More than 18,000 new cases of type 1 diabetes are diagnosed each year in people age 20 and younger. It is no secret that exercise and physical activity are important for all kids, especially for youth with diabetes. Not only do exercise and physical activity improve blood glucose control in kids with type 1 compared to being sedentary (engaging in fewer than 30 minutes a day of activity), but they also improve blood cholesterol and blood pressure, lower body fat content, increase bone and muscle fitness, and improve well-being.
Sports are a big part of our culture. Most U.S. high schools have organized team sports, and these activities can become highly competitive as early as middle school. When youth with type 1 diabetes are athletic, it is key that parents help their children learn to plan ahead to assure they have the opportunity to be their best athletic selves.
If your child is an athlete and has type 1 diabetes, you will need to help him/her balance several factors to enable optimal performance during athletic endeavors. Whether he/she is a competitive or recreational athlete, it is important to optimize both athletic performance and blood glucose levels. Exercise often is more complicated when children are treated with insulin because muscle contractions during activity will cause muscles to take up more blood glucose, which can lead to hypoglycemia (low blood glucose).
The type of athletic activity can affect blood glucose response, as can the time and duration of exercise and the order of activities. Activities that involve aerobic, sprint, or resistance training can result in widely varying blood glucose responses. Many times, your child’s insulin doses and food intake will need to be adjusted to prevent hypoglycemia or hyperglycemia (high blood glucose) before, during and/or after activity.
As a parent, consider these issues if your child is an athlete with diabetes who wants to perform optimally. If your child feels better, he/she will perform well, so it is imperative that blood glucose levels are in a normal or near normal range during both training/practice and competition.
Avoiding highs and lows
Hypoglycemia (a blood glucose level of 70 mg/dl or lower) can impair your child’s athletic performance and well-being. Hypoglycemia is more likely to occur during exercise when insulin levels in your child’s body are too high and can occur in children with type 1 diabetes who have to inject or pump insulin. Hypoglycemia also can affect levels of blood electrolytes such as potassium, that may reduce performance for hours afterwards. You also will want to keep close surveillance on your child’s blood glucose levels and watch out for exercise-induced hypoglycemia, which can occur up to 48 hours after an activity.
When insulin is used as part of the diabetes treatment plan, it often is tempting to allow blood glucose to run too high to prevent hypoglycemia. However, hyperglycemia (a blood glucose level of 240 mg/dl or higher) can be detrimental to athletic performance. When blood glucose levels go above 200 mg/dl, your child will start spilling some glucose from his/her blood into the urine, which upsets the delicate balance of electrolytes such as potassium, sodium, chloride and magnesium in the blood. Electrolyte imbalances can impair muscle function and performance.
In particular, if your child has type 1 diabetes, make sure to check for ketones if he/she has unexplained hyperglycemia. If blood glucose and ketone levels are too high, your child likely will need to postpone exercise because blood glucose and ketones can rise even higher with physical activity. Talk with your child’s diabetes care team and have a plan in place regarding hyperglycemia with ketones with clear parameters around when not to exercise.
The effects of exercise type, order and timing
Most sports require different types of training and practices in addition to games and competitions. In some cases, adding high-intensity intervals to a moderate aerobic workout may help prevent hypoglycemia, at least in the short run. In fact, some intense activities actually raise blood glucose temporarily by increasing hormones such as adrenaline and glucagon, which raise blood glucose levels. So a brief (10-second) sprint either before or after an exercise session of moderate intensity may help protect against hypoglycemia. Keep in mind that blood glucose levels tend to decline less during resistance training such as weight, dumbbell or resistance band than during aerobic activity such as jogging or swimming. If your child is engaging in both types of training, you both may want to choose which type is done first based on starting blood glucose level.
Many sports require intense training sessions to help strength and endurance. Consider the timing of workouts and the influence on blood glucose control. Exercising first thing in the morning before breakfast likely will help your child keep blood glucose levels more stable, since everyone is more insulin resistant (and usually with lower insulin levels) at that time of day. In fact, his/her blood glucose may go up doing the same activity in the morning, even if it normally causes a decrease in blood glucose when done later in the day. Some athletes have to take a small dose of rapid-acting insulin after working out to lower their blood glucose levels following morning exercise. If your child has frequent episodes of hypoglycemia during workouts, consider morning training sessions. Conversely, if your child’s levels run high during workouts, choose training later in the day. Short-term athletic performance in intense activities such as sprinting also tends to be better in the afternoon than in the morning.
Adjusting food and insulin for optimal performance
For a competitive advantage in sporting events, your child will have to prevent both hypoglycemia and hyperglycemia during and following the events. Hypoglycemia in particular makes it hard to perform well, but blood glucose levels can be managed effectively with strategic carbohydrate intake and adjustments in the timing and doses of insulin. To prevent hypoglycemia during activities lasting 30 minutes or more, he/she may need extra carbohydrate, less insulin, or both.
