Diabetes. A world of possibilities coverThis is the second part of chapter 5 of my book “DIABETES. A world of possibilities”, which I’m publishing here for free. You can access all the chapters published until now here.

…For example, I found that when I ate half an apple before exercise (always depending on how high the sugar was before the activity), my blood sugar afterwards was high. I tested something different: instead of an apple, I ate half a slice of bread or half a cracker with peanut butter without sugar and a bit of cheese, and afterwards, glucose was fine.
Glucose also varies if I go to run or if I exercise at home with a cross-trