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Sport and exercise

  • Keeping active is an important part of your diabetes management. All children with diabetes should be encouraged to participate in all sports and activities.  

    Having diabetes shouldn’t stop you from performing sports at your best!

    Being physically active is good for child and adolescent health, as well as being a great way to make friends and to develop physical and social skills.

    Children and young people aged 5-17 years should be physically active for a minimum of 60 minutes per day. 

    This can be accumulated during the day, for example:10 minutes before school, 20 minutes walking or riding to and from school, and 30 minutes of active play after school = 60 minutes.

    Even if children are physically active, they will still benefit from limiting the amount of time that they spend sitting or lying down (except when sleeping) in as many ways as possible.

    Use of screens and electronic media for entertainment should be limited to less than 2 hours per day.

    An uninterrupted sleep of 9 to 11 hours per night is recommended for those aged 5–13 years, and 8 to 10 hours per night for those aged 14–17 years. It is also important to have consistent bed and wake-up times.

    Reference: National Physical Activity, Sedentary Behaviour, and Sleep Recommendations for Children and Young People (5-17 years) available at

    How does exercise affect blood glucose levels (BGLs)?

    In general, exercise lowers blood glucose levels (BGLs). This is because your body uses glucose as an energy fuel, and muscle cells become more active. Everyone is individual and the response to exercise can vary from person to person. Management of your diabetes during exercise will depend on the type, duration and intensity of the exercise.

    To get a better understanding of your BGL response during exercise, it is important to keep a record of your BGLs and the different types of exercises performed.  This includes checking before, during and after exercise and noting the direction your BGLs are trending. It is important to aim for target BGLs (4.0-7.0 mmol/L) to maximise performance during exercise. 

    Hyperglycaemia before exercise can impact on your performance during exercise. Sometimes BGLs can rise just before or during an activity due to the release of a hormone called adrenaline. This is usually short lived, with BGLs returning to target range without requiring extra insulin.

    If your blood glucose is 15mmol/L or higher and your blood ketone level is 0.6 mmol/L or higher then activity should be postponed until blood ketones are less than 0.6 mmol/L.

    A general guide for managing exercise with diabetes

    As a general rule, for every 30-45 mins of moderate to vigorous physical activity (i.e. a game of netball/basketball or an active PE/sport lesson) you should consume one extra serve of carbohydrate (approximately 15 grams), preferably low GI. This is just a starting point; the amount of carbohydrate you require may differ depending on your level of fitness and the type and length of activity you are doing.

    Examples of 1 carb serve activity snacks: 

    • 1 medium piece of fruit 
    • 1 small tub of yoghurt 
    • 1 glass of milk 
    • 2 plain sweet biscuits 
    • 1 slice of bread 
    • 4-6 crackers 
    • 1 muesli bar 
    • 1 small tin of baked beans 

    It is usually best to have the extra carbohydrate 30 minutes before exercising, to allow the slow acting carbohydrate time to be absorbed by the body. This is in addition to the carbohydrate you usually have e.g. if sport is after a meal/snack.

    Exercise increases the muscles’ sensitivity to insulin and this is why insulin doses may need to be reduced if playing sport, even if you eat extra carbs. Discuss with your diabetes team if you are not sure if or how to reduce insulin doses.

    You do not need extra carbohydrate during recess and lunch breaks at school (even if you are very active). Your daily insulin doses and carbohydrate serves are based on your usual activity levels.    

    If you are doing long periods of high intensity activity then you might need to have extra fast acting (high GI) carbohydrate during the activity, e.g. sports drink or juice, and you may also need to reduce your night time insulin. Your diabetes team can advise you on this. 

    Delayed hypoglycaemia

    Delayed hypo’s can occur, often up to 12-16 hours after being active. This is because your muscles continue to use glucose during recovery and your body is more sensitive to insulin after exercise. 

    Monitoring BGL’s prior to bed and overnight is very important after prolonged exercise.

    If you are experiencing regular hypoglycaemia during or after activity then a reduction in insulin might be necessary – talk to your diabetes team about this.

    Importance of monitoring

    Exercise affects everyone differently. Monitor your BGLs carefully to look for patterns and learn how your body responds to different sports. Monitoring your BGLs before activity is important and can give you an idea as to which direction your BGLs are heading and how much extra carbohydrate you require


    • Short duration high intensity activities (e.g. sprints, weight lifting) may not require additional carbohydrate intake prior to the activity, but may produce a delayed drop in BGL. For these activities, extra carbohydrate may be needed after the activity
    • Longer duration lower intensity activities (e.g. soccer, football, basketball, bike riding, jogging, swimming) will usually require extra carbohydrate before and possibly during/after the activity OR changes to insulin doses
    • The dose of insulin which is acting at the time of the exercise (especially rapid acting) may need to be reduced by 20-50%
    • Less carbohydrate may be needed if insulin has been reduced before the activity
    • Injecting in the stomach or hips is preferable prior to exercise
    • Monitor BGLs several hours after exercise including before bed and overnight between 2-3am