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Exercise guidelines
This information booklet outlines the factors you need to consider when being physically active or doing exercise. It includes guidance on adjustments you may need to consider making to help you manage it safely. It is important to note that these guidelines are a starting point and will need
to be adjusted to suit your individual response.
Exercise has many benefits for both physical and mental health.
The current recommendations are:
- Aim to be physically active every day.
- Do at least 150 minutes of moderate intensity activity a week. That is anything that raises your heart rate, such as a brisk walk.
- Include strengthening activities that work all the muscles on at least two days of the week, for example a body weight workout or heavy gardening (digging or shoveling)
What counts as physical activity and exercise
When talking about exercise, often people think of sports like football, squash, cycling and running, or going to the gym and gym classes. It is important to remember other activities like gardening, housework, shopping and a night out dancing, all of which will affect your blood glucose levels.
Glucose response to different types of exercise in Type 1 diabetes
You may have noticed that different exercises have a different effect on your blood glucose levels.
Which exercise generally results in a drop in blood glucose level?
Aerobic exercise, which is exercise that increases heart and breathing rate over a sustained period.
Examples of aerobic exercise include:
- Walking
- Jogging/steady running
- Steady cycling
- An aerobics/gym class
- Gardening
- Dancing
- Swimming
Which exercise generally results in a rise in blood glucose level?
Anaerobic exercise, which is generally short, intense bursts of activity. These types of anaerobic activities cause the body to release hormones such as adrenaline, glucagon and cortisol, which can result in a rise in blood glucose level.
Examples of anaerobic exercise include:
- Weight training
- High intensity interval training
- Exercise that includes short bursts of activity such as squash
- Sports competitions
Team sports, such as football, hockey and netball can include both aerobic and anaerobic activity due to the frequent changes in the intensity of play and can cause blood glucose levels to either increase or decrease.
If you notice a rise in your blood glucose after a certain exercise or activity, you can either take no action, as the blood glucose level may reduce after the activity is complete. Or you can give 50% of your usual correction dose at your next meal
All activity, whether aerobic or anaerobic will increase risk of hypoglycaemia in the hours after completing the activity.
Hypoglycaemia and exercise
Being physically active can increase the risk of hypoglycaemia both during and after the activity. This is due to the following:
- During the activity the body uses glycogen stored in muscles for energy. This glycogen then has to be replaced by glucose from the blood.
- Exercise causes your body to become more sensitive to insulin.
This increased risk of hypoglycaemia can last for up to 24 hours after the activity has occurred. If the exercise has been prolonged or was very vigorous the risk of hypoglycaemia can last for up to 48 hours.
You are more likely to experience a hypo if:
- You have had a hypo in the previous 24-48 hours.
- You have had a severe hypo where you have required help from someone else. If this is the case, you should not exercise for the following 24 hours. This is because your stores of glycogen (which converts to glucose) will be depleted.
- You have started a new exercise.
Tips to help avoid hypoglycaemia during exercise
- Monitor your blood glucose levels before, during and after exercise.
- Ensure you are well hydrated prior to exercising and stay hydrated during exercise.
- Always carry rapid acting carbohydrates with you e.g. jelly babies, dextrose tablets or sports gels.
- Take additional carbohydrates before exercising if blood or sensor glucose is <7mmol/l. See page 10 for further information.
- Follow the guidance on reducing insulin doses around activity and exercise which is on the following pages of this booklet.
- Consider the timing of your most recent quick acting insulin doses. Hypoglycaemia is less likely to occur when you have the least amount of active insulin in your system. This is usually the first thing in the morning before breakfast or 4 hours after your last dose of quick acting insulin.
Target blood glucose at start of exercise
A blood glucose of 7-15mmol/l is considered a safe range for your blood glucose level to be before commencing exercise.
The table on the following page will help guide you as to what action to take depending on your blood glucose levels.
If you are using a libre or continuous glucose monitor the arrows can help guide, you as to what action you need to take.
Managing glucose levels before exercise
| If you have had a severe hypo in the last 24 hours do not exercise | ||
| Blood glucose level | Action | |
| >15mmol/l | Check ketones |
No ketones
|
|
Ketones - trace (0.6-1.5 mmol/l blood ketones)
|
||
|
Ketones - more than a trace (>1.5 mmol/l blood ketones)
|
||
| 7.0 - 15.0 mmol/l | Proceed to exercise | |
| 5.7 - 6.9 mmol/l | Have 15g rapid acting carbs | Proceed to exercise |
| 3.5 - 5.6 mmol/l | Have 20g rapid acting carbs |
|
| <3.5 mmol/l | Have 20g rapid acting carbs |
|
Using the arrows to help guide you
If you are using CGM or flash glucose monitoring, you can use the arrows to help guide you on how much additional carbohydrate you should take before and during exercise:
| Blood glucose level | Libre arrow | Amount of carbohydrate |
| 3.5 - 5.6 mmol/l |  |
10g |
 |
15g | |
 |
20g | |
 |
25g | |
 |
30g |
| Blood glucose level | Libre arrow | Amount of carbohydrate |
| 5.7 - 6.9 mmol/l | |
8g |
|
11g | |
|
15g | |
|
19g | |
|
23g |
Blood glucose level 7 - 15 mmol/l - Continue to monitor regularly during the activity.
