Staying active is a staple of health with type 1 diabetes (T1D). Whether you’re new to exercise or a seasoned athlete setting goals, many people who live with T1D share in your experience. If you haven’t dialed in how to do it best — you’re in the right place. 

To find out more, T1D Exchange sat down with exercise expert Dessi Zaharieva, PhD, CEP, and CDCES, an accomplished athlete and instructor in Pediatric Endocrinology at Stanford University School of Medicine, who has lived with T1D for over 28 years. 

Zaharieva is a translational researcher who simplifies scientific findings around exercise and diabetes management to help guide day-to-day decision-making. In other words, she has a wealth of evidence-based knowledge on exercising with T1D. 

What’s more, she understands the challenges of T1D in sport, as a second-degree black belt in Taekwondo who competed for Team Canada and medaled at the World Championships — and now as a purple belt in Brazilian Jiu Jitsu. 

In this article, we’ll explore what science says about exercise with T1D and offer practical, researched steps to explore with automated insulin delivery (AID) devices. 

 

Diabetes + Exercise  

If you’re already active, you’re familiar with the many variables affecting “how well” an exercise session goes — and know that figuring out what works best takes time, consistency, and dedication. 

Lucky for us, Zaharieva is behind the scenes, conducting complex investigational research to help people living with T1D overcome common challenges and roadblocks.  

When it comes to rallying for exercise, people with T1D have considerations beyond personal motivation and physical fitness. That’s why it’s normal to have a mental rundown that probably sounds something like this: 

 

 

Simply put, there’s a lot of mental baggage carried around with T1D. That’s why, when I think about a life without T1D, I wonder what it would feel like to simply exercise. Just lace up my shoes, consider the weather, and hit the road. A girl can dream, right? 

In the meantime, why are there so many questions? I asked Zaharieva, “Are we overly concerned, or is this normal self-talk?” 

“These are things I think about every day of my life,” said Zaharieva. “What’s important is that even as someone who has dedicated my life towards this, it was through my experience that I would often think: ‘I can’t be the only one struggling to navigate T1D and exercise — there have got to be other people.’”  

“It’s also why we’ve done things like build out resources for technology, exercise, and device use and have it widely accessible through DiabetesWise and an online community forum called DiabetesWISER where anyone can ask questions or chat about diabetes technology and exercise.”  

“We’re trying to have everything we’ve learned about incorporating T1D management strategies with exercise as available as possible,” said Zaharieva, who shared that many of her colleagues at Stanford also live with T1D, so resources are designed for people with type 1 from many who live with type 1 as well. 

Zaharieva explained the importance of knowing what devices are integrated and how they can help with exercise. The DiabetesWise device finder webpage was built specifically with that in mind.  

Further, each insulin delivery system is different, so understanding your pump’s capabilities is critical. The DiabetesWise Pumps for Exercise webpage also breaks down this information system by system and offers tips and tricks to navigating exercise and T1D. 

 

Exercising with an automated insulin delivery (AID) device 

Exercise causes glucose fluctuations that are sometimes hard to predict. Which leads to the beef of the matter: How can diabetes technology improve our relationship with exercise? 

According to Zaharieva, it’s by knowing what researched “best steps” are, trying them on for size, and tailoring them to fit your needs.  

To help define this, Moser & Zaharieva and their colleagues recently published: “The Use of Automated Insulin Delivery Around Physical Activity and Exercise in Type 1 Diabetes: A Position Statement of the European Association for the Study of Diabetes (EASD) and the International Society for Pediatric and Adolescent Diabetes (ISPAD).”  

 

 

 

Although these guidelines are a great place to start for anyone with T1D — keep in mind the many types of physical activities (some of which raise glucose levels), and that scenarios vary day-to-day and person-to-person — even within the same person, reminded Zaharieva. 

For these reasons and others, it’s important to be realistic about results. After following the steps above, you’ll likely discover what changes work best for you — or dial them in further with the help of your diabetes care team.  

 

FAQs about T1D and Exercise 

T1D Exchange asked Zaharieva to field some frequently asked questions about exercise with T1D. Here’s her practical advice and evidence-based answers for optimal benefits. 

 

What are the best practices for CGM use? 

“CGM systems are typically tested at rest, so they work best at rest,” explained Zaharieva. “It makes sense that movement can affect accuracy or lag time in a device tested and approved on people at rest.”  

“That’s why you may notice a CGM lag time of around 15-30 minutes during exercise.” It’s also why it’s not suggested to calibrate during exercise. Instead, wait until you’re 30 minutes into your recovery window to allow things to settle down. 

“Rapid changes in glucose are hard for a CGM to keep up with.” As a result, delays and errors are expected with rapid glucose changes. 

“It’s where you see the most fluid shifts and things happening in your body, so when you’re exercising, and glucose starts to drop quickly, the interstitial fluid (CGMs read) is trying to catch up and mimic what’s happening in the blood.” 

  

How do I avoid glucose rollercoasters? 

“You can avoid some of these swings by being proactive and treating lows before they happen. CGM trending is great at helping with this ahead of time.” 

“Once you’re low, we know it’s common to overtreat because you just don’t feel great. If you’re treating a glucose of 60 or 70 mg/dl with double arrows down, your finger stick may be even lower during exercise, and you’ll be more likely to have too many carbs.” 

“If you can have a small amount of carbs when your glucose is 126 mg/dl and dropping (before you’re low), then you’re less likely to overeat. So, our encouragement is to have more frequent and smaller amounts of carbs during exercise (more on this below). This can also help to avoid an auto shut-off or follow-up auto bolus that happens with a rapid rise in glucose.” 

