As Registered Dietitian and Medtronic Diabetes Clinical Manager, Nancy Lea, rings in the New Year, she anticipates her yoga studio will go from slightly overcrowded to masses of bodies crammed into tight rows. Their mats will be only inches apart from one another as they sweat and struggle through a 90-minute class. Exercise is essential to her well-being and can be a healthy part of anyone’s life, including people with type 1 diabetes. However, some people with type 1 diabetes avoid engaging in regular activity, due to wearing an insulin pump or fear of hypoglycemia. Today, Nancy addresses some of the most common concerns about exercising with type 1 diabetes and an insulin pump.
Exercising with an Insulin Pump
“Will wearing an insulin pump limit my ability to exercise?” is among the most common questions I am asked in my role as a Diabetes Clinical Manager. The MiniMed insulin pump gives you flexibility for insulin dosing adjustments during short durations of exercise and for prolonged periods of time. The Enlite or Sof-sensor used for continuous glucose monitoring (CGM) provides your sensor glucose (SG) data to help you see your glucose trends prior to, during, and after you’ve finished exercising. To learn how different types of activities affect you, use your CGM to monitor your sensor glucose levels, and check your blood glucose (BG) using your BG meter before, during, and after exercising.
The risk of hypoglycemia associated with physical activity depends on the type, duration, and intensity of the exercise, and should be managed during and after physical activity. Some individuals may need to prepare an hour or two before beginning an activity to ensure their glucose levels are at a safe level. It all just depends on your body. Talk to your healthcare team about the type of exercise you’ll be engaging in, and how to best manage your insulin regimen prior to making adjustments on your own.
If you pump with the MiniMed 530G system, the Threshold Suspend feature automatically stops insulin delivery when your sensor glucose values reach a preset low threshold.
When you’re going to be physically active, it’s always a good idea to carry 15 grams of fast-acting carbohydrates, such as 4ounces of orange juice, 3-4 glucose tablets, or 5 lifesavers, and have them easily accessible. If you’re exercising between meals, check your BG prior to starting your activity. If your BG is lower than you’d like it to be, you may want to adjust your basal insulin using the Temporary Basal setting (but follow your healthcare team’s guidance), or eat a small snack consisting of 15 grams carbohydrates, such as crackers, an apple, or a slice of whole wheat toast. If your BG is below 50 mg/dL, try aiming for 20 grams of carbohydrates.
Considering Timing and Duration for Insulin Adjustments
Consider timing and duration when adjusting your insulin dosage, and always follow your healthcare team’s recommendations. The time of day you exercise may affect your insulin needs. For example, in the morning, BG levels tend to decrease less with exercise because of hormones at that time of the day that help raise BG levels, so you may exercise while making insulin adjustments as instructed by your healthcare team. However, in the afternoon, levels of the same hormone fall, so you may need to temporarily reduce your basal insulin delivery to prevent hypoglycemia.
Prolonged activities (90 minutes or longer), such as a moderately paced run or swim, may reduce your BG. Therefore, a temporarily basal insulin adjustment may be needed. According to the Managing insulin therapy during exercise in Type 1 diabetes mellitus research, a recommended starting point is setting a temp basal rate at 50% of your normal or standard basal rate for one to two hours before starting your activity is a recommended starting point. (1) On the other hand, short duration exercises, such as short-sprints or weight lifting, may raise your BG because they trigger hormones, such as adrenaline, that release stored glucose from your liver. Therefore, short duration exercises may not require adjustments to basal insulin. It’s important to consult with your healthcare team prior to making any adjustments to find what works best for you.
Adjusting Mealtime Bolus Insulin
According to the ADA and Robert Walsh, author of Pumping Insulin, if you’re eating within 90 minutes of exercising, you may need to reduce your mealtime bolus insulin to help maintain an optimal BG. Below are a few examples of adjustments that have worked for some of my patients based on the intensity and duration of their exercise. (2,3) Remember, it is important to work with your healthcare provider. Like insulin-to-carbohydrate ratios, when it comes to insulin and exercise, one size does not fit all. Finding the right balance does require some trial and error.
