The benefits of exercise are wide ranging. Regular physical activity can help people manage their weight, sleep better, reduce the risk of some diseases, including type 2 diabetes (T2D) and heart disease, and improve overall quality of life—among other proven benefits.
People with type 1 diabetes (T1D) can gain the same benefits from exercise as anyone else. Yet studies show that many people with T1D do not engage in regular physical activity owing to a fear of hypoglycemia, or dangerously low blood-glucose levels.
Exercise scientists and athletes with T1D alike say that people with T1D can exercise safely and effectively. It’s a matter of observing how your body responds to exercise, learning to balance insulin, food, and physical activity, and using research-supported strategies to minimize the risk of hypoglycemia during and after exercise.
Sheri Colberg-Ochs, Ph.D., professor of exercise science at Old Dominion University in Norfolk, VA, has both professional and personal interests in understanding the risks and benefits of exercise for people with T1D. As an exercise physiologist, Dr. Colberg-Ochs studies the relationship of exercise to diabetes and lifestyle management. She has also lived with T1D for 44 years, while staying fit and active.
Dr. Colberg-Ochs notes that the risk of hypoglycemia during and after exercise can be managed. “There’s not a tried and true method that works for everyone. It’s very individual, based on the type of activity and your normal diabetes regimen,” she says, “but you can certainly reduce the frequency of hypoglycemia that’s associated with being physically active.”
The risk of hypoglycemia is affected by the type, duration, and intensity of physical activity. Aerobic activities, such as a long, moderately paced run or swim, will likely reduce blood sugar. Other activities, like a short, all-out sprint or weight lifting, can raise blood-sugar levels because they trigger a response in the body from hormones such as adrenaline that release stored glucose from the liver. Similarly, an athlete’s blood-sugar level can increase during a competition because of the adrenaline response, even though practicing or training for the same sport, which is usually less stressful than competition, might have the opposite result and lower the athlete’s blood sugar.
An individual with T1D might need to start preparing an hour or two before beginning an activity to ensure that his or her insulin is balanced at an appropriate level to avoid hypoglycemia during the exercise and simultaneously avoid excessively high blood glucose, or hyperglycemia. Dr. Colberg-Ochs explains that, in general, a prolonged bout of exercise with high insulin levels in the blood is more likely to result in hypoglycemia. “The key is to get the circulating insulin levels as low as possible [while avoiding hyperglycemia], because that is more physiologically normal during physical activity,” she states.
Preparations for exercise might include adjusting short-acting insulin doses or the basal rate on a pump or eating to compensate for a recent insulin injection, depending on the nature of the planned activity and the individual’s prior response to exercise.
Simple strategies to prevent immediate post-exercise fall in blood glucose were discovered by Paul Fournier, Ph.D., and Timothy Jones, M.D., of the University of Western Australia in Perth. In JDRF-supported research, they showed that people with T1D who performed four-second sprints at maximal effort every two minutes during high-intensity exercise did not experience a drop in glucose levels after exercise. Further, performing a 10-second sprint before or after moderate activity helped to prevent an immediate drop in blood glucose after exercise.
Dr. Colberg-Ochs suggests that post-exercise recovery drinks can also be an effective tool to avoid immediate hypoglycemia. Whole milk is one of the best options after exercise because its mix of carbohydrates, protein, and fat is metabolized slowly, helping to stabilize blood glucose over time.
People with T1D might also experience delayed-onset hypoglycemia, when blood sugar falls 7 to 11 hours after physical activity—often in the middle of the night. Strategies to prevent delayed hypoglycemia include adjusting basal insulin infusions before bedtime, for those using an insulin pump, or eating a late snack.
It is important for people with T1D to understand that exercise-associated hypoglycemia is manageable. According to Dr. Colberg-Ochs, “one of the best things people can do is self-monitor to establish their response to different activities, times of the day, and so forth so they can make changes to their diabetes regimen. But being physically inactive is probably a bigger risk than being active in terms of long-term health.”
When John Rueth, 50, of Waukegan, IL, was diagnosed with T1D at 15 years of age, his doctor advised him to find a career that would involve a lot of walking and exercise every day. This, the doctor suggested, could help prolong his life and maintain his overall health.
Now, John is constantly on the move as a health and physical education teacher at Daniel Wright Junior High School in Lincolnshire, IL, and a golf coach for the neighboring high school. John also stays active outside of school by playing basketball, mountain biking, and racing all-terrain vehicles.
“For me, exercise is the key,” John explains. “I try to do at least 10,000 steps every day by walking around in the classroom and fitness center, and I think it truly helps out.”
After 35 years with T1D, John has not experienced any diabetes complications—an outcome he credits to his active lifestyle. John’s personal experience is backed up by research. George King, M.D., principal investigator of the JDRF-supported Joslin 50-Year Medalist Study, has reported that being physically active is associated with reduced risk of complications in individuals who have lived with T1D for 50 years or longer.
Like everyone with T1D, John had to discover through trial and error how his body responds to exercise. For example, his blood sugar is apt to crash suddenly about 1.5 to 3 hours after physical activity. John has also learned that his blood sugar drops more quickly when he plays golf in hot and humid weather compared to milder conditions. He knows to monitor himself more closely during those times and to take appropriate action, such as consuming extra carbohydrates, to prevent hypoglycemia.
The importance of exercise is a lesson that John wants to pass on to the next generation. He openly shares his knowledge with all of his young students who have T1D, so that they can better understand and manage their own reactions to exercise. In April, John organized a JDRF Kids Walk to Cure Diabetes at his junior high school, leading 750 students on a walk around the school grounds and raising $10,000 in the process. John explained the difference between T1D and T2D and educated the students on the importance of exercise and nutrition. The day was a terrific success, the kids asking questions about John’s experience with T1D and participating in the Walk with enthusiasm. He says, “I was really excited and pleased with the kids and how much they supported the effort.”
