If you have type 1 diabetes, staying active can help lower your chances of developing other complications. These can include high blood pressure, heart disease, nerve damage, and vision loss. Regular exercise may also help improve your overall quality of life.
Strenuous activity can cause your blood sugar to drop. This can lead to low blood sugar, which is called hypoglycemia. Intense bouts of exercise can also cause your blood sugar to rise. If it rises above normal levels, it’s known as hyperglycemia.
Take a moment to learn how you can exercise with type 1 diabetes while keeping your blood sugar in a safe range.
According to the American Diabetes Association (ADA), most adults with type 1 diabetes should aim to get at least 150 minutes of moderate- to vigorous-intensity aerobic exercise per week. Examples include swimming, cycling, jogging, walking, dancing, and playing team sports such as basketball or soccer.
The ADA also encourages adults with type 1 diabetes to complete two to three sessions of resistance activities per week. Resistance activities include muscle-strengthening workouts, such as weight lifting, resistance band exercises, and body-weight exercises.
Different workouts can affect your blood sugar in different ways, depending on the type, intensity, and duration of the exercise.
When you complete an aerobic activity, your blood sugar level is likely to drop. The longer the session, the more likely your blood sugar will drop.
Some research has found it may help to incorporate short sprints or high-intensity intervals into aerobic workouts to reduce the drop in your blood sugar level. For example, it may help to sprint for 5 seconds every 2 minutes during a 30-minute cycling session. While more research is needed, some findings suggest this vigorous activity may trigger the release of hormones that decrease the drop in blood sugar.
Studies also suggest that doing resistance activities before an aerobic workout may help keep your blood sugar steadier. For instance, consider lifting weights before you go for a jog or swim laps. On their own, resistance activities tend to cause smaller drops in blood sugar than aerobic exercises.
No matter what type of exercise you do, it’s important to check your blood sugar level before and after each workout. Coordinating your food and insulin intake with your workouts can help keep your blood sugar in the normal range.
Before you start a new exercise routine, it’s best to talk to your doctor or diabetes educator. They can help you learn which workouts are safe for you. They can also guide you on how to keep your blood sugar in a safe range by coordinating your meals, snacks, and medications with your routine.
To prevent low blood sugar during and after exercise, your doctor or diabetes educator might advise you to take one or more of the following steps:
- Reduce the amount of bolus or basal insulin that you take before, during, or after exercising.
- Increase the number of carbohydrates that you eat before, during, or after exercising.
- Incorporate sprints or high-intensity intervals into your aerobic workouts.
- Complete resistance activities before your aerobic workouts.
- Adjust the timing, intensity, or duration of your workouts.
To stay safe while exercising with type 1 diabetes, it’s helpful to:
- Check your blood sugar before and right after each workout. If you’re exercising for an extended period, check your blood sugar every 30 to 60 minutes during your workout, too.
- In the hours after your workout, recheck your blood sugar. Your blood sugar can continue to drop for several hours after exercise, which may cause delayed hypoglycemia.
- Pay attention to how your body feels while you’re exercising. If you start to feel sick, shaky, or confused, stop and check your blood sugar level.
- Finish your workout at least two hours before you go to bed. This may help prevent delayed hypoglycemia while you sleep.
- Avoid exercising when you’re sick or coping with an infection. This can affect how your body responds to physical activity.
- Have fast-acting carbohydrates available to treat low blood sugar that might develop during or after your workout. For example, carry glucose tablets, fruit juice, or non-diet soda with you.
- Exercise with a coach, trainer, or friend who knows that you have type 1 diabetes. Teach them how to recognize and treat severe hypoglycemia.
- Wear or carry medical identification that lets people know that you have type 1 diabetes. If you develop severe hypoglycemia, this can help them identify the treatment that you need.
- If your blood sugar is lower than 100 mg/dL (5.6 mmol/L) before you begin your workout, eat 15 to 30 grams of fast-acting carbohydrates before you start exercising. If you’re planning to workout for an hour or more, include some protein in your snack too.
If your blood sugar is higher than 250 mg/dL (13.9 mmol/L) before you start your workout, test your urine or blood for ketones. If you have a high level of ketones in your urine or blood, it’s not safe to exercise. Contact your doctor and follow their instructions to treat the elevated ketones.
If your blood sugar is higher than 250 mg/dL (13.9 mmol/L) but you have no ketones or only trace ketones in your urine or blood, you can proceed with your workout.
In most cases, exercise causes blood sugar to drop. But sometimes, short, intense bouts of exercise can cause your blood sugar to rise. This is due to the effects of stress hormones released during high-intensity activity.
If your blood sugar level is high before you begin your workout, check your blood sugar more frequently during and after your workout. Make sure that you drink plenty of water or other liquids to stay hydrated. Dehydration can increase your blood sugar concentration.
