Exercise and Diabetes:
Why Exercise?
Physical activity is extremely important as part of a healthy lifestyle. It:
- Helps you feel good about yourself (afterwards, if not during)
- Improves your sensitivity to insulin and helps improve blood glucose levels
- Improves the fitness of your heart and circulation and so reduces the risk of heart disease and stroke
- Helps you to control weight
- Can improve the proportions of the good and bad types of cholesterol
- Helps you to lose fat and gain muscle — this helps to improve strength, mobility and flexibility
- Can help reduce blood pressure
- Can reduce stress
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How much exercise and what type?
It is important to take in to account your type of diabetes and take some precautions when planning your program of exercise.
It is considered that 15-30 minutes of aerobic exercise a day is adequate. Aerobic exercise helps you breathe deep and benefits the heart. Examples of aerobic exercise include swimming, walking, jogging, cycling and dancing. Discuss the various types of exercise with your doctor/diabetes nurse and seek advice on any special precautions. For example if you have problems with the nerves of your feet your may be advised to choose a form of exercise which does not place any stress on your feet.
When you start an exercise program, go slowly. Then gradually increase the intensity and length of your sessions. Talk to your doctor/nurse for specific advice.
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What precautions should I take?
Type 1 diabetes:
Test your blood sugar before exercising. If your levels are less than 5.5 mmol/l have a snack before exercising. If your sugar levels are between 5.5 to 8.5 mmol/l, have a snack handy to take during exercise. If you plan on taking vigorous exercise and you feel you are likely to have a hypo consider the option of cutting your dose of insulin by a few units. Discuss this with your doctor or diabetes nurse.
Type 2 diabetes:
Carry some glucose tablets or a sweet drink to use in an emergency
Examine your feet before and after exercise - look for signs of redness or blistering.
Drink plenty of fluid before, during and after exercise. When exercising, your body loses more fluid to keep you cool. By the time you feel thirsty, you may already be getting dehydrated. Dehydration (not enough fluid in your body) can affect your blood sugar level.
Look out for symptoms of hypoglycaemia. The usual symptoms of increase in heart rate and sweating may also occur due to exercise and should not be ignored. If in doubt check your blood sugar.
No matter what kind of exercise you do, you should warm up before you start and cool down when you're done. To warm up, spend 5 to 10 minutes doing a low-intensity exercise such as walking. Then gently stretch for another 5 to 10 minutes. Repeat these steps after exercising to cool down.
If you have circulatory problems or neuropathy your feet may develop blisters or ulcers. Ensure that you wear appropriate foot wear that are well fitted. Check your feet following exercise to identify problems early.
As a general rule avoid exercising if your blood sugar is too low or too high.
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Hypoglycaemia (hypos):
The main reasons for hypos during and after physical activity are that your muscles use up the glucose in your blood for energy and although your body will start to release stores of glucose from your liver it may not be enough. As a result your blood glucose level may drop too low. Once you have stopped exercising your body will need to replace the stores of glucose it may have used up and will also need extra glucose for your muscles to recover. This means there is still a risk of your blood glucose levels dropping too low even for some time after you’ve stopped doing your activity.
A hypo may also be caused by an increased rate of absorption of insulin from injection sites giving higher levels of circulation more quickly. A hypo can be prevented by:
- reducing insulin
This is only possible if the activity is planned. Although your doctor or diabetes specialist nurse can suggest a certain reduction in your insulin dose, it is really a matter of trial and error to see what suits you for different types of physical activity (intense and duration), at different times of the day when you have more or less insulin circulating
- increasing carbohydrate
If you are exercising shortly after a meal the best thing to do is to have extra starchy carbohydrate - such as bread, pasta, rice, cereals and potatoes - at your meal. If you are unable to eat more at that meal because it would make you feel full then you will probably need to take a snack beforehand — like a cereal bar, small chocolate bar, ice cream, biscuits or a cake bar. You should also take a snack like this if it has been 1-2 hours since your last meal.
If you are doing strenuous exercise (for example football or squash) you will probably need a top up of glucose during the game. As you will be thirsty anyway it is usually convenient to take this top up as a glucose drink, sport drink or fruit juice. If you are exercising for a long period of time — for example, a cycle ride or long walk — you will need to take food and drinks, and snack regularly. Suitable snacks would be cereal bars, sandwiches, fruit juice, biscuits, currant buns as well as supplies of faster acting carbohydrate like Lucozade or glucose sweets.
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Checklist for exercise:
- Talk to your doctor about the right exercise for you.
- Check your blood sugar level before and after exercising.
- Check your feet for blisters or sores before and after exercising.
- Wear the proper shoes and socks.
Drink plenty of fluid before, during and after exercising.
- Warm up before exercising and cool down afterward.
- Have a snack handy in case your blood sugar level drops.