Managing planned activity and exercise using Hybrid Closed Loop (HCL) systems

You will find a detailed guide to understanding different types of activity on the website.  

What happens to your glucose levels during physical activity and exercise will depend on: 

1. The type of exercise/activity you are doing 
2. How much insulin you have on board – IOB or insulin on board or active insulin 
3. Your glucose number and trend 
4. The time of day and time of exercise 

It helps you to manage your glucose levels during exercise if you understand each of the factors.

Exercise/activity type. Exercise can have different impacts on glucose levels. It is important that you know how your glucose levels change during the exercise you do. As a guide we divide exercise into 3 types, Aerobic, Anaerobic and Mixed activity.

Insulin on board. Insulin on board (IOB) is insulin that has been delivered and is working in the body. Each system will tell you how much insulin is on board. You may see this called active insulin or IOB. You need to understand what this means for you when you are being active.

• Too much insulin on board can cause hypos. 
• Too little insulin in the body can cause highs.  

HCL systems can adjust insulin delivery, but you may need to help them out during exercise.  

Glucose number and trends. Glucose levels before exercise can help to predict what may happen during your activity. The sensor arrow is also important. Glucose levels that are falling mean greater risk of lows during exercise. If glucose levels are rising, there may a lower risk of lows during exercise. 

The number, trend and IOB can all be used to help manage glucose levels during activity. 

Time of day and timing of exercise. When you exercise is important. 

• Exercise in the morning before eating has a lower risk of hypos than the same activity in the afternoon or evening.  
• Aerobic activity (exercise that lowers glucose levels) within 2 hours of a meal or snack with insulin is more likely to cause hypos/low glucose levels.  

The table below is a general guide to what may happen to your glucose levels during exercise, how your insulin needs may change and if additional carbohydrate (carbs) may be needed. Keeping a record of what happens to your glucose levels will help you to learn how different training sessions or sports impact you.

Exercise tips
	Post meal aerobic or prolonged exercise	Mixed activity, individual and team sports	Early morning exercise, anaerobic activity, competition
Glucose response
Insulin requirements
Carb requirements

Adapted from https://easd-elearning.eu/wp-content/uploads/2024/12/EASD_Exercise_and_AID.png 

General principles

When you are doing planned activity on a hybrid closed loop system there are some general guidelines you should follow. 

1. Set a higher glucose target 1 -2 hours before the activity starts if the activity usually lowers glucose levels (aerobic activity).  
2. Aim for a low insulin on board at the start of activity that usually lowers glucose levels. 
3. If activity usually raises glucose levels maintain usual insulin on board. 
4. Always check if the system is delivering insulin or paused before you begin the activity. If insulin delivery is already paused, you will need carbohydrate snacks during aerobic exercise.
5. Use carbohydrate snacks if needed aiming to maintain the system target glucose for activity. 
6. Always have fast acting carbohydrate snacks available during activity. 
7. Adjust hypoglycaemia treatment amounts to avoid hyperglycaemia (high glucose levels) as this can cause rebound hypos on HCL systems. 
8. When activity that usually lowers glucose levels is 1-2 hours after meals, start the higher glucose target (activity setting) before the meal. If needed reduce the meal bolus by 25 -33%. 
9. If activity usually raises glucose levels give the usual bolus with the meal before. 
10. Drink plenty to stay hydrated. 
11. Always have a blood glucose and blood ketone meter available during the activity.

Exercise within 2 hours of insulin bolus

If glucose level is 7mmol/l or below consume exercise snacks before starting activity. Use your trend arrow to guide the amount of carbohydrate (carb).

Check every 20- 30 minute and repeat carbohydrate snacks as needed. If your glucose falls you need more, if your glucose levels rise you need less carbohydrate.

Before and during your activity

Adjust your insulin delivery based on your starting glucose levels and type of activity. Follow the information below.

See the system specific sections for how to follow this advice for the HCL system you are using.

Maintaining glucose levels during exercise may need additional exercise carbohydrate as well as insulin or glucose target adjustments if the activity is after a meal.

Before you start your activity checklist 

• Check your insulin on board (IOB) or active insulin
• Check your sensor arrows
• Check your system to see what the pump is doing – has it paused insulin delivery

This will help you decide if you need extra carbs to prevent low glucose levels.

You will still need to check your glucose levels and trend arrow to decide if you need extra carbs during exercise even if you have adjusted insulin or the system is adjusting insulin.

After activity

• Check your insulin on board (IOB) or active insulin
• Check your sensor arrows
• Check your system to see what the pump is doing – has it paused insulin delivery

Exercise settings should be stopped at the end of the activity unless you usually go low after exercising then you may need to use your higher exercise target for longer or start using your exercise target if you didn’t need it during the activity

If you have high levels after exercising you may need to think about stopping the higher exercise target before the end of the activity.

You may also need to adjust the amount of insulin with any food eaten after exercise.

Start by using the advice in the table and contact the team for help and support.

How does the Omnipod 5 work?

Automated insulin delivery happens when the pod and Dexcom are connected. During exercise you don’t need your controller for automated insulin, but you do need it for food boluses and corrections. Your controller needs to be within 1.5m of the pod for you to be able to see data.

