Managing diabetes as an athlete or physically active individual can feel like running two races simultaneously. Aside from meeting demanding training schedules, athletes with type 1 diabetes (T1D) must develop a strategic approach to managing blood glucose levels. Unlike routine athlete care, these individuals face unique challenges, from unpredictable glucose swings to elevated dehydration.
What is Type 1 Diabetes (T1D)?
Here is a quick refresher on the difference between type 1 and type 2 diabetes:
- Type 1 diabetes is an autoimmune condition in which the body’s immune system destroys the cells in the pancreas that produce insulin.
- Type 2 diabetes: The pancreas makes less insulin than it used to, and the body becomes resistant to insulin.
Both types pose challenges; this blog focuses on T1D because of its prevalence among younger individuals and its unique implications for youth athletes.
To best support an athlete with T1D, one must understand how the condition impacts the body, recognize the effects exercise and nutrition have on glucose levels, and embrace the importance of a team-based approach.
Benefits and Barriers of Exercise in T1D Management
Research shows that there are many health benefits to physical activity, sports, and exercise for people living with T1D:
- reduction in long-term cardiovascular disease risk
- reduced insulin resistance
- improved blood pressure and endothelial function
- reduced risk of diabetic retinopathy
- Reduction of glycated hemoglobin (HbA1c)
- improved fitness and sense of well-being
Managing T1D and exercise presents unique challenges. In addition to the barriers reported by the general population, surveys of those with T1D highlight several additional limitations:
- fear of hypoglycemia
- worrying about poor performance or under-performance when blood glucose readings are high (low is also a concern)
- lack of confidence in managing diabetes around sport/exercise
- difficulty in engaging in spontaneous exercise due to a need for planning around diabetes
Athletes with T1D can experience these concerns more severely or more frequently. These include younger athletes still growing or going through puberty, athletes trying to maintain weight for ‘weight category sports’ or endurance sports like marathon running, or athletes building muscle bulk/strength for power-based sports.
How Physical Activity Impacts Blood Sugar in T1D
Physical activity creates a delicate balancing act for athletes with T1D. Their bodies can’t naturally adjust insulin levels because they do not produce insulin and must use prescription insulin injections. Therefore, close monitoring and careful planning are non-negotiable for these athletes, their parents, and support staff. Given the complexities introduced by physical activity in glycemic control, it’s beneficial to recognize the impact of physical activity on blood sugar levels.
Blood Glucose and the Role of Insulin
Blood glucose, or blood sugar, is the primary sugar found in your blood and is your body’s primary source of energy. Glucose is derived from your diet and released into your bloodstream.
When glucose enters the bloodstream, the pancreas releases insulin, and insulin allows glucose to enter the body’s cells to give them energy.
However, in T1D, the body cannot produce insulin due to the destruction of insulin-producing cells in the pancreas. Without insulin, glucose cannot enter the cells, leading to high blood sugar levels. High blood sugar, or hyperglycemia, can result in symptoms like feeling sick, blurred vision, abdominal pain, dehydration, and rapid heartbeat.
In contrast, low blood sugar, or hypoglycemia, is common during and after physical activity or prolonged periods without proper nutrition and can negatively impact an athlete’s performance and health. For individuals with T1D, the risk of hypoglycemia extends beyond the immediate post-exercise window, often occurring hours later or even overnight. This delayed drop in blood sugar can be caused by insufficient refueling after training or misjudging the insulin needed. These unpredictable glucose swings make it essential for athletes with T1D to carefully monitor their levels and adjust their strategies accordingly.
The Impact of Exercise on Blood Sugar
Aerobic exercise, such as running, cycling, or swimming, uses oxygen to produce energy over a longer duration. This tends to lower blood glucose because the body relies on oxygen for fuel. On the other hand, anaerobic exercise, like sprinting or weightlifting, involves short bursts of high-intensity activity that don’t require oxygen for energy. Instead, the body taps into glycogen stores, raising blood glucose due to stress hormones like adrenaline and cortisol. Since most sports involve a mix of both, consistent blood sugar monitoring before, during, and after exercise is critical.
