Join Dr. Dessi Zaharieva, PhD, to answer all your questions regarding the latest AID position statement for exercise! The conversation may include discussions on special circumstances, such as exercising with diabetes, contact sports, and keeping devices on during activity.
She will be answering questions live for 1-hour on November 18, 2025 at 9AM PT / 12PM ET / 6PM CEST. The discussion is open now, so you can post your questions ahead of time if you are unable to join live.
Hello there, Harry Higgins here. Being that I’m unable to attend, below are my questions. Thank you in advance for your support thru this delicate balancing act! I appreciate you Dr. Dessi!!
As a firefighter who often goes from rest to max exertion instantly, what’s the best way to manage adrenaline-driven glucose spikes and post-call drops using pump/AID settings?
As a Type 1 marathon runner who fuels with natural carbs, how can I adjust my AID system to prevent mid-run lows and the delayed highs I tend to get after long runs or races?
What CGM and pump site locations or adhesive techniques work best for highly active people exposed to heavy sweat and heat?
How should I adjust pump or AID settings when switching between HIIT, strength training, and endurance runs, since each impacts glucose so differently?
What’s the best approach to preventing nighttime lows after intense training or fire calls—exercise targets, reduced basal, or pre-bed carb adjustments?
I’d love to have some practical settings for our son’s insulin pump for during/ after exercise.
He uses a Tandem t:slim X2 & uses “Exercise Mode”. This works fine during exercise, but after exercise can turn into a roller coaster of highs & lows.
Any advice on settings (either generally, or for the Tandem) would be very much appreciated.
Welcome everyone! I’m looking forward to chatting all things exercise and automated insulin delivery (AID) today
My name is Dessi Zaharieva and I’m an Instructor, exercise physiologist, and diabetes educator working in Pediatrics at Stanford. A lot of my research during my PhD was focused on elite athletes and adults with T1D. I’ve had T1D for almost 30 years and represented Team Canada in Taekwondo for many years. My proudest accomplishment in sport was earning a bronze medal at the World Championships in my hometown of Sofia, Bulgaria in 2013 Now, I am a purple belt in Brazilian jiu jitsu, I love to snowboard, travelling, and I love baking!
Feel free to drop your questions here over the next hour and I’m looking forward to answering them today!
Hi Harry – thank you for your service!! I have a few close friends that are FF in the East Bay, and I see how tough the job can be. Great question! Do you mind sharing what AID system and CGM you are using (no problem if not)? I realize you are not able to attend live – but I can come back here to update my reply to be more tailored to your system later on!
Personally, I think we need more evidence-based research around the management of hyperglycemia or adrenaline spikes specifically with AID systems to be honest!
First, I think it’s really important to validate and normalize that even in non-T1D individuals, adrenaline and glucose spikes are a normal part of human physiology! In fact, my PhD mentor just published a study a few days ago showing the evident adrenaline response and glucose spikes seen during a football match with professional football players without T1D!! Feel free to email me and I can send you the paper if you’d like to read it. Here is the link to the abstract: https://journals.sagepub.com/doi/10.1177/19322968251388668?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed
Overall, if glucose spikes are apparent in non-T1D individuals during competition stress, I hope this is a bit comforting to know that it’s expected and there may not be one simple strategy to prevent it. This is anecdotal, but from my personal experience, visualizations, mindfulness, and breathing exercises have helped me to manage competition stress and adrenaline spikes because I’ve replayed that scenario over many, many times in my head. But I realize this many be tricky for FF scenarios!