If your blood sugar level is still high after exercising, you can take a small bolus of rapid-acting insulin to lower it. If you use an insulin pump, you can temporarily increase your basal insulin infusion until your blood sugar returns to the normal range.
If your blood sugar rises higher than 250 mg/dL (13.9 mmol/L), measure the ketones in your urine or blood. If your ketone level is high, contact your doctor. Follow their treatment instructions and avoid vigorous activity until your blood sugar and ketone level returns to normal.
When you exercise, your body pulls sugar from your bloodstream to fuel the activity. It also draws on sugar stored as glycogen in your muscles and liver.
This is why your blood sugar level tends to drop during a workout. It’s common for blood sugar to continue to drop for several hours after exercise, too.
If your blood sugar level drops to 70 mg/dL (3.9 mmol/L) or lower, it’s known as low blood sugar, or hypoglycemia. In most cases, hypoglycemia can be easily treated by eating or drinking fast-acting carbohydrates. In severe cases, hypoglycemia must be treated with a medication known as glucagon.
When you take a dose of insulin, it signals the cells in your muscles, liver, and fat to absorb sugar from your bloodstream. This helps prevent your blood sugar from getting too high when you eat.
Taking too much insulin can cause low blood sugar, or hypoglycemia. Exercising can also cause your blood sugar to drop. That’s why it’s important to coordinate your insulin intake with your meals, snacks, and workouts.
To help prevent low blood sugar during and after workouts, your doctor or diabetes educator might advise you to reduce your insulin intake on days when you exercise.
It can take some trial and error to learn how your body responds to changes in your insulin intake, carbohydrate intake, and exercise routine.
Keep records of your insulin intake, food intake, exercise activities, and blood sugar to help you learn how to coordinate your medication, meals, and snacks on days you work out.
To treat hypoglycemia in its early stages, consume about 15 grams of fast-acting carbohydrates, such as:
- glucose tablets or glucose gel (follow the package directions for dosage)
- ½ cup of fruit juice or non-diet soft drink
- 1 tablespoon of sugar, dissolved in water
- 1 tablespoon of honey or corn syrup
- some hard candies or gumdrops
After eating or drinking 15 grams of fast-acting carbs, wait 15 minutes and check your blood sugar level again. If your blood sugar level is still 70 mg/dL or lower, eat or drink another 15 grams of fast-acting carbs. Repeat these steps until your blood sugar level returns to a normal range.
After your blood sugar returns to normal, eat a small snack with carbs and protein. This can help keep your blood sugar steady.
If left untreated, hypoglycemia can become severe. Severe hypoglycemia is a potentially life-threatening condition that can cause seizures and loss of consciousness.
If you develop seizures or loss of consciousness, you won’t be able to swallow any foods or drinks with fast-acting carbs safely. Instead, you'll need a medication known as glucagon.
Your doctor can give you a prescription for a glucagon emergency kit or glucagon nasal powder. Consider telling your coach, trainer, or workout buddy where to find your glucagon. Teach them when and how to use it in case of an emergency.
If your blood sugar is lower than 150 mg/dL (8.3 mmol/L) before your workout, eat a carbohydrate-rich snack to help keep your blood sugar up while you’re exercising.
Aim to eat about 15 to 30 grams of carbohydrates in your pre-workout snack.
If you’re planning to exercise for an hour or longer, include some protein in your snack, too.
Each of the following snacks typically contains about 15 grams of carbs:
- 1 cup of fruit
- ½ cup of fruit juice
- 1 cup of milk
- 1 cup of yogurt
- 1 slice of bread
- 5–6 crackers
- ½ cup of dried cereal
- 1 granola bar
These snacks typically contain about 15 grams of carbs, plus protein:
- 5–6 crackers plus 4 dice-size cubes of cheese
- 5–6 crackers plus 1 tablespoon of nut butter
- ½ sandwich with peanut butter, cheese, turkey, or other meat
- 1 cup of fresh fruit plus ¼ cup of cottage cheese
If you’re planning to exercise for an hour or more, check your blood sugar every 30 to 60 minutes. If your blood sugar drops below 100 mg/dL (5.6 mmol/L), take a break to snack on some carbs.
Check your blood sugar after your workout, too. If your blood sugar is low, eat some fast-acting carbs.
If you don’t have a meal scheduled within the next hour or so, eat a post-workout snack that contains both carbs and protein to help stabilize your blood sugar.
When it comes time to eat your next meal, be sure to include both carbs and protein. This will help replenish your body’s store of glycogen and promote muscle repair.
To support your overall health and well-being, take part in regular exercise, including aerobic and resistance activities.
Exercise tends to lower your blood sugar, which can lead to hypoglycemia. To prevent hypoglycemia, try reducing your insulin dosage on days when you exercise or eat more carbs before your workouts. You might also consider adjusting the exercise activities that you do.
Your doctor and dietitian can help you learn how to coordinate your medication, meals, snacks, and workouts to keep your blood sugar in a safe range.