Exercise is a key factor for management of type 2 diabetes and delaying the development of associated moralities Exercise is known to have great benefits for blood glucose control as well as for weight loss. Only 39% of adults with T2DM are physically active, compared to 58% of unaffected Americans, showing that many who suffer are not taking advantage of the health benefits that physical activity can bring.
What happens to blood glucose and insulin during exercise?
When we eat carbohydrate based foods, insulin is released from the pancreas and stimulates the muscle and liver cells to take up the extra glucose from the blood, thus keeping blood sugar levels at a stable level. In anaerobic (short bursts) of exercise, the liver releases glucose to fuel the body, however in moderate intensity exercise, muscles take up a lot more glucose to enable them to carry out the activity. When this occurs, insulin production may decrease so that hypoglycaemia is prevented.
However, in the case of very intense physical activity, it is possible that there will be an increase in blood glucose, particularly in people with diabetes. This is due to stress hormones being realised which causes the body to increase available blood sugar in order to provide fuel for muscles.
Although exercise is generally beneficial for blood glucose control, an exercise program should be discussed with a doctor and blood sugar should be closely monitored during exercise in case this happens.
Benefits of Exercise for those with type 2 diabetes mellitus.
Increased Blood Glucose Uptake
Both resistance and aerobic exercise can increase the uptake of blood glucose into skeletal muscle cells. This means that blood glucose levels are kept at a lower level despite lower insulin levels or insulin resistance present in type 2 diabetes. Resistance exercise may also result in lower fasting blood glucose levels for up to 24 hours after the physical activity.
Short term decreased insulin resistance
Aerobic activity has been shown to increase the action of insulin in those with type 2 diabetes. Most individuals will see an improvement in their blood glucose levels for 2 to 72 hours after exercising and it seems that longer duration or more intense physical activity causes enhanced insulin action for longer periods.
Increased Whole Body Insulin Action
Both resistance and aerobic exercise are associated with an overall improvement of insulin function as well as blood glucose control, fat oxidation and storage in muscle. Exercise can enhance the responsiveness of muscle to insulin, thus reducing resistance.
Burning body fat
Exercise burns calories, which in combination with an appropriate diet, can lead to weight loss. Weight loss has been to shown to be a key factor in increasing insulin sensitivity, with some individuals even managing to reverse T2DM by losing weight when in the early stages.
Aside from the direct benefits for T2DM, there are numerous other health benefits of exercise. These may also play a part in reducing the risk of other co morbidities which those with T2DM may be more susceptible to such as cardiovascular disease.
Physical activity can improve health by increasing strength and mobility, possibly lowering blood pressure and levels of ‘bad’ LDL cholesterol, improving circulation and increasing bone density. It can also have a positive effect on energy levels, stress reduction and releasing tension.
Precautions to follow when exercising
There is always the chance that exercising with T2DM will result in hypoglycaemia or low blood sugar levels. This is more of a concern for those taking insulin or other medications and can be avoided by taking medicines at the same time each day, eating carbohydrate based foods at regular intervals and testing blood sugar levels before, during and after exercise in order to increase awareness of exactly what is happening, particularly if you are just starting out.
In cases of hyperglycaemia, exercise should not be attempted until glucose levels are back under control. Although there is a possibility the exercise will lower levels, it is also possible that it will increase them which could be dangerous.
It is advisable to take a few precautions, especially when new to exercising such as carrying a carbohydrate based snack that is quickly absorbed such as juice, exercising with a friend and wearing a medic alert bracelet.
If you intend on taking part in long or particularly strenuous exercise, you should talk to your doctor about appropriate medication changes as hormones released in this type of exercise can counteract the effects of insulin and may result in hyperglycaemia.
For those with secondary conditions caused by diabetes such as eye problems or nerve damage, exercise may not be suitable. Options should be discussed with a health care professional to find what is suitable for you.
What types of exercise and how much?
Those with type 2 diabetes contemplating starting an exercise program should first consult with their doctor as to if this is appropriate for them, if any changes will need to be made to medications and also how much exercise is appropriate to start with.
An exercise physiologist or trainer may also be useful in developing a personalized program, as well as motivating and supervising the individual in the first stages. When choosing the type of exercise, try to find something enjoyable and easy to do so that you are more likely to stick to it.
It is recommended that moderate intensity aerobic activity, (the type that raises you heart rate), should be undertaken at least three times a week for a minimum total of 150 minutes in bouts of at least 10 minutes, although more than this may result in greater improvements.
More vigorous activity may also have greater benefits, however should be supervised and worked up to gradually. There should be no more than two consecutive days between sessions as this is thought to undo or slow the improvements seen in insulin action.
Resistance training is also important for those with type 2 diabetes and could include activities such as weight, resistance bands and body weight strengthening activities. Ideally this should be undertaken at least twice or three times per week on non-consecutive days. It is thought that greater resistance, i.e. heavier weights are more effective in terms of blood glucose control, however it is important to work up to this slowly to avoid injury.
Each training session should involve five to ten exercises that target all the key areas of the body. It is worthwhile spending time with a personal trainer to learn how to do the exercises correctly and how to build your program to get the best results.
It is also advised that those with type 2 diabetes try to increase their levels of incidental exercise. This could be as simple as walking or cycling instead of taking the car, using the stairs instead of the lift or playing with the children.
References used in this article