A few strategies to consider for the post-call drops:
Try setting a higher glucose target (exercise mode) on your pump immediately after a stressful call (or as soon as you can remember) because the pump will at least target a higher glucose value (e.g., 150 mg/dL) rather than your usual target which may be lower
Carry a glucose gel or a small 10-20 gram carb snack with you and be ready to pre-emptively treat that dropping BG when you are finished with the call
Harry, in response to your question #2:
Great question! Marathon running distances can be difficult to navigate with AID systems. Actually, another colleague recently published a study with a few case studies from Marathon runners using AID technology. I can also send you that paper, but here is the link to the abstract: https://onlinelibrary.wiley.com/doi/10.1002/dmrr.70034
A few strategies:
If you fuel with natural carbs – do you mean fruits for example and do you limit your carbs from processed foods? Do you use any electrolyte beverages like Skratch or other brands to replenish electrolytes? Some of those beverages have carbs in them and can be a good option to not only replenish electrolytes, but also prevent lows mid-run
For AID settings, I would encourage you to set a higher glucose target (exercise mode) on your pump for at least the first half of the run (you can set this 1-2 hour before a long run to give your pump enough time to bring your glucose value up)
You may try turning off the higher glucose target after the first half or in the last ÂĽ of the run because this is where some people start to notice BG spikes if exercise mode has been on for too long
Some of the marathon runners I work with like to switch the pump to manual mode before long runs because they can reduce basal insulin by 50% for example until the end of the race and they KNOW what is happening with their insulin (it can be a little tricky with an AID system when you don’t see what’s happening in the background)
I also started a separate chat on our online community forum called DiabetesWISER to reach out to Marathon runners and get some of the communities’ tips and tricks around long distance running. You may appreciate reading some of the tips people shared here: https://community.diabeteswise.org/t/calling-all-marathon-runners-with-t1d/426
From the DIY community I learned about using Temp Basal reactivity instead of “Exercise” mode. Setting a temp basal for the duration time for he activity before the activity, then turning on Sleep mode during the activity with the programed basal for that time of the day. Has there been any research in that method? It works way better for me than Exercise mode in the TSlim.
I’m a heavy sweater and do jiu jitsu haha so I can speak from experience on this one!
I always encourage using the CGM manufacturer approved sites because those have been specifically tested. For example – Dexcom G6 sensors may be inserted on the abdomen (indicated for patients age 2 years and older) or the upper buttocks (ages 2-17 years) and Dexcom G7 sensors may be inserted on the back of the upper arm (ages 18 years and older). These sites have been studies and are the most optimal for accuracy and performance. Each sensor company has their own approved sites – so check that out first. Similar story for pump sites!
For heavy sweating, you may consider a rash guard underneath your FF gear for example because this is something I wear during jiu jitsu and it’s snug over the skin and keeps my CGM in place (and it’s less likely to get ripped out).
This is definitely a strategy that some people use although there is no specific evidence-based exercise study testing this strategy (that I’m aware of). A lot of the AID and exercise literature is evidence grade E unfortunately, and this means that it is based on expert-level consensus in a lot of the published guidelines. We simply need more studies out there to test out the different scenarios around exercise. Although there are so many!!
For the sleep mode during exercise - this is one strategy I have seen, but I will add a little caution with using sleep mode in cases where glucose spikes during activity because the pump does not deliver automated boluses during this time when sleep mode is on.
Set a higher glucose target 1-2 hours before the exercise until the end of activity
Consider reducing mealtime bolus insulin by 25-33% with the meal before exercise if the activity will occur within 2 hours of the meal
If glucose drops below 126 mg/dL, consume small carb snack (3-20 grams)
If glucose levels spike with activity:
Depending on the AID system, you can consider setting a lower glucose target at the start of exercise or maintain the system in automated mode (with no exercise mode set)
Administer regular mealtime bolus insulin with the meal before exercise
Less carbs typically needed since hypoglycemia is less of a concern
Totally! Remember that exercise can increase insulin sensitivity for 24-48 hours after exercise – especially if you’ve had a busy day of calls or even a long call!
A few tips:
Set a higher glucose target at bedtime on your AID system and keep this on for 6 hours or overnight
Consider a small, uncovered (no bolus or reduced bolus) snack with some protein and fat to help maintain BG overnight (e.g., cheese and crackers, yogurt)
Check your insulin on board (IOB) on your pump at bedtime and consider a larger snack before bed if you have elevated IOB before bed (e.g., with 25-33% reduced bolus insulin)
Hope this helps!!! Please reach out if you have additional questions
Hi Dessi! Control IQ on the t:slim pump and Dexcom g7 has changed my life in the last few years. My only complaint, usually, is that I can sometimes go on a roller coaster of treating a low from exercise to correcting a rebound high after. Going into exercise mode on the pump helps, but I occasionally still have those days where a Pilates class throws me into an endless loop of low to high back to low. Are there other tips for AID users to avoid the algorithm from treating a rebound high too aggressively, or should I focus on trying to have fewer carbs to treat the low? Thanks!
Great question @TamaE! I’m happy to hear it’s working during exercise. And totally understand the struggles post-exercise.
