I love this thread and seeing so many diathletics! Go go go!
YES! I am less than happy with the Medtronic closed loop, and I am looking into the Omnipod system as my next step. A lot of type one diabetic cyclists feel like it out performs the medtronic system. Regardless I have really enjoyed having the closed loop.
I will have to transition to the xDrip/nightscout. The lack of notifications and alarms with lows is a serious issue for me as well.
Thanks for the responses! Really appreciate them. I think I have been under-sugaring myself (I know that sounds silly) and have been trying to keep my sugars down, even on hard rides, so that I end up not having enough energy and feeling flat. I’m going to try to fuel myself closer to what I used to do, let my sugars climb a bit more than I have, and then see what happens: hopefully they will drop after I end my ride, and my ride will be more productive. I really appreciate the feedback—Jonathan
Thanks @jonathansimmons for the bump, I hadn’t seen the thread. It sounds like you’ve got a good handle on it already. The levels you achieve 1 hour post ride are what I try to aim for.
I’m a long term cyclist and T1D, so some differences to T2D but also some commonality, so thought I would share some of my experiences in case they are useful.
Tech-wise I use Dexcom G6 CGM, xDrip/Nightscout and display my blood glucose levels on my Garmin. As others have said it’s a great set up. I don’t use a pump, but inject instead (slow acting/basal - Levemir, fast acting/bolus - Novorapid),
I find on nearly all rides my levels will drop over the course of the ride and level out to between 4.5 and 6.5 mmol/L (81 and 117 in mg/dL), a very similar range to @SirNorden’s top graphic. I very rarely see an increase in levels whilst cycling even when effort levels are higher, although I have a lower level of top end efforts in my riding plan.
I nearly always spike 15 ~30 minutes after a session. My assumption is that this down to the increased cortisol levels and residual food still being digested. Insulin sensitivity is also higher during exercise, so once exercise stops sensitivity will fall back again. I think glucose can be absorbed from the blood stream more readily without insulin during exercise, but this is really where one of @chad’s deep dives on nutrient timing and hormone interaction come into play (I think there are some which cover these areas already).
If I am on the turbo at home I will inject 15~30 mins before the end of the session to compensate for the spike above and also to cover my recovery drink (40g carbs/10g protein). N.B. I only do this at home so I know I have food to hand if needed.
I have found that any residual bolus insulin will dramatically increase the risk of a hypo on the bike, so I do not take any bolus insulin before rides, and prefer to have at least 2 hours gap starting after when I think my bolus insulin will have finished acting (so maybe 4~5 hours in total since last bolus depending upon dose).
I tend to keep my basal insulin unchanged (two injections 12 hours apart), however as my fitness increases I find I may adjust the morning dose down to maintain steady background levels.
For context my diet off the bike is relatively low carb (no rice, no pasta, no potatoes, no cereals, but lots of veg and meat) to minimise the need for higher bolus doses and reduce the chances of a roller coaster ride with levels.
Before and during workouts I will eat carbs, probably 50g (oats, honey) before the ride, only 25~50g per hour during the ride (but looking to increase). This level seems to be covered without taking insulin as above.
Obviously usual caveats apply, i.e. what works for me might not work for anybody else and things are always slightly different day to day
All part of the fun!
Always happy to help @jonathansimmons actually i think the idea about looking abit into the on bike nutrition could help, as having a steady supply of carbs might actually lower the stress response abit so your body can preserve its energy stores for longer, so you can ride more before feeling flat. As long the glucose levels dont get too high so it impairs performance and still do come down to a good level afterwards it should all be good, as my endo says: going slightly too high (compared to normal levels) while riding is not the end of the world if everything is good the rest of the time, the total time in range is what matters.
@ktmccusk I heard that aswell about the Omnipod, and i must admit i kinda like thinking about beeing able to remote bolus/basal from my phone during a, in stead of having to “dig out” the pump from a pair of very tight bib shorts The transition tto xDrip/Nightscout might feel like abit of work to begin with, or well… the xDrip part is quite easy however Nightscout can seem abit harder but i found their guides easy to follow and when its setup properly… it just WORKS, and no missed alarms or notifications, in fact…idk if its just me but i find it almost impossible to miss an alarm i can hear my phone alarming me from almost 100m away but that beeing said, if you were to transition into a Dexcom w/ Omnipod system you will stil have the option to have a closed loop, its gonna be a DIY solution tho through OpenAPS or AndroidAPS, but from the “loopers” i talked to who already has a DIY loop setup i only heard good things and it should work out just perfect!
And then ofc thank you to @MBW for sharing your experience, makes me happy to see i aint the only one dealing with the problem of residual bolus insulin on the bike, i need an approximately 2 hour “clear time” just like you do before a ride, also when having it with a meal. I need the bolus to have totally cleared my system overwise i go hypo.
For that very same reason i dont really eat anything during my rides, i found that as long as a workout requires less than 1800 kJ of work i can get away with not fueling and just run on my body’s glucogen stores, however… i must admit, when approaching the 1800kJ range i can feel the stores run low immediatly. The reason i dont eat during those less than 1800kJ rides is because of the temporary basal dosing i use, i found that perfect sweetspot were i can ride were the numbers are just more or less stable… i also think that might be the reason why the stress from those harder VO2 and anaerobic workouts cause my blood glucose to increase. I have however thought about changing that approach abit since bolusing during a ride is a total no go, i am VERY insulin sensitive, i only use about 30 IU total a day (basal + boluses) and thats on a diet with 650-800 grams of carbs daily (except for the one weekly rest day), in fact the lowest possible dose my pump can apply is 0.1 IU and thats enough to bring me from 13mmol/L (234 mg/dL) and down to beeing hypo. However i must admit i have thought about lately changing it to a setup to get the pump to mimic the way your Levemir does, by changing my basal dose slightly up so i will have to eat abit of carbs to keep the same stability, i was unsure about how many carbs would be needed but i will give your layout a try. I have been able to get away without the carbs so far since the mens elite mtb xco races are juuuuust short enough to keep me under the bonk limit however xcm racing has been a total mess for me, either i bonked or ended getting way too high which is just as bad for performance, so def gonna try that strategy out with mimic’ing the levemir and then try your hourly carb dosing, so thank you for sharing that