Who is the leaflet for?
This information leaflet is for patients who have an insulin pump.
What is the aim of this leaflet?
The aim of this leaflet is to help explain why different sports have different effects on the blood glucose levels and some tips which you might find useful.
Can I exercise?
Yes, absolutely. Being on an insulin pump should not stop you exercising and achieving your goals providing there are no medical reasons why you have been advised not to.
Hopefully, your insulin pump will allow you to be more creative and flexible with your diabetes management but try not to give up if your blood glucose levels are unpredictable. This is frustrating but entirely normal. There is no such thing as a perfect strategy that will work for you every time so try not to feel that you have failed when your glucose levels don’t do what you expected them to do.
Effects of exercise on blood glucose levels
Most people find that different exercises will affect glucose levels in different ways. Low to moderate intensity exercise tends to lower the glucose levels. This can be referred to as aerobic activity. This happens because your muscles are using up the glucose in your body for energy. Your body stores glucose in the muscles and liver. The longer the exercise, the more likely it is that your glucose levels will drop because you are using up your stores of glucose. Exercising muscles take up glucose at a higher rate which also contributes to this lowering effect.
High intensity exercise tends to increase the glucose levels. This can be referred to as anaerobic activity. During anaerobic activity your body tends to produce a surge of hormones, such as adrenaline, causing the glucose levels to rise. You may also notice your glucose levels rising if you are in a competitive environment, for example, during a race, match, day of an event etc. Lactic acid which is often produced during high intensity exercise can also increase glucose production.
For one person, going for a 30 minute brisk walk may be aerobic. For somebody less conditioned to walking this may push them into the anaerobic system. This means that the effect on the glucose levels will be different from person to person.
The first step of coming up with a strategy to help you manage exercise is to try to optimise your pump settings on non-exercise days so you can get your basal rates and bolus calculator suited to your requirements. Your pump educator will be able to help you with this.
The second step is testing and monitoring your levels before, during and after exercise to work out what is happening to your levels during different exercises. You may find that going to the gym to weight train on one day will have a completely different effect on your glucose levels than running on the treadmill. This means that you may need a different strategy to manage your exercise on different days.
Where to start
A sensible target range for blood glucose level at the start of exercise is 7-10mmols/l. Different people feel comfortable exercising at different levels, they may prefer to start a little higher if they are new to the exercise and are not sure which way their glucose levels will go. The table below offers a guide of how to aim for a safe level of glucose before starting your exercise session.
Blood glucose | Recommendations (rule of thumb) |
---|---|
Blood glucose Less than 5.6mmol/L |
Recommendations (rule of thumb)
Eat 20g of glucose before exercise Delay exercise until blood glucose >5.6mmols/L |
Blood glucose 5.7-6.9mmol/L |
Recommendations (rule of thumb)
Ingest 15g of glucose Exercise can be started |
Blood glucose 7-15mmol/L | Recommendations (rule of thumb) Exercise can be started |
Blood glucose More than 15mmol/L |
Recommendations (rule of thumb)
Check blood ketones. · If ketones greater than 1.5mmols/L You should absolutely not exercise until ketones have cleared. · If ketones less than or equal to 1.5mmol/L This should be corrected with insulin (cautiously) and only mild exercise restricted to 30 minutes should be attempted if necessary. Monitor glucose and ketones closely. |
Blood glucose | Recommendations (rule of thumb) © Rob Andrews 2017 /DAFNE |
Exercising after a hypo- knowing the risk
We are all reluctant to delay or reschedule exercise when it has been planned into the day. For many it’s an important part of their relaxation, training regime or even part of their job. However, the advice is to avoid exercising altogether if you have had a severe hypo in the last 24 hours. A ‘severe hypo’ is a hypo requiring third party assistance (someone else treating the hypo for you). The reason for this is because research has found that your body is at far greater risk of another hypo if you have already had one in the last 24 hours. One study found that people exercising after a hypo needed three times more glucose infused into their body than somebody who had not had a hypo. They have found that your body is less able to produce the hormone response needed to keep your glucose levels topped up during exercise following a hypo.