“We’re normalizing treating lows before they happen and also knowing, if you go low, you can sometimes expect to spike depending on the carbs you ate and the system you’re using,” said Zaharieva. “Once the ‘yoyo’ or ‘rollercoaster’ starts, we want to normalize that this may happen, and it’s a challenge that these AID systems weren’t built with exercise in mind.”  

 

What does changing a glucose target do? 

“If someone changes their glucose target, that can automatically adjust other settings too. In other words, if you simply do one thing, it can amend a handful of other things.” 

That’s why Zaharieva says, “If there’s one tactic to try without eating a bunch of carbs or adjusting multiple settings, we still encourage setting a higher glucose target 1-2 hours before exercise to reduce the risk of lows.” 

“It takes time to get your glucose value upwards of 150 mg/dl, especially if your usual target is 100 mg/dl,” explained Zaharieva. “If you could do one thing and build a habit around it, it would be setting a higher glucose target throughout exercise.”  

“I do this regularly and have alarms set on my phone for 1-2 hours before I train. This will reduce the amount of IOB, and starting with a bit of higher glucose helps to prevent lows and may stop glucose corrections, depending on your system.” 

 

What role does fear of hypoglycemia (FOH) have in exercise? 

“It could be significant,” said Zaharieva. “Fear of hypoglycemia is one of the leading barriers to exercise in kids and adults with type 1 diabetes. It’s been shown since 2008, and rarely has that shifted — it’s still one of the leading barriers.” 

“I honestly don’t love the phrasing of having a ‘fear’ of hypoglycemia. I do understand that some people are quite fearful of it, while others may have ‘worries’ surrounding hypoglycemia.” 

“But I think it’s important to point out that hypoglycemia is a barrier in and of itself, because you have to think through a long list of things to combat it during exercise.” 

“It’s a mental barrier that has to be worked through,” said Zaharieva. “FOH can be a burden and a block to exercising. I try not to think about it as a ‘fear’ per se, but as a ‘barrier, worry, concern, or challenge’ that we often have to navigate.” 

 

How do we overcome common hurdles with exercise? 

“Try to be patient with it and take it one day at a time,” said Zaharieva. “If you didn’t have a great day today with something you tried, try again tomorrow.”  

”My hope is that people don’t want to give up on sport. It’s not going to be perfect — we’re not even aiming for perfect — we’re just trying to get through the activity and have fun.” 

Most importantly, don’t change too many things at once. “If you’re just trying to be active, and you change seven things at once and things don’t work, how do you know which one it was?” 

Instead, implement small changes and wait a few days before trying something new again. Then, think through those factors after exercising. 

“Reflecting is important. If you just say, ‘It failed,’ and don’t take a moment to reflect, it’ll be more challenging to know what to change next. I teach a lot of trial and error, meaning you try something and think back on it. And did it work or not?” 

“Make small changes, remember every day is new, and try not to strive for perfection. Showing up and being active is the most important part,” said Zaharieva. 

 

How do I eat for sport and not just for my glucose levels? 

“This is one of the biggest challenges for me as an educator. There’s a disconnect because we have to fuel for performance aside from diabetes, but we also have to fuel to treat and prevent lows — and they’re two very different things.” 

“For an average athlete, we typically recommend .5-1g of carb fueling per kilo of body weight per hour for performance reasons,” said Zaharieva. “So if you take a 60-kilo person, that’s 30 to 60 grams per hour, which is very different (much more carb) than if you were trying to prevent a low.” 

“One is nutrition fueling guidelines, and the other is that we can’t have 60 grams of fast-acting carbs to prevent lows — that would just be crazy. So it’s two very different things.” The question is: How do we balance that? It’s most likely by spreading smaller amounts of carbs throughout the hour.  

“Thirty carbs is pretty doable. You could have a 15-gram gel at the top of the hour and another at the end — and get your 30 grams per hour.” 

“Generally, you’ll need a different composition of carbs for fueling than to prevent lows. Some of that might have to do with what a person uses to fuel,” said Zaharieva. “While gels help prevent or treat lows because they’re fast glucose, having a full-meal composition before an activity with more carbs, protein, and some fat will provide ongoing energy and protect on the front end of the activity.” 

 

Are we more likely to need electrolyte replacements with T1D?  

“Although research in the area is limited, people sometimes find artificial highs and lows in their CGM readings with dehydration, which are basically inaccurate values related to volume and concentration of fluids in the interstitial space.” 

“While there isn’t much guidance on electrolytes in T1D, I always encourage people who are active for long periods or doing intense exercise events to supplement with electrolytes.”   

“Just like everyone, it’s important to replenish the stores you lose through sweat — and to look at the options. They don’t necessarily need to have a ton of sugar in them. You can look at the labels and choose what has little or no carbs.”   

“If you want an electrolyte supplement with carbs and you’re sipping at it during exercise, that’s generally OK,” said Zaharieva. “It’s just important to look at nutrition labels because the carbs vary so much from one brand to the next.” 

 

How do we keep devices attached during and after exercise? 

“I understand first-hand that wearing diabetes devices during exercise can be challenging.” 

“I commonly hear, ‘I can’t wear a device during exercise because they fall off all of the time,” said Zaharieva. “I’ve found things that work well for me and others, which is why sharing this information is important, so it isn’t a barrier or an ongoing issue for people.” 

Trying different overlay tapes, adhesives, or glues, as well as other use tips, can be a game-changer.