The adaptive basal delivery adjusts your insulin every 5 minutes based on your predicted glucose levels in 60minutes time.

When you are using the activity setting the system will aim to keep your glucose levels at 8.3mmol/L and will reduce insulin delivery by about 50%.

• For exercise that usually lowers glucose levels start the activity setting 1-2hours before the activity.
  • Exercise that lowers glucose levels 1 -2 hours after a meal, try turning on activity mode before the meal before the activity.
  • If needed reduce the meal bolus by 25%
• For exercise that usually raises glucose levels a target of 6.1mmol/L is recommended. If the usual target is 6.7mmol/L or above, consider setting a lower target.
  • Give the usual meal bolus before exercise that raises glucose levels

Illustration of how to set and cancel the Activity feature on the Omnipod 5 system

Moser et al (2024) Diabetologia DOI 10.1007/s00125-024-06308-z
_{©The international Society of Pediatric and Adolescent Diabetes and the European Association for the Study of Diabetes 2024. Distributed under the terms of the CC BY 4.0 Attribution License (http://creativecommons.org/licenses/by/4.0)}

Recommendations for use of the Omnipod 5 system to manage glucose outcomes during physical activity

Moser et al (2024) Diabetologia DOI 10.1007/s00125-024-06308-z
_{©The international Society of Pediatric and Adolescent Diabetes and the European Association for the Study of Diabetes 2024. Distributed under the terms of the CC BY 4.0 Attribution License (http://creativecommons.org/licenses/by/4.0)}

To check what the system is doing before and during activity, tap sensor graph and rotate the controller to view.

If the system has paused insulin delivery and your glucose level is falling you may need to have more frequent small snacks. Aim to snack to keep your glucose level around 8.3mmol/L if activity mode is on.

How does Control IQ work?

Control IQ predicts glucose levels 30 minutes ahead and adjusts insulin every 5 minutes based on these predictions. The automatic insulin delivery is based on the programmed basal rates. The most important setting for influencing the algorithm is the correction factor. The system uses a treatment target range of 6.2 and 8.9mmol/L and will give auto corrections once an hour to bring glucose levels back to a target of 6.1mmol/L. Exercise activity mode ‘raises’ the floor and changes the target range to 7.8 -8.9mmol/L.  

When using Exercise mode, Control-IQ technology will decrease the insulin delivery when the glucose level is predicted to be below 7.8 mmol/l 30 minutes in the future and will increase the insulin delivery when the glucose is predicted to be above 8.9 mmol/l 30 minutes in the future. If the glucose prediction 30 min in the future is expected to exceed 10.0 mmol/l, an automated correction bolus equivalent to 60% of the dose calculated by the insulin sensitivity factor will be delivered up to once per hour, if no user-initiated bolus has been given in the last hour. An automated correction bolus will not occur within 60 min of any bolus (of any amount) that has been delivered or cancelled.

• For exercise that usually lowers glucose levels start the exercise activity setting 1–2 hours before the activity.
  • Exercise that lowers glucose levels 1–2 hours after a meal, try turning on activity mode before the meal before the activity.
  • If needed reduce the meal bolus by 25%.
  • Give a small manual bolus before exercise to prevent automatic correction bolus in the next hour. 
• For exercise that usually raises glucose levels give the usual bolus with the meal before exercise. Exercise activity mode may not be needed.   
• Consider setting exercise specific profiles.  
  • For exercise that usually lowers glucose levels set a new profile with a weaker correction factor (ISF) this will help exercise activity reduce insulin for hypo prevention. 
  • For exercise that usually raises glucose levels set up a new profile with a stronger correction factor (ISF).

Illustration of how to set the Exercise mode on the t:slim X2 Control I-IQ system        

Moser et al (2024) Diabetologia DOI 10.1007/s00125-024-06308-z
_{©The international Society of Pediatric and Adolescent Diabetes and the European Association for the Study of Diabetes 2024. Distributed under the terms of the CC BY 4.0 Attribution License (http://creativecommons.org/licenses/by/4.0)}

Recommendations for use of the t:slim X2 Control I-IQ system to manage glucose outcomes during physical activity 

Moser et al (2024) Diabetologia DOI 10.1007/s00125-024-06308-z
_{©The international Society of Pediatric and Adolescent Diabetes and the European Association for the Study of Diabetes 2024. Distributed under the terms of the CC BY 4.0 Attribution License (http://creativecommons.org/licenses/by/4.0)}

Before exercise

To check what the system is doing before and during activity look for the symbols below on the pump screen.

How does auto mode work?

Auto mode adjusts insulin based on the glucose target (5.5, 6.1 and 6.7mmol/L or Temp target, exercise mode 8.3mmol/L) and predicted glucose values. The system will give auto corrections when the algorithm has been delivering auto basal at the maximum insulin limit, the sensor glucose is above 6.7mmol/L and the calculated correction bolus is more than 10% of the maximum insulin limit. When the temp target is turned on automatic corrections are turned off.

Insulin on board is displayed as Active Insulin and includes any meal bolus, manual correction and automatic correction boluses. Active insulin is used in the calculation of correction boluses.