There is some evidence to suggest that if you are an afternoon or evening exerciser, you might be at higher risk of hypoglycaemia the following day compared to if you were to do the same exercise but in the morning. This is probably due to the hormonal shifts in your body at different times of the day. This might be worth considering if you have noticed a pattern of evening exercise followed by a pattern of hypoglycaemia the following day.
Low blood glucose (Less than 3.5mmol/L) |
---|
Low blood glucose (Less than 3.5mmol/L)
Severe hypoglycaemia (needed help) **Don’t exercise for 24 hours** |
Low blood glucose (Less than 3.5mmol/L)
Self-treated hypoglycaemia Be careful for 24 hours If it occurs before exercise, treat and have stable glucose for 60 minutes before starting If it occurs during exercise, stop, treat and recommence after stable for 45 minutes |
Low blood glucose (Less than 3.5mmol/L) © Rob Andrews 2017 |
Tips for managing the pump
This is the question asked the most by people keen to exercise or to start exercising. Frustratingly there is not one strategy that will work every time. It takes a lot of experimentation and practice to understand what insulin adjustments and/or carbohydrate consumption that will work for you. Monitoring before, during (every 30 minutes) and after the exercise and recording/uploading your data will help you track your progress and decide what strategies are working. Never forget your pump team is on hand to offer a fresh perspective and work with you on this. The most valuable thing we can learn from is you and your experiences.
Step 1: Try to find a pattern of glucose trends (if there is one) with different workouts and note it down. Remember, if it doesn’t work well it’s not a failure.
Whatever the glucose data you get can be banked as useful experience in helping you find a better strategy for next time.
Step 2: Try using Insulin, Carbohydrates and/or Exercise (ICE). ICE looks at the three ways of managing your glucose during exercise. Insulin (I), Carbohydrates (C) and/or Exercise (E).
Insulin
Bolus insulin
It is best to avoid exercising when there is active insulin working in your body from a previous bolus. This helps to avoid hypos from exercising when your insulin is at its peak action which is usually one to two hours after taking it. Insulin can also reduce your liver’s ability to release glucose into the bloodstream during exercise, so the further away from a bolus of insulin the better the liver will be able to top up the glucose if necessary.
Exercising in a fasted state has been shown to improve predictability of glucose levels during exercise compared to exercising after a meal. This may not always be practical or possible so you may need to look at reducing the insulin you take with a meal prior to exercise. See table below.
Exercise | 30 min of exercise | 60 min of exercise |
---|---|---|
Exercise Low intensity continuous | 30 min of exercise -25 | 60 min of exercise -50 |
Exercise
Medium intensity continuous |
30 min of exercise -50 | 60 min of exercise -75 |
Exercise High intensity continuous | 30 min of exercise -75 |
60 min of exercise
Not applicable |
Exercise
Resistance, eg. Weight lifting |
30 min of exercise 0 | 60 min of exercise -25-50 |
Exercise
High intensity interval training |
30 min of exercise 0 | 60 min of exercise 0 |
Exercise
Mixed: intermittent aerobic and anaerobic |
30 min of exercise -25 | 60 min of exercise -50 |
Exercise | 30 min of exercise | 60 min of exercise Riddell MC 2017 |
Basal insulin
If you are exercising within two to three hours of having a meal bolus then there is limited benefit from reducing your basal rate before the exercise as well (you may need to do this afterwards).
However, if you are exercising after two to three hours of taking a bolus of insulin or doing prolonged exercise (over 60 minutes) then you may need to set a temporary basal rate reduction as well. See table below.
