Being physically active is one of the mainstays for staying healthy — and not just for people who have diabetes. There are countless reasons for and benefits of being active. But having type 1 diabetes can sometimes feel like a barrier: How do you handle insulin and food? How do you prevent hypoglycemia (low blood sugar)? For some, it can feel like becoming and staying active is too much to bother with, and too complicated to figure out.
Benefits of being active
Your diabetes care team has likely reinforced why being physically active is so important for your health. Being active can make it a lot easier to manage your blood glucose levels. Sure, what you eat and taking your insulin as prescribed play a big role, but exercise is also part of the equation. Exercise can also lower the risk of certain diabetes-related complications, including heart disease and stroke.
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But there are so many more benefits to being active, aside from having better blood sugars. Research shows that regular exercise can help you:
• Manage your weight
• Lower your cholesterol and blood pressure
• Sleep better
• Strengthen your bones and muscles
• Improve your mood
• Better handle stress
• Ease anxiety and depression
• Lower your risk of some types of cancer
• Reduce your risk of falls
• Have more energy during the day
• Live longer
Risks of being active
Physical activity is not without risk. Muscle or ligament strain, twisting an ankle or falling are potential types of injuries, depending on the type of activity that you do. Excessive exercise may exacerbate underlying heart problems in some people, which is why it’s crucial to check with your healthcare provider before starting any type of exercise program.
The most common risk of physical activity with type 1 diabetes is hypoglycemia. The risk, however, depends on the timing, duration and intensity of the activity. Also, the risk of hypoglycemia is higher in people who are just starting an exercise program compared with people who exercise regularly.
Other factors may increase the chance of hypoglycemia during exercise — these include not eating enough carbohydrate, not adjusting insulin, not monitoring blood glucose sufficiently and exercising in hot weather.
Types of physical activity
There are three main types of physical activity to aim to include in your routine:
This type of activity helps strengthen your heart, improve your stamina, burn calories and lower blood pressure. Walking, jogging, cycling, swimming and dancing are types of aerobic activity.
Strength training (sometimes called resistance training) helps strengthen muscles and increases muscle mass. At the same time, this type of activity can strengthen your bones, improve balance and posture, lower blood sugars and help relieve joint and back pain. Weightlifting, using resistance bands or weight machines, and calisthenics are examples of strength training.
Stretching helps you stay flexible, which, in turn, lessens the chance of muscle cramps and strain, joint pain and even falling. Being flexible also makes it easier to do the activities of daily living, such as tying your shoes or scratching your back. Check out these examples of stretching exercises.
Frequency, duration and intensity
If you’re just getting started with a physical activity program, it’s always important to ease into a routine and follow recommendations from your healthcare provider or diabetes educator. This means starting slowly and gradually working your way up. Going full throttle greatly raises the chance of injury and hypoglycemia, as well as fatigue and discouragement.
Frequency of exercise
Aiming to be active most days of the week is the goal. When you exercise, blood glucose levels are more easily managed, and the effect can last for 24 to 72 hours afterwards.
Duration of exercise
If you’re new to exercise, you may be able to do 5 or 10 minutes of physical activity as you get started (and every amount that you do is beneficial). Again, as you get acclimated to a more regular routine, aiming for at least 30 minutes of physical activity is the goal. If you’re trying to lose weight, 60 to 90 minutes per session is the goal. If that sounds next to impossible, keep in mind that you don’t have to exercise for 30, 60 or 90 minutes all at once; it’s OK to break it up into smaller sessions.
How hard you exercise depends on your level of physical fitness, as well as other health conditions that you have. In general, though, you can use the “talk test” as a good gauge: you should be able to carry on a conversation while you are exercising. If you can’t, you’re working out too hard.
Blood glucose monitoring for exercise
Physical activity affects everyone differently. That’s why it’s so important to monitor your glucose levels frequently around physical activity, especially when you are just starting out. Monitoring helps you understand your body’s response to the activity that you do. Whether you use a meter or CGM (continuous glucose monitoring), you need information about what your glucose is doing and where it might be headed in order to know how to proceed. Monitoring before, during and after exercise is recommended.
