Redefining diabetes for athletes

Managing blood glucose levels while participating in athletic endeavors can be difficult. After speaking with a few athletes living with diabetes, we have learned that one of the most impactful resources is often what we learn from within the community. Your diabetes may vary, and management will look different for every person depending on the activity of choice, lifestyle, etc. but our friend Courtney Duckworth was kind enough to share her experience as a runner with diabetes and how she trained for the Boston Marathon while completing her fourth year in medical school.

Q: What is your diabetes diagnosis story?

I was diagnosed with diabetes when I was 10 years old. One of my first questions after diagnosis was whether or not I would be able to continue skating, because if I could do that, I knew I would be ok. With a learning curve that involved more strategizing than before, I was able to skate, dance, and run, training for events on some of the world’s biggest stages (like running in the Boston Marathon or dancing in the Stanley Cup Final!). .

Q: What was training for the marathon like? How did diabetes factor into your sessions?

For my first marathon, I didn’t have an insulin pump or a continuous glucose monitor (CGM) so I had to test my blood sugar along the way. I had to play with the amount of insulin I took (both long and short acting). This strategy shifted drastically when I started using an insulin pump, and then shifted again when I transitioned to using a closed loop system with an insulin pump and a CGM.

Every run is a science experiment. I try to one change one variable at a time, which means that I wake up at the same time and eat the exact same thing at a fixed time before I run. I have created a calculated insulin profile for myself so I can use that during runs to allow me to eat carbs and stay in range.

Q: How have you identified a safe target range for your runs?

All of my training runs take place in the morning, because that’s when the marathons take place too! Exercise in the morning is safer because you have less insulin on board. Starting a run with a blood sugar of 110 mg/dL in the morning compared to starting a run of 110 in the afternoon is a completely different story. I always wear my medical ID and carry fast acting glucose, because you just never know. When I do run in the afternoon, I run closer to home and eat more carbs, but I have seen that I am far less consistent at that time of day.

Q: How do you handle extreme blood sugars while running?

With my CGM, I can see the lows coming so I know to eat more carbs (usually a GU Gel).. I have sometimes gone into the 70’s and mid 60’s which is uncomfortable but you do have to see what your body can handle. My threshold for staying in the race depends on what my CGM is doing - there is a big difference between a slight arrow down vs. double down arrows. For high blood sugars, if it is not coming down and something seems fishy, I will maybe change my site out depending on how elevated my glucose is and how long it has been that way. When in doubt, change it out!

Q: How did the Boston Marathon itself go?

It went really well considering that I had just finished a year of clinical training in medical school. Third year was difficult because sometimes I was waking up at 5am and coming home at 9pm, trying on every medical specialty. I molded my marathon training schedule around my clinical schedule, so given that context, it went very well! The crowds and people cheering you on in good weather was really nice compared to the rain we had last time. I gave myself the grace to aim to finish under 4 hours, and I finished in 3:38.

The NYC Marathon was less than a month later on November 7th, 2021, and I finished in 3:29—good enough for a Boston Marathon qualifying time!

Q: Generally, how does your diabetes data inform your approach to exercise?

Especially with endurance events, I take in more carbs than I normally would. I increase the carb load in my diet weeks before the event, which makes training extremely tricky because I normally eat pretty low carb. Having the data to see postprandial BG levels is extremely important. Staying in range is important for recovery as well. Taking in more carbs while also decreasing activity while tapering before a race is difficult, and the data helps make that a little easier.

I mostly focus on my Time in Range. My personal goal is around 80%, but the range prescribed by your physician could be different. Trends are so important, where am I going high? While I am training for an event, I actually use old fashioned paper and pen and include my blood sugars in my training log. How did last week’s run go? What should I change this week? I capture how much insulin I took, what I ate, my workout, and even what clothes I wore (down to my socks)! Details matter.

Q: What improvements would you like to see in diabetes software to better support marathon runners, triathlon participants, and other endurance sports athletes?

I wish there was something to help people realize how big of a difference diet makes. People assume that as an active person with diabetes, you have better glucose control. But according to recent work from Sheri Colberg, your diet is much more important than activity levels. It would be so useful for people to have a tool that explains the quantity and quality of carbs in relation to glucose outcomes.

Courtney also finished the New York Marathon with the Beyond Type 1 team in November, and wrote a book about how she uses her marathon training to help live her best life with diabetes.

We invite you to join us along the pathway we’re building to make an interoperable automated insulin dosing system a reality and drive change across the entire diabetes community.

We can Redefine Diabetes together when you support Tidepool with a donation at tidepool.org/donate.