0 when you suspend again in order to track negative IOB
  • Sixth - At the end of the day, hook up to the pump, cancel your temp basal of 0.0 and start looping again. If you’ve been in the water, recognize it may take some time before your CGM data regains full accuracy, so you may still want to check more frequently. Check and make sure your pump is setting temp targets appropriately and check Nightscout to make sure all is going as you expect. You should still be on the “Half Basal” profile.
  • Overnight - The loop will titrate your basal up or down in response to your CGM data. The caveat is, of course, that even if it lowers your temporary basal to 0.0 you will still be subject to the effects of the dose of long acting subcutaneous insulin you took in the morning. This will render the loop somewhat less effective at avoiding hypoglycemic events, and is in part the reason that higher than usual targets for blood glucose would be appropriate. Recognize also that after intense periods of physicial activity it is likely you will be more insulin sensitive, which could exacerbate the potential for hypoglycemia. Better to be safe and run slightly higher than normal.
  • The Next Morning - Around 24 hours after the time you took your long acting insulin dose, switch your pump back to the normal profile, and readjust your glucose targets to your normal values on your pump. Use Profile Switch in Nightscout to switch back to your usual profile. Continue to monitor yourself somewhat more frequently until you’re sure things are completely back to normal and all of the effects of the long acting insulin bolus from the prior day have resolved. Alternatively, if you’re going to have several days of similar activities in a row, you could take another long acting basal dose and go at it again. Use your experience from the prior day to adjust that dose up or down slightly depending on how things went with your first day’s glucose readings.

What if I want to turn off the loop for a while?


One easy way to “turn off” the loop for a period of time so to use temp targets in your Nightscout website. You can set an wide range from -1000 to 1000 as a temp target for a period of time and it will effectively turn off the loop. What is great about this is that it is easy to do and allows you to schedule the time when you want the loop turned off (going swimming, showering, exercising, etc). You do not have to power down your device or mess with cron commands. You can also choose to leave it at home if you are going out and do not want to be looping during that time. It will start looping again when you get back into range and it can successfully read your pump and CGM data again.