Unique Responses to Exercise
Each athlete has a unique response to exercise, making blood sugar management even more difficult. Optimal blood sugar levels are individualized; therefore, blood sugar management techniques must be tailored to each athlete. For example, physical training increases insulin sensitivity, especially immediately after exercise, which can lead to hypoglycemia. However, research shows that many athletes with T1D still experience high blood sugar levels, often due to inadequate calorie intake rather than exercise alone. This highlights the importance of regularly monitoring glucose levels before, during, and after exercise and ensuring proper nutrition to maintain balance.
Symptoms of hypoglycemia to be aware of include shakiness, sweating, hunger pangs, and a flushed face. However, severe cases can lead to confusion, seizures, unconsciousness, or even death if not treated promptly. (If athletes end up experiencing hyperglycemia, all athlete support staff are advised to follow the American Diabetes Association (ADA) guidelines).
Managing Blood Sugar with Nutrition and Technology
Refueling with carbohydrates and protein within an hour of training or competition can replenish glycogen stores and promote muscle recovery. Since exercise enhances the body’s sensitivity to insulin, athletes with T1D must fuel throughout the day to avoid “bottoming out” or experiencing delayed onset hypoglycemia. Physical activity can cause blood sugar to drop unexpectedly, especially overnight, due to ongoing energy expenditure and the body’s recovery process.
Working with a sports nutritionist or registered dietitian (RD) is essential for effectively identifying patterns and managing these episodes. Continuous glucose monitors (CGMs), such as Dexcom, have also been a game-changer for many athletes with T1D. These devices provide real-time glucose data, allowing athletes, parents, and teammates to respond quickly to changes and prevent severe drops. They also help patients recognize long-term trends, understand how different factors impact their glucose levels, and ultimately achieve better control over their condition.
Automated Insulin Delivery Systems
Automated Insulin Delivery (AID) system reduces some guesswork in daily glycemic management. While automation offers flexibility, exercise poses challenges around the accuracy of continuous glucose monitoring (CGM) systems and the ability of AID systems to maintain glucose levels in the target range. This challenge arises from varying physiological responses to different types, intensities, and durations of exercise and individual differences in response to physical activity.
The Role of Pharmacists and Care Teams
Pharmacists play a significant role in initiating and maintaining patients on CGM devices. They can help determine the best CGM device based on patient-specific factors, analyze CGM data, and recommend medication adjustments (depending on state laws).
Managing diabetes in any athlete requires a team approach. Individualized management strategies should be created with close cooperation between the T1D athlete and their healthcare team (including a physician and dietitian). Diabetic athletes must communicate their treatment plan and history with coaches, trainers, and support personnel. Remember, every athlete’s response to exercise is unique and influenced by factors such as intensity, duration, time of day, and emotional stress.
Instead of athletes needing to explain their symptoms, coaches, staff, and teammates should be familiar with the signs of low blood sugar and adjust training accordingly to support the athlete’s safety and performance.
Together, a Diabetes Action Care Plan can be developed to meet the athlete’s specific needs. According to the National Athletic Trainers Association, this plan should include the following:
- Blood glucose monitoring guidelines
- Insulin therapy guidelines include the type of insulin used, dosages and adjustment strategies for planned activities, and insulin correction doses for high blood glucose levels.
- List of other medications
- Guidelines for hypoglycemia recognition and treatment
- Guidelines for hyperglycemia recognition and treatment
- Emergency contact information: parents’ and/ or other family members’ telephone numbers, physician’s telephone numbers, and consent for medical treatment (for minors).
- Athletes with diabetes should have a medic alert tag with them at all times.
- Athletes should keep sugary snacks on hand, drinks, and even possibly glucagon in the kit/action plan at all times.