If your child’s injected or pumped insulin levels are minimal when he/she begins exercising, he/she may need only 10 to 15 grams of carbohydrate to prevent hypoglycemia. When exercising within two hours of bolus insulin for a meal or snack, he/she may need closer to 30 to 60 grams of carbohydrate per hour of exercise. This is similar to the amount of carbohydrate athletes without diabetes need for optimal athletic performance, and everyone can benefit from carbohydrate during workouts or events lasting several hours. After a workout, the muscle’s storage of carbohydrate builds back up slowly. During this time, your child likely will be more sensitive to insulin. This can contribute to hypoglycemia, which can occur up to a day or two later. Taking in adequate amounts of carbohydrate along with enough insulin (although usually less than normal) before, during and after longer moderate-intensity or high-intensity workouts can help minimize the chances of hypoglycemia.
In place of or in addition to taking in carbohydrates to maintain blood glucose levels during exercise, your child’s basal (background) insulin and bolus (mealtime) insulin doses may need to be lowered to decrease his/her hypoglycemia risk. Talk with your diabetes care team about your child’s individual needs. In some cases, up to a 20% reduction in basal insulin both before and after exercise (especially overnight following prolonged activities) is necessary. If your child uses an insulin pump, he/she may need to reduce or suspend basal insulin infusion at the start of exercise, or even 30 to 60 minutes beforehand, to prevent hypoglycemia. If your child exercises within two to three hours of a meal or bolus dose of insulin, he/she may need to cut back the dose by 25% to 75%. Your diabetes care team can help determine what insulin adjustments are necessary. Regardless of your child’s regimen changes, be sure to check his/her blood glucose frequently and make additional adjustments to stay in target range.
Using insulin pumps, CGM
If your child is very active in sports, one advantage of an insulin pump over multiple daily injections is that a pump allows both you and your child to change hourly basal insulin delivery when he/she exercises to bring blood glucose closer to normal. If your child injects basal insulin once or twice a day with a syringe or a pen, you will be less able to respond quickly to changes in insulin needs related to athletic activity. In unpredictable situations, for example, if a baseball game goes into extra innings, your child will have better control over basal rates with a pump than if a basal insulin injection was given several hours earlier. If your child does wear a pump and is active in outdoor sports, keep in mind that heat exposure has the potential to make insulin in the pump stop working effectively.
A recent advance in glucose monitoring is the use of continuous glucose monitors (CGM). In some cases, CGM is a sort of map, monitoring glucose trends every several minutes during exercise and detecting hypoglycemia afterwards. For some devices, CGM does not replace self-monitoring of blood glucose, which still is needed to confirm the results. In these cases, checking blood glucose is a must whenever the child feels symptoms of either hypoglycemia or hyperglycemia. (The Dexcom G6 and FreeStyle Libre do not require finger-sticks to make treatment decisions.) Keep in mind CGM also has a time lag between actual blood glucose and its detection, since the sensor measures glucose in the skin (not the blood). Talk with your child’s diabetes care team to see if this option may be helpful.
Heat and exercise performance
Whether indoors or outside, athletic activities cause most people to break out in sweat. Some athletes with type 1 diabetes have impaired sweating, particularly during higher intensity activity such as sporting events/competitions. Be sure your child has comfortable, breathable clothing to help him/her stay as cool as possible. It is extremely important to avoid dehydration, which can further lower your child’s sweating and cooling ability. If activities are outside in hot weather, staying hydrated is essential to avoid becoming overheated. Cool, plain water usually is adequate for hydration during moderate exercise for up to one hour. Sports drinks containing electrolytes may be used during longer, more intense types of exercise. They typically contain carbohydrate, so be mindful of the serving size on the Nutrition Facts label to help calculate the amount of carbohydrate. It is best to avoid fruit juice and regular soda because they may upset the stomach, causing cramps, bloating and nausea.
Helping your student athlete manage blood glucose can be complicated but successful — and well worth the effort. How hard your child exercises, the type of sport and time of day, food intake, and insulin levels all affect blood glucose responses and athletic performance. Be aware of all these factors, along with the importance of staying hydrated and keeping electrolytes in balance.
Stay focused on your child’s diabetes health with routine appointments with the diabetes care team. Ask questions so you and your child can best manage his/her athletic endeavors. Helping your child manage his/her diabetes effectively to succeed during exercise is important, whether your child is a competitive athlete or simply a recreational sports and exercise enthusiast.
Want to learn more about caring for a child with Type 1 diabetes? Read “Type 1 Diabetes and Sleepovers or Field Trips,” “Writing a Section 504 Plan for Diabetes,” and “Top 10 Tips for Better Blood Glucose Control.”