Physical activity for type 1 diabetes

Physical activity is important for health and well being, whether you have diabetes or not.

The many benefits of exercise include helping to maintain or lose weight, reduce cholesterol and blood pressure, reduce stress and tension, improve mood, sleep and mental activity and achieve target blood glucose levels.

When you have type 1 diabetes, exercise can affect blood glucose levels in a number of ways.

The factors that someone with type 1 diabetes needs to consider are:

1. Hypoglycaemia (low blood glucose) is more likely to occur with exercise because:

  • The blood stream, liver and muscles ‘burn up’ glucose to release energy
  • The cells of the muscles become more sensitive to insulin for up to 12-16 hours after exercise, particularly after very intense exercise and or prolonged exercise. Some people may hypo during or immediately after exercise or can even hypo many hours later, overnight or the next morning
  • Muscles that are exercised can continue to take up glucose without insulin
  • Extra glucose is moved from the bloodstream to replace liver and muscle stores

2.  Hyperglycaemia (high blood glucose) can occur:

  • After brief, very intense exercise such as competitive sports, there is an increase in the level of the hormone adrenaline.  Adrenaline  stimulates the release of glucose from the liver. Blood glucose may later fall.
  • When blood glucose levels are high (15mmol/L) the body may start producing ketones, indicating that there is not enough insulin in the body.  In this situation, exercise will not help to reduce glucose levels, but rather may cause them to increase further. Usually, extra insulin is needed.

How to avoid hypoglycaemia?

Understanding how your body responds to exercise is important and monitoring your blood glucose before, during and after exercise can give you that information.

Factors such as the duration and intensity of your exercise and your current blood glucose level can help you work out how much extra carbohydrate to eat and if you need to reduce your insulin dose.

Tips on how to avoid hypoglycaemia during exercise

  • You may need to reduce your insulin dose before or after exercise or at bedtime. Speak to your doctor or diabetes educator about how to do this safely
  • Check your blood glucose before, during and after exercise
  • Carry glucose such as jelly beans or Lucozade or sports drink to treat a hypo
  • Make sure your BGL is above 6mmol/L before starting exercise
  • Avoid injecting into the arms or legs as your insulin may work more quickly and increase the risk of a hypo The rate of absorption is more consistent when injecting into the abdomen or buttocks
  • Replenish your liver glucose stores by eating extra carbohydrates after exercising
  • Prevent delayed hypoglycaemia overnight or on waking by having a carbohydrate snack before bed

Dos and don’ts of exercise

  • Never completely omit insulin or hyperglycaemia and ketones could develop. If your blood glucose is high (over 15 mmol/L) and ketones are present or blood glucose is over 20 mmol/L do not exercise. Take extra insulin and delay exercise (refer to sick day action plan)
  • If you have diabetes complications you need to take some precautions as your ability to tolerate exercise may be reduced or some complications could be worsened by some types of exercise. Speak to your doctor about any exercise you should avoid or modify. For example, avoid straining and jarring exercises if you have retinopathy.
  • If you have had type 1 diabetes for 15 years or more, are aged over 35, have risk factors for heart disease, or have diabetes complications, you should have a check up with your doctor before starting any new exercise. This should include ECG, blood pressure, feet, kidney, eye checks, autonomic nerve function. These checks are also part of your annual diabetes check.
  • Warm up and cool down
  • Wear well fitting sports shoes, that have adequate shock absorption
  • Drink plenty of fluid to keep hydrated

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