Personalized Nutrition and Fueling Plans
Knowing what and when to eat is critical. According to the Academy of Nutrition and Dietetics, athletes should eat one to four hours before a workout. Athletes should focus on consuming carbs and protein within an hour of competition or practice. This allows muscles to replenish glycogen and helps muscles rebuild and repair with the available protein and amino acids. During practice or competition, consuming sports drinks or sugary snacks can be beneficial for maintaining blood sugar levels, especially during extended periods of activity. These quick sources of glucose can help prevent energy dips and support sustained performance.
Working with a sports dietitian or endocrinologist can help athletes create a personalized fueling plan to maintain stable glucose levels. A refuel plan can be developed to replenish glycogen and support recovery. Additionally, athletes can plan smaller snacks throughout the day, especially before bed, to prevent overnight lows.
Rising to the Challenge: Success Stories of Athletes with Diabetes
A notable figure among diabetic athletes is Gary Hall Jr., who was diagnosed with T1D at 25 years old. Hall Jr. faced one of the hardest decisions any athlete can make: taking a break. However, Hall Jr. recognized the importance of mastering his diabetic routine before he could return to the pool.
Long story short, Hall Jr. went on to win 5 Olympic medals (two gold medals) after his diagnosis in the 2000 and 2004 games. His diagnosis also paved the way for a successful post-swimming career in healthcare management, youth sports, and patient advocacy.
“I became the first athlete to medal with T1D. The team I had supporting me really empowered me. The way we managed my diabetes to achieve that success has changed what is now taught in medical school. There was no literature and very, very few resources available about how to manage diabetes in sports. There is much more now, but still not enough,” he shared in an interview with the International Olympic Committee.
Another standout athlete, Mandy Marquardt, is a world-class track cyclist who competes for both the USA Cycling National Team and Team Novo Nordisk, the world’s first all-diabetes professional cycling team; managing diabetes requires dedication year-round.
In 2020, she was named to the Olympic Track Cycling Long Team, a milestone in her journey as an athlete and an advocate for diabetes awareness.
“Being part of Team Novo Nordisk and the USA Cycling National Team has not only provided me a stage for racing a bicycle but also a platform to help others. Managing diabetes is 24/7, but I wouldn’t wish for it to be any other way,” Marquardt shared in a blog by the United States Anti-Doping Agency (USADA). It’s important to note that athletes who are on insulin and who compete in drug-tested sports require a Therapeutic Use Exemption (TUE) for drug-testing purposes, as insulin is classified as a banned substance unless medically necessary.
But this isn’t just impacting world-class athletes.
Collegiate-level athlete Jacob Hunter was first diagnosed with T1D when he was 11 years old and competes at the highest level on the UVA track and cross-country teams. In an interview with the University of Virginia, Hunter reflected on the mentality he has slowly adopted since his diagnosis.
“It was really frustrating because sports just meant so much to me. I didn’t feel like myself. But I am happy to look back at it now and see how I’ve grown from that moment. I didn’t let it hinder my ability to get back on my feet.”
Another NCAA superstar, Kate Hall, made a similar point in an interview with Runner’s World on the perception of athletes with diabetes.
“A lot of people think, oh, you have diabetes, you can’t really do a lot. That’s definitely a misconception because they can do anything they want to do. As long as you have control of the diseases, it can actually make you stronger. I wouldn’t be who I am today without it.”
For resources and tips, organizations like the Diabetes Exercise and Sports Association and the The National Athletic Trainers Association are great sources of information about best practices and how to best accommodate athletes with T1D.
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Written by Jessie Tobin, MA, BA
After receiving her master’s in professional communication, Jessie began her professional career at a healthcare technology startup, where she managed all content writing, paid media, email marketing and partner relationships. She is deeply passionate about using storytelling to build strong emotional connections between brands and their audiences, a skill she has refined through her YouTube channel, which has over 17 million views. Aside from copywriting, she shares her expertise as a professor at The University of Tampa.