Exercise ~30 minutes | Exercise ~60 minutes | |
---|---|---|
Aerobic |
Exercise ~30 minutes
50% basal reduction, performed 90 min before exercise or 100% reduction at exercise onset |
Exercise ~60 minutes
50%-80% basal reduction, performed 90 min before exercise or 100% reduction at exercise onset |
Resistance (anaerobic) | Exercise ~30 minutes No reduction |
Exercise ~60 minutes
50% basal reduction, performed 90 min before exercise |
High intensity interval training | Exercise ~30 minutes No reduction | Exercise ~60 minutes No reduction |
Mixed (aerobic and anaerobic) |
Exercise ~30 minutes
100% reduction at exercise onset |
Exercise ~60 minutes
50% basal reduction, performed 90 min before exercise or 100% reduction at exercise onset |
Exercise ~30 minutes | Exercise ~60 minutes Riddell MC 2017 |
Carbohydrate
You may find that you need extra carbohydrate to support your exercise if the insulin alterations are not enough, or you prefer to use this strategy on its own to stop your glucose levels dropping. Usually, exercise under 30 to 45 minutes would not require top up carbohydrate. However, if you find that you need extra carbohydrate then a good starting point would be to aim for 30g carbohydrate per hour, ‘drip fed’ in over the hour (eg. 10g every 20 minutes rather than in one go at the start). Another way of estimating the amount of extra carbohydrate you might need is worked out using your body weight:
For moderate activity: 0.5g/kg body weight/hour of activity
For intense activity: 1g/kg body weight/hour of activity
E.g. Sally weighs 60Kg and is going for a light jog for 60 minutes (she would consider this moderate intensity – for others it may be more intense).
Sally might need 30g carbohydrate over the hour (best taken as 3 smaller 10g snacks over the hour).
It is worth noting that your body is not able to digest more than ~60g glucose per hour. However, your body can take on extra energy from fructose so you may want to try 2:1 glucose:fructose gels/supplements etc if you find you need more than ~60g glucose per hour to fuel the exercise. This may be the case for more extreme endurance type events (lasting several hours) and whether it is fast release carbs (eg. For sessions lasting 45-90 minutes) or slower release carbs (for longer sessions/day events). You may need a combination of both depending on what you are doing. Have a go at experimenting and see what works best for you.
Fast release carbs (shorter session/events) | Carbs (g) | Slower release carbs (longer sessions/day events) | Carbs (g) |
---|---|---|---|
Fast release carbs (shorter session/events) Jelly Babies (4 sweets) | Carbs (g) 20 | Slower release carbs (longer sessions/day events) Raisins (30g) | Carbs (g) 22 |
Fast release carbs (shorter session/events) Dextrose (4 sweets) | Carbs (g) 12 | Slower release carbs (longer sessions/day events) Jaffa cake (each) | Carbs (g) 10 |
Fast release carbs (shorter session/events) Isotonic gel (each) | Carbs (g) 22-25 | Slower release carbs (longer sessions/day events) Fruit bar(each) | Carbs (g) 15 |
Fast release carbs (shorter session/events) Energy sports bar (each) | Carbs (g) 25 | Slower release carbs (longer sessions/day events) Cereal bar(each) | Carbs (g) 22 |
Fast release carbs (shorter session/events) Energy powder drink(500mls) | Carbs (g) 45-50 | Slower release carbs (longer sessions/day events) Malt loaf (1 slice) | Carbs (g) 20 |
Fast release carbs (shorter session/events) Gatorade (250mls) | Carbs (g) 15 | Slower release carbs (longer sessions/day events) Banana (medium) | Carbs (g) 15-20 |
Fast release carbs (shorter session/events) Lucozade original (100mls) | Carbs (g) 8.4 | Slower release carbs (longer sessions/day events) Flapjack (50g) | Carbs (g) 30 |
Fast release carbs (shorter session/events) Lucozade sport (100mls) | Carbs (g) 6.4 | Slower release carbs (longer sessions/day events) Fig roll (each) | Carbs (g) 14 |
Fast release carbs (shorter session/events) Cola (150ml - mini can) | Carbs (g) 15 | Slower release carbs (longer sessions/day events) Oat cake (each) | Carbs (g) 6 |
Fast release carbs (shorter session/events) Apple juice (120ml) | Carbs (g) 15 | Slower release carbs (longer sessions/day events) Bread roll (50g) | Carbs (g) 25 |
Exercise
Recent evidence suggests that it can be possible to stabilise your glucose levels by altering the order in which you do your exercises rather than altering your insulin and/or carbohydrate intake.