For others with T1D, John advises, “don’t be afraid of exercise. You are going to have some highs and lows, but you will figure it out. The benefits are just unbelievable if you keep your body active, and I think that with type 1 diabetes, it’s even more important—that’s my personal philosophy.”
Turner Rapp, 18, of St. Louis, MO, does not let T1D stop him from pursuing his love of sports, despite the challenges. “I understand that the prospect of exercising with type 1 diabetes may be intimidating. There’s a period when you have to learn how your blood sugar reacts and how your body reacts, because it’s very different from person to person,” Turner says. “But I think that most people with type 1 diabetes who exercise regularly realize that their blood sugar is ultimately better for it.”
Turner, who was diagnosed with T1D at age 10, recently graduated from high school, where he participated in several competitive sports. He found that each activity, including running, cycling, tennis, and golf, requires a different approach.
Before a 5K run, Turner might check his blood sugar eight times in two hours, making many small adjustments until his glucose is exactly where he’s comfortable. A short race doesn’t allow time for eating, so he reduces his insulin dose during the event according to his experience of how his blood sugar is likely to react. He checks his glucose level again immediately after the race and eats something if it is too low. A cycling event might last for hours, but as a competitor, Turner cannot get off his bike to check his blood sugar. Instead, he carries carbohydrates to eat at regular, planned intervals—again, based on his personal knowledge of how his body reacts on long bike rides. In contrast, tennis matches and golf games are not limited by time, so Turner can monitor himself during an event and adjust his insulin and food intake as needed.
The effects of exercise do not end when the race or game is over. Turner has found that his blood sugar often drops between 11 p.m. and 2 a.m. Knowing this, he adjusts the basal rate on his pump to deliver less insulin in those hours, and, if necessary, he eats an extra snack.
Although Turner now has an excellent handle on his body’s response to exercise, he also keeps a strong support network around him during athletic events. He makes a point of talking with his coaches and teammates about T1D—a good idea for all active teenagers with T1D. “I think the best approach is to be open about your diabetes,” Turner suggests. “That way, everyone’s watching out for you.”
In July, Turner and a team of supporters participated in his fourth “century ride” (100 miles in one day) at the JDRF Ride to Cure Diabetes in Burlington, VT. Turner, who has also taken part in JDRF Rides in Death Valley, CA, and Kansas City, MO, recommends the Ride to everyone who wants to challenge him- or herself. “I think the Ride is a great and sometimes life-changing opportunity for people with diabetes looking to set a fitness goal and raise money for JDRF.”
Exercising with T1D requires extra care, but with the right support and knowledge, it doesn’t have to be overwhelming. Joe Largay, PA-C, CDE, a physician assistant and researcher at the University of North Carolina Diabetes Care Center in Durham, NC, treats individuals with T1D every day. As an athlete who has lived with T1D for 26 years, Joe shares his knowledge of the challenges and benefits of exercise, which he considers an integral part of T1D management.
“Just like the rest of the population, people with type 1 diabetes are becoming overweight and obese. They need to know the dangers of that and the health benefits of an active lifestyle,” he explains. Joe works closely with individuals who have a range of athletic skills—from people just getting started to those who participate in elite, high-endurance events like the Ironman Triathlons—teaching them to exercise safely while maintaining control of their blood glucose.
Joe advises having a medical checkup before starting an exercise program, as some activities are not recommended for people with certain T1D complications. People with the most advanced form of diabetic eye disease, known as proliferative retinopathy, should avoid exercises that raise blood pressure, such as high-intensity aerobic activity or lifting heavy weights. Those with nerve damage, or neuropathy, should inspect their feet daily for blisters or nonhealing wounds. For people with neuropathy, non-weight-bearing activities, such as swimming, water aerobics, or cycling on a stationary bike, are preferred over activities that are more stressful on the feet, such as jogging.
For anyone who wants to start exercising, consistency and good record-keeping are essential. “In the beginning, try to do about the same amount of activity at the same time of day, and keep records,” Joe suggests, “because you can have a different response to exercise in the morning versus when you get out of work in the afternoon.” He also asks people in his practice to check their blood sugar before and after exercise to monitor how they are affected by different activities or conditions like stress or the adrenaline rush of a competition.
People should start with an enjoyable activity that they are more likely to stick with over time. It is also advisable to periodically review those exercise records with a healthcare provider who can explain how to adjust insulin dosing and food intake in order to minimize high and low blood glucose episodes during and after exercise.
In Joe’s experience at the Diabetes Care Center, most people with T1D who exercise feel better overall and have an improved sense of well-being. He says, “I try to get my patients to realize that with diabetes you can still lead a long, healthy, active lifestyle, if you are willing to take care of it.”
Exercising with T1D requires personalized adjustments to daily T1D management, and many resources are available to help guide and educate anyone who wants to get moving. Healthcare professionals, including certified diabetes educators and registered dietitians with expertise in nutrition and exercise, can provide essential information for starting or managing an exercise program.
The Diabetic Athlete’s Handbook, written by Dr. Colberg-Ochs, is another valuable resource. The book describes the latest research on diabetes and exercise, personal experiences of 350 exercisers with T1D or T2D, and diabetes management tips for more than 100 different sports and activities.
Making a commitment to a healthy, active lifestyle may help people with T1D reduce the risk of certain diseases, lower daily insulin requirements, prevent diabetes complications, and have a higher quality of life. With a willingness to learn and adjust, a person with T1D can exercise safely and enjoy the rewards.
The information in this article is offered for general educational purposes and is not intended to replace professional medical advice. You should not make any changes to the management of type 1 diabetes without first consulting your physician or other qualified medical professional.