- Low intensity, less than 60 minutes: consider a 10%-20% bolus reduction
- Moderate intensity, more than 60 minutes: consider a 50% bolus reduction
- High intensity, less than 60 minutes: consider a 50% bolus reduction
- High intensity exercise, more than 60 minutes: consider a 70% or greater bolus reduction
Disconnecting from Your Pump
Whether or not you disconnect from your insulin pump depends on your body’s response to activity and the type of activity you’re doing. There are some instances when the pump must come off, such as swimming, surfing, or other water activities. There may be cases when there’s a good deal of physical contact where removing your pump may prevent damaging it. If you decide to disconnect from your pump, consider variables such as time, duration of disconnect, and exercise intensity. This will help determine your insulin adjustment, if needed. If you’re disconnecting for less than 60 minutes, replacement of basal insulin is usually not needed. If you’re disconnecting for longer than 60 minutes, consider reconnecting after 60 minutes, and administering 50% of your normal basal insulin rate as a bolus. As always, speak with your healthcare professional about a plan for replacing insulin that you did not receive while disconnected from your pump.
Managing High Blood Glucose
What happens when you go to exercise, but your BG is elevated? If your BG is far out of your target range (250 mg/dL or above), check for ketones. Performance may be somewhat impaired during hyperglycemia. However, if ketones are not present, it is generally safe to exercise. Be sure to talk to your healthcare team before starting an exercise routine to determine what works best for you. Remember to drink plenty of fluids, and Robert Walsh, author of Pumping Insulin, recommends considering giving 50% of the recommended Bolus Wizard correction bolus prior to exercise. (3)
Utilizing Taping Methods during Exercise
There are a wide variety of infusion sets and taping methods available for pump users. If you are having difficulty with your infusion set coming off during activity, place it on the body where the skin will not sweat or pull excessively, perhaps the arms or buttocks. You can use additional tape such as Tegaderm or IV 3000 and wear tight fitting garments over the infusion set to help the infusion set stay inserted.
I encourage you to share these tips, comment below, and most importantly, discuss with your health care provider and diabetes team. Whether you are embarking on a New Year’s Resolution to exercise more, planning your next outdoor adventure, or training for a distance race, I wish you all the best for a happy and healthy 2015!
Important Safety Information
Medtronic Diabetes insulin infusion pumps, continuous glucose monitoring systems and associated components are limited to sale by or on the order of a physician and should only be used under the direction of a healthcare professional familiar with the risks associated with the use of these systems. MiniMed 530G with Enlite is intended for the delivery of insulin and continuous glucose monitoring for the management of diabetes mellitus by persons 16 years of age or older who require insulin.
Pump therapy is not recommended for people who are unwilling or unable to perform a minimum of four blood glucose tests per day. Insulin pumps use rapid-acting insulin. If your insulin delivery is interrupted for any reason, you must be prepared to replace the missed insulin immediately.
The information provided by CGM systems is intended to supplement, not replace, blood glucose information obtained using a home glucose meter. A confirmatory fingerstick is required prior to making adjustments to diabetes therapy. MiniMed 530G with Enlite is not intended to be used directly for preventing or treating hypoglycemia but to suspend insulin delivery when the user is unable to respond to the Threshold Suspend alarm and take measures to prevent or treat hypoglycemia themselves.
Please visit www.medtronicdiabetes.com/importantsafetyinformation for more details.
WARNING: The Threshold Suspend feature will cause the pump to temporarily suspend insulin delivery for two hours when the sensor glucose reaches a set threshold. Under some conditions of use the pump can suspend again resulting in very limited insulin delivery. Prolonged suspension can increase the risk of serious hyperglycemia, ketosis, and ketoacidosis. Before using the Threshold Suspend feature, it is important to read the Threshold Suspend information in the MiniMed 530G System User Guide and discuss proper use of the Threshold Suspend feature with your healthcare provider.
1) Toni, et al. Managing insulin therapy during exercise in Type 1 diabetes mellitus, Acta biomed, 2006; 77; suppl. 1:34-40.
2) Bolderman, et al. Putting Your Patients on the Pump, Chapter 7, Alexandria Virginia: American Diabetes Association, 2012.
3) Walsh, Roberts. Pumping Insulin, 5th Edition, Chapter 22, San Diego, CA: Torre Pines Press, 2000.
, continuous glucose monitoring
, insulin pump therapy
, MiniMed 530G
, New Year's resolutions