Note: the sensor data can change every 10 minutes and may not be as accurate if the levels are changing rapidly during exercise
During exercise you may like to consider increasing your low alert to 5.5 mmol/l
Managing blood glucose levels during and after exercise
There are 3 strategies for managing blood glucose levels during and after exercise
- Reduce insulin
- Increasing carbohydrate intake
- Change the type of exercise
Insulin adjustment for exercise
Adjustment of quick acting insulin
It is not possible to give exact dose adjustments as this will vary from person to person. However, a good place to start is:
Reduce dose of quick acting insulin by 50% if the activity is occurring within 2 hours of the dose being given. This applies to any dose of quick acting insulin given up to two hours before and after exercise and for any correction dose.
For example: You are going to meet a friend for a one hour walk an hour after eating your evening meal. You would usually give 6 units for that particular meal but knowing that you are going to be doing an hour of exercise within two hours of this dose, you reduce your dose of quick acting
insulin to 3 units.
If you are more familiar with the effect exercise has on your blood glucose levels, you may want to consider varying the reduction based on the activity duration and type. The table below can be used as a guide.
| % Dose reduction | ||
| Exercise intensity | 30 minutes of exercise | 60 minutes of exercise |
| Low | 25% | 50% |
| Medium | 50% | 75% |
| High | 75% | 100% |
Reduction of basal insulin
The changes suggested below only apply if you are using a basal insulin regimen twice a day such as Levemir.
A 20% reduction of the night time basal insulin dose is recommended if any of the following apply:
- Exercise has taken place after 4pm
- The exercise lasted longer than 2 hours
- High intensity exercise occurs at any time of the day
- You have tried out a new form of exercise during that day
If the exercise is prolonged, for example a day’s shopping, a day’s hiking or a day of DIY, a 50% reduction in basal insulin taken before and after the exercise should be considered. You may also need to make a further 20% reduction the following morning.
If you are using a once-a-day basal insulin regimen any adjustments do not take effect soon enough, therefore strategies including reducing quick acting insulin and increasing carbohydrate intake should be used.
Increasing carbohydrate
If the exercise is unplanned, you may not have the option of adjusting insulin doses, in which case taking extra carbohydrate is an alternative approach.
A good starting point is to take an extra 0.5g carbohydrate/kg of body weight/hour of exercise.
For example, a 60kg person walking for an hour would take 30g of extra carbohydrate, ideally spread out across the hour as 10g every 20 minutes.
The following table gives examples of suitable carbohydrates you could try
| Carbohydrate source | 10g carbohydrate | 15g carbohydrate | 30g carbohydrate |
| Jelly babies (large) | 2 | 3 | 6 |
| Jellybeans | 6 | 9 | 18 |
| Cola | 100mls | 150mls (mini can) | 300mls |
| Apple juice | 80mls | 120mls | 240mls |
| Lucozade sport drink | 200mls | 230mls | 500ml bottle |
Drip feeding the carbohydrate in every 20 minutes leads to more stable blood glucose levels than having a larger amount in one go. This is known as ‘the drizzle effect’.
0.5g of carbohydrate/kg is a starting point and you may find you need to adjust this depending on the intensity and duration of the exercise, and the blood glucose results you get.
Changing exercise type
As was discussed earlier in this booklet different exercises have a different effect on blood glucose levels. In general, anaerobic exercises can cause blood glucose levels to increase initially. Whereas aerobic exercise will result in blood glucose levels decreasing. Changing the type of exercise can be
used in the following ways:
- Adding a short walk or jog at the end of an anaerobic workout such as a squash match or weightlifting session can help to counteract the rise in blood glucose levels.
Adding a couple of 10 second sprints at the end of long run can help increase blood glucose levels in the short term
Summary
You may decide to use one of the strategies discussed in this booklet, or you may find you need to use two or all the strategies.
These are only guidelines, and it is important that you monitor your blood glucose levels before, during and after exercise to work out what is an effective strategy for the activity and exercises you do.
Other key factors to remember:
- Ensure you are adequately hydrated before exercise and maintain good hydration during and after exercise.
- Always carry hypo treatment with you when doing any kind of physical activity or exercise. Examples of good hypo treatments are:
- 150-200mls of fruit juice or full sugar cola
- 4-5 large Jelly babies
- 5-6 dextrose tablets
- Consider exercising with another person, especially if you are at higher risk of hypoglycaemia. It is also a good idea to carry your phone with you.
If you would like any further advice on managing physical activity or exercise, please discuss this with your diabetes specialist dietitian.
Useful resources
• www.
• https://
• https://
Contact us
If you have any queries relating to this information, please contact the Dietetics service.
About this information
Service:
Dietetics
Reference:
DT/024
Approval date:
31 October 2023
Review date:
30 October 2026
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Important note
This page provides general information only. It is developed by clinical staff and is reviewed regularly every 3 years for accuracy. For personal advice about your health, or if you have any concerns, please speak to your doctor.