For example, if you find that your levels drop quickly after starting aerobic activity (running, walking, cycling etc) then you might choose to do some anaerobic exercise first which will raise your levels to allow a buffer before lowering them with the aerobic exercise. In practice, this could be doing your weights/press ups etc first before going on the treadmill, bike (aerobic workout).
You may still need extra carbohydrate to prevent low blood glucose levels but you could try this strategy and monitor closely to see the effect first.
Similarly, if you have trouble with your levels going high due to interval or weight training for example, then you might start with a longer gentle warm up or factor in some gentle running halfway through your session to try and bring the levels down.
High levels after exercise
This is a common problem people encounter. It can be due to a number of factors, for example over treatment of carbohydrate, your body’s response to the exercise (hormones, lactate) or too much of an insulin reduction. You could try one of the following to manage this situation:
- Additional stretches and warm down period.
- Wait 30 minutes after the above before giving a corrective bolus. In this time drink plenty of sugar free fluids which will rehydrate you and help to bring down the glucose levels.
- Take 50% off the correction the pump suggests.
10 second sprints
This is another tip for trying to prevent hypos from happening during an aerobic activity. It can be applied to most sports in a situation where you want to get a boost of counter regulatory hormones (eg adrenaline) to raise your levels. People have tried this successfully during a long run where they sprint for 10 seconds. Other people have tried this theory by going up a few gears on their bike and sprinting during a long cycle ride or sprinting in the pool for a length when they are swimming. Some people have even done press-ups during a long hike when they were running low on carbohydrates to try to prevent hypos. Remember that even if you manage to protect your levels during the exercise you will need to “pay back” the glucose later on, otherwise you are more likely to hypo due to the additional energy you have expended.
If you find that your glucose levels are above target following a bout of anaerobic exercise or a build-up of lactic acid then one solution to this would be to factor in a longer cool-down period after your main workout. For example, some gentle lengths of the pool after an intensive swim, a gentle jog/walk after a fast run or a low intensity warm down after rugby training.
Refuelling after exercise
Low glucose levels after exercise can happen quite soon after exercise or several hours later. Your body will seek to replenish all the glucose it has used up during the exercise. This is called glycogen replenishment. It is important to support this process so your body stays fuelled up and ready for the next session. Failing to adequately refuel after exercise can increase the risk of further hypos either before or during your next exercise session.
Glycogen replenishment
You have probably heard this term used before when talking about low glucose levels after exercise. Your body has a constant store of glucose (which is called glycogen) in the liver and muscles which are used during exercise. On recovery, your body will seek to replenish these stores of glucose which can lead to low levels either during, shortly after or several hours after exercise.
For some people they find that their glucose levels are stable for several hours after exercise but then suddenly drop. This delay in glycogen replenishment can be addressed if there is a pattern detected of when your levels start to reduce.
It is recommended that you have a small carbohydrate and protein snack directly after exercise in a 3:1 ratio (30g carbs to 10g protein). Whether or not to correct this with some insulin is an individual decision. It might be best to monitor first and see what happens to your glucose levels. A starting point might be 0.5 units insulin and go up from there if necessary. Often people say that they stay high directly after exercise due to the hormones lingering around once they have finished so covering the refuelling snack with a small amount of insulin might be sensible. See below for some refuelling snack ideas:
- Chocolate milkshake (low fat)
- Low fat yoghurt smoothie
- Banana and low fat yoghurt
- Peanut butter/cream cheese on rice cakes/crumpets
- Hummus on toast
It is also important to make sure that you are meeting your overall carbohydrate requirements at your other meals and snacks. Evidence supports basing your larger carbohydrate portion on slow release carbohydrate.