For exercise that usually lowers glucose levels start the exercise temp target setting 1–2 hours before the activity.

Exercise that lowers glucose levels 1–2 hours after a meal, try turning on temp target before the meal before the activity.

If needed reduce the meal bolus by 25% – always have temp target on when reducing the meal boluses.

For exercise that usually raises glucose levels give the usual bolus with the meal before exercise. The temp target may not be needed. For exercise that usually raises glucose levels a target of 5.5mmol/L is recommended.

Illustration of how to set and cancel the Temp Target on the MiniMed 780G system

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Moser et al (2024) Diabetologia DOI 10.1007/s00125-024-06308-z
_{©The international Society of Pediatric and Adolescent Diabetes and the European Association for the Study of Diabetes 2024. Distributed under the terms of the CC BY 4.0 Attribution License (http://creativecommons.org/licenses/by/4.0)}

Recommendations for use of the MiniMEd 780G system to manage glucose outcpmees during physical activity

*img*

Moser et al (2024) Diabetologia DOI 10.1007/s00125-024-06308-z
_{©The international Society of Pediatric and Adolescent Diabetes and the European Association for the Study of Diabetes 2024. Distributed under the terms of the CC BY 4.0 Attribution License (http://creativecommons.org/licenses/by/4.0)}

Before exercise

You can see when the pump has suspended the insulin delivery by

1. pressing the diamond button
2. when there is a gap in the pink, magenta line, it means the pump is not delivering insulin.

*img*

The mylife CamAPS FX system allows personal glucose targets between 4.4 and 11mmol/L. Insulin delivery in auto mode is based on the algorithm. Any bolus given through the bolus calculator counts towards Insulin on Board which is called Active Insulin on the display.

The system has 2 settings to adjust insulin delivery.

Ease off mode which raises the glucose target and suspends insulin delivery if glucose levels are below 7mmol/L .

Boost which increases the insulin delivery in response to high glucose levels by up to 35%

When you use Ease Off and Boost, they do not impact the algorithm “learning’. For regular exercise using different personal glucose targets will influence how the system adapts.

• For exercise that usually lowers glucose levels use Ease-off from 2 hours before the activity.
  • Exercise that lowers glucose levels 1–2 hours after a meal, use Ease-off from before the meal
  • A higher glucose target can be used for exercise that usually lowers glucose levels. Change the personal glucose target to 8.3mmol/L 2 hours before the exercise session
  • If needed, you can reduce meal insulin dose by 25% for meals eaten 60 minutes before exercise.
• The Add meal function can be used to announce meals and snacks before exercise.
  • Use the hypoglycaemia treatment setting when entering carbohydrate snacks before and during exercise to prevent insulin delivery increasing.
• For regular exercise at the same time of day consider a profile with a higher personal glucose 2hours before the start of the activity.
• For exercise that usually raises glucose levels
  • Give the usual bolus with the meal before exercise.
  • Start boost at the beginning of the activity
  • Consider using a lower glucose target during the activity

Illustration of how to set a new personal glucose target and how to set the Ease-off (now or later) mode when using the mylife CamAPS FX system

Moser et al (2024) Diabetologia DOI 10.1007/s00125-024-06308-z
_{©The international Society of Pediatric and Adolescent Diabetes and the European Association for the Study of Diabetes 2024. Distributed under the terms of the CC BY 4.0 Attribution License (http://creativecommons.org/licenses/by/4.0)}

Recommendations for use of the mylife CamAPS FX system to manage glucose outcomes during physical activity

Moser et al (2024) Diabetologia DOI 10.1007/s00125-024-06308-z
_{©The international Society of Pediatric and Adolescent Diabetes and the European Association for the Study of Diabetes 2024. Distributed under the terms of the CC BY 4.0 Attribution License (http://creativecommons.org/licenses/by/4.0)}

If you would like advice or support with managing physical activity, contact the team for an appointment in the exercise and diabetes clinic.

This clinic is held on Friday mornings and we offer in person or virtual appointments. We can also offer appointments to sports coaches and anyone involved in supporting you with your activity. Email us at uclh.cddietitians@nhs.net to request an appointment.

General advice and explanations about how activity affects your glucose levels can be found on Digibete.

Consensus Guidelines Rights and Permissions

This article is licensed under a Creative Commons Attribution 4.0 International License – no changes were made to the figures.

Moser O and Zaharieva DP et al. (2024) Diabetologia DOI 10.1007/s00125-024-06308-z
© The International Society of Pediatric and Adolescent Diabetes and the European Association for the Study of Diabetes 2024. Distributed under the terms of the CC BY 4.0 Attribution License (http://creativecommons.org/licenses/by/4.0/)

References

1. Moser O, Zaharieva DP, Adolfsson P, Battelino T, Bracken RM, Buckingham BA, et al. The use of automated insulin delivery around physical activity and exercise in type 1 diabetes: a position statement of the European Association for the Study of Diabetes (EASD) and the International Society for Pediatric and Adolescent Diabetes (ISPAD). Diabetologia. 2024.
2. World Health Organisation (WHO). Global Recommendations on physical activity for health: WHO; 2010