Starting glucose level for exercise
Hopefully you’re checking your blood sugars several times a day already, or maybe using CGM, which gives you glucose readings about every five minutes. Knowing your glucose level before you start moving is essential; otherwise, you may end up with hypoglycemia or maybe even hyperglycemia (high blood sugar).
Mid-point glucose level for exercise
It’s possible that your glucose level will drop rather quickly while you’re exercising — again, this depends on how much insulin you have on board, as well as the intensity of your workout. On the other hand, you may find that your glucose levels start to climb while you’re exercising; this can happen if your starting glucose was high to begin with, or if you’re doing high-intensity exercise, which may cause the release of stress hormones that raise glucose levels.
Ending glucose level for exercise
You may find that exercise lowers your glucose levels — that’s a good thing, right? Yes and no. Exercise can lower glucose levels — but sometimes glucose levels drop hours after you’ve stopped, including in the middle of the night. This happens because your liver and your muscles draw glucose from the blood to replenish their glucose stores.
Always make sure you carry hypoglycemia treatment with you when you work out. It’s also a good idea to wear or carry some form of medical identification, and to let someone know where you’re going, especially if you’ll be exercising alone.
Exercise blood glucose goals
Here are some general guidelines for glucose goals before you start to exercise. Once again, your goals may be different, so discuss your glucose targets with your doctor or diabetes educator.
Glucose is lower than 100 mg/dl
If your glucose is below 100 before you start exercising, there’s a pretty high risk of hypoglycemia. For safety reasons, it’s best to eat a snack that contains about 15 grams of carbohydrate, such as a small piece of fruit. Doing so will give your glucose a bit of a boost and lessen the chance of a glucose drop, especially if you recently took insulin and/or will be exercising for 30 minutes or longer. Also, if your glucose is below 80 before you exercise, treat the low with 15 grams of carbohydrate, and don’t exercise until your glucose has risen to a safe level.
Glucose is 100 to 250 mg/dl
For many people this is the target glucose range, pre-exercise. Of course, there’s no guarantee that your glucose won’t go too low while you’re working out, but it’s less likely that you will, especially if you’re recently eaten a meal or a snack. If you use a CGM, you will be alerted if your glucose level is trending downward, which is a great safety feature for those with type 1.
Glucose is above 250 mg/dl
Here’s where caution should come into play. When your glucose is above 250, break out the ketone strips and check to see if you have ketones in your urine. If you do, don’t exercise. The presence of ketones means that your body doesn’t have enough insulin on board, and you’re at risk of developing DKA (diabetic ketoacidosis). If you don’t have ketones, you feel well, and your glucose is high because you, say, ate a handful of cookies a few hours ago, then it’s likely safe to exercise.
Through trial and error and with guidance from your diabetes care team, you can learn to adjust your insulin for exercise. While some people prefer to exercise after eating a meal or snack to reduce the risk of hypoglycemia, that may not always be possible: the best time to exercise is when it’s best for you. Also, you might prefer not to have to consume additional carbohydrate prior to your workout.
But which insulin do you adjust? In general, if you’ll be exercising after a meal, you can likely reduce the amount of mealtime insulin that you take. If you’ll be exercising before a meal or first thing in the morning, it’s probably better to eat a carbohydrate snack; however, if you’ll be doing longer-duration exercise, such as skiing or hiking, then you will likely need to reduce your longer-acting (basal) insulin. And if you use an insulin pump, work with your diabetes educator to determine if adjustments in your bolus doses are needed or if using a temporary basal rate is the best course of action for you. You can see how considering the type, timing and duration of your exercise is so important.
There’s a lot to think about and plan for when you have type 1 diabetes, and exercise is no exception. However, don’t let all of that planning and monitoring deter you. There are a lot of people with type 1 diabetes who exercise successfully (including athletes). Be patient, work with your diabetes team and stay the course. The benefits are worth it!
Want to learn more about exercising with diabetes? Read “Add Movement to Your Life,” “Picking the Right Activity to Meet Your Fitness Goals” and “Seven Ways to Have Fun Exercising.”