Delayed glycogen replenishment
This can happen several hours after exercise has finished which can cause problems of hypos. It can be a challenge to factor in pump adjustments when the exercise seems a while before and the day has taken over.
Some people find that they need to make a bolus adjustment at the meal after exercise (or even the meal after that) if the glycogen replenishment is delayed.
Using temporary basal rate reductions can also be helpful, for example running a -20-30% reduction over the hours you notice the lower glucose levels following exercise. Remember, exercise in the afternoon/evening can lead to a higher risk of hypos overnight. A suggestion is to set a temporary basal rate reduction of -20% for six hours when going to bed.
The degree of glycogen replenishment will be proportional to the duration and intensity of the exercise. Endurance events (marathons, hikes, long bike rides) may cause lower glucose levels a day or so afterwards until the body’s stores of glycogen are replenished.
Sports nutrition
This is a huge topic and a very active area of research. However, we do know that keeping your body well-nourished is essential for any training plan in order for you to get the training gains you want. There are several schools of thought when it comes to high v’s low carbohydrate diets, ketogenic diets and high protein diets.
Carbohydrate intake
We often get asked in clinic about following a “low carbohydrate” or even a “ketogenic diet”. It can be very confusing when there is so much information available online these days to know what information to trust. Firstly, it’s helpful to know what the definition of a “low carbohydrate diet” is:
Definitions of low carbohydrate diets
Very low Carbohydrate diet (ketogenic): 20-50g per day or <10% of total energy
Low Carbohydrate diet: <50g but, 130g or <10-26% of total energy
Moderate Carbohydrate diet: 130-230g per day or 27-45% of total energy
High Carbohydrate diet (guidelines)
>230g per day or >45% total energy
Why do people follow low carbohydrate diets?
Some people try to restrict the carbohydrate in their diet for several reasons. These reasons might be to control their weight, enable them to use less insulin, fewer hypos related to mealtime bolus insulin, less variability of post meal blood glucose levels.
To date, there is no robust evidence to support these reasons for a low carbohydrate diet apart from requiring less insulin.
As a clinic, we strive to support people in making their own decisions and do not like to dictate to people what they should and should not do. We prefer to take the available evidence at the time and help people understand the pros and cons so that they can make an informed decision. To date, there are several reasons why we do not currently endorse a low carbohydrate diet. These reasons include:
- Little evidence of efficacy.
- No evidence for long term cardiovascular system safety. Remember, a “low carb” diet can also be referred to as a “high fat/protein” diet due to the nature of the foods substituting the carbohydrate. It is of paramount importance that your cholesterol levels are closely monitored if you are following a low carb diet.
- Impairs performance in both endurance and high intensity sports (Arciero PJ J Nutr Metab 2015).
- Risk of Diabetic Ketoacidosis (DKA)due to mild ketotic state. This has been seen in clinical practice due to the lower circulating levels of insulin putting the person at risk of tipping into DKA. This can put you at risk of developing ketones if your carbohydrate intake should suddenly increase (i.e. due to a holiday).
How much carbohydrate should I be consuming?
The advice on how much carbohydrate to consume is calculated on your level of training and your body weight. Remember, not giving your liver and muscles enough glucose through your daily diet can lead to fatigue, lack of training gains and increased hypoglycaemia both during and after training.
Training Load |
Carbohydrate Recommendations |
---|---|
Training Load
Very light training (low intensity exercise or skill-based exercise) |
Carbohydrate Recommendations 3-5g/kg body weight/day |
Training Load
Moderate intensity exercise for 1hr/day |
Carbohydrate Recommendations 5-7g/kg body weight/day |
Training Load
Moderate to high intensity exercise for 1-3 hrs/day |
Carbohydrate Recommendations 6-10g/kg body weight/day |
Training Load
Moderate to high intensity exercise for 4-5 hrs/day |
Carbohydrate Recommendations 8-12g/kg body weight/day |
Training Load |
Carbohydrate Recommendations Burke, L.M., (2010) |
Protein intake
Protein is needed in the body for growth and repair. Protein also helps the body refuel with glucose after a workout which is why the advice is to have a small amount of protein with any post exercise refuelling snack (see examples above). Lots of people ask how much protein they can or should consume because they want to increase their muscle mass. Below are some guides to help you decide a safe limit of protein to consume to support your training.