A few strategies:
If your son seems to have more patterns or consistent highs post-exercise, consider turning Exercise mode off before the end of exercise as it may be trending high depending on the type and intensity of exercise (sometimes it may not be needed for the full exercise, especially if it’s a long activity!)
If your son notices more consistent lows post-exercise or glucose levels trending down, make sure to get some fast-acting carbs in asap (if glucose is 126 mg/dL and dropping post-exercise). It’s best to pre-emptively treat a low before it happens if you can!
Another little “trick” with the Control-IQ system is to give the smallest possible bolus dose before exercise starts (example: 0.05u) and this will disable auto-corrections for the next 60 minutes and may help reduce the risk of lows during exercise
It’s also important post-exercise to refuel the muscles and the depleted glycogen stores so plan to have a balanced meal soon after finishing exercise
Remember, you can delay the meal post-exercise a little bit if glucose levels are high, or you can start eating the lower carb parts of the meal first like salad or veggies first and save the carbs to the end
Consider talking to your diabetes care team to set up 2 different Personal Profiles – 1 can help with post-exercise highs and 1 can help with post-exercise lows. This can be tricky because you may not know what the activity will do to his glucose levels, but if you see trends in glucose responses, this may be a helpful option
For instances where glucose levels decrease after activity, a Personal Profile can be created that can reduce insulin delivery (e.g. lower basal insulin doses; higher insulin sensitivity factor; lower insulin-to-carbohydrate ratio
Can you use the Temp Basal to be used as a different profile for activity instead of creating a new profile and switching to that and back to the normal profile?
I use a Tandem t:slim and Dexcom G7. I know that everyone is different in their exercise needs. I have my routine for exercising in the morning finally figured out and it works great (turning off insulin approx 60 minutes prior to exercise in the morning. Starting exercise once my BG hits about 125 and then turning my Sleep Mode back on - no roller coaster levels after workout. Its amazing!).
My issue is how to best deal with spontaneity and suddenly going for a walk after dinner (with I.O.B.) or hiking with friends, et cetera. I’m very sensitive to any I.O.B. and don’t want to eat half the refrigerator just to go on an unplanned walk. Other than using glucose and turning off insulin, are there any practical tips for unplanned exercise (walking) that you’ve come across?
Ah, the unwanted roller coaster ride - such a common occurrence for us T1D folks hahah. I’m glad to hear all of the positives with Control-IQ
A few tricks that may help with the rebound highs and lows (maybe some you’re already doing):
Since AID technology has an algorithm working in the background, if your glucose levels are dropping, the system is already ahead of you and pulling back on insulin so it’s always important (and vice versa when spiking, it is already ramping up insulin). So to help with the lows in the rollercoaster, I always encourage really small carb feeding in advance of a low - so if you notice after pilates you are <126 mg/dL and dropping, a small 6-9g fast-acting carb can be really helpful! This is different from what we have been taught in the past (15 g wait 15 minutes - try smaller carb feeding and earlier)
For the highs, this on is a bit tricky because if you go above target, the AID system will automatically delivery more insulin and this is what usually leads to the up and down. Similar to what I mentioned to Tama, one tip is to use your exercise mode and try delivering the smallest possible bolus dose (0.05u) just before pilates, and this tiny bolus will stop auto-corrections for the next 60 minutes so it may make it easier on the system (and on you!)
Last tip, although not always optimal, is to consider switching to manual mode before pilates and setting a reduced temporary basal rate (50-80% reduction) at least 1-2 hours before pilates until the end
@Sjwoodward For Control IQ, Personal profiles are still used in automated mode and you can adjust settings like lower basal insulin doses; higher insulin sensitivity factor; lower insulin-to-carbohydrate ratio for example. But you would still be using this setting as automated mode, not manual mode. If you want a very specific basal rate reduction like 50% and no automation, it’s best to be in manual mode. For DIY Loop, the system settings can be changed with different overrides, but the system still works in automated mode. Similarly, if you turn the Loop feature off, you are going back to manual mode.
What was the most exciting thing to come out of the position statement? What were you most excited to share with people? And maybe, what are you looking forward to with the next position statement (what’s up and coming)?
What’s the best way to overlay wearable data (between CGM and activity tracker)? Or, what do you recommend to look more comprehensively at impact of exercise beyond just the time point of activity (things like glucose, HR, stress, etc.).