Your kidneys are responsible for processing and excreting protein in the diet so consuming too much may put additional pressure on them. You may like to speak to your doctor if you are unsure if you have any kidney impairment which would affect your safe limit of protein.
Training type and load | Protein recommendations |
---|---|
Training type and load
Sedentary men and women |
Protein recommendations
0.8-1.0g/kg body weight/day |
Training type and load Endurance athletes |
Protein recommendations
0.8-1.2g/kg body weight/day |
Training type and load
Resistance (strength) athletes |
Protein recommendations
1.0-1.7g/kg body weight/day |
Before buying expensive supplements it might be worth keeping a food diary to assess how much protein you are getting in your normal diet and whether or not you can optimise this first. To do this you could keep a diary on a simple food diary app on your phone or use the basic list below to calculate your protein intake. Food labels will also be a useful guide.
Food | Amount | Protein Content (g) |
---|---|---|
Food Chicken breast (grilled) | Amount 130g | Protein Content (g) 37 |
Food Minced beef | Amount 250g | Protein Content (g) 52 |
Food Beef steak | Amount 8oz | Protein Content (g) 45(!) |
Food Beef burger | Amount 1 burger | Protein Content (g) 10 |
Food Pork chop | Amount 1 chop | Protein Content (g) 30 |
Food Ham (average slice) | Amount 1 slice | Protein Content (g) 4 |
Food Bacon | Amount 1 rasher | Protein Content (g) 5 |
Food Sausage | Amount 1 sausage | Protein Content (g) 3 |
Food Lamb chop | Amount 1 chop | Protein Content (g) 20 |
Food Tinned tuna | Amount 1 small tin | Protein Content (g) 30 |
Food Salmon fillet | Amount 140g | Protein Content (g) 27 |
Food Tinned salmon | Amount 1 small tin | Protein Content (g) 35 |
Food Tinned sardines | Amount 1 small can | Protein Content (g) 16 |
Food Cod in breadcrumbs | Amount 125g | Protein Content (g) 16 |
Food Fish finger | Amount 1 finger | Protein Content (g) 4 |
Food Soya burger | Amount 1 | Protein Content (g) 6 |
Food Chickpeas/kidney beans | Amount 1 tin (400g) | Protein Content (g) 17 |
Food Baked beans | Amount 150g | Protein Content (g) 8 |
Food Cottage cheese | Amount 150 | Protein Content (g) 15 |
Food Cheddar cheese | Amount 50 | Protein Content (g) 12 |
Food Milk | Amount 200ml | Protein Content (g) 7 |
Food Yoghurt low calorie | Amount 150g pot | Protein Content (g) 7 |
Food Rice pudding | Amount 200g | Protein Content (g) 7 |
Food Egg | Amount 1 egg | Protein Content (g) 8 |
Food Porridge (made with milk) | Amount 160g | Protein Content (g) 5 |
Food Peanuts | Amount 25g (handful) | Protein Content (g) 6 |
Food Pizza | Amount 250g | Protein Content (g) 26 |
Food Ice cream | Amount 1 scoop | Protein Content (g) 2 |
Food Digestive biscuit | Amount 1 biscuit | Protein Content (g) 1 |
If it becomes obvious to you that you are not consuming enough protein to meet your daily requirements then you may decide to look at a supplement to meet (but not to exceed) them.
Further reading
Hopefully this information booklet has provided you with some ideas, information and advice around managing exercise with your insulin pump. For more general reading around diabetes and managing exercise then you may find the below references useful:
Books
- 'Type 1 Diabetes – Clinical Management of the Athlete' by Ian Gallen
- 'Getting Pumped! A Diabetes and Exercise Guide for Active Individuals with Type 1 Diabetes' by Michael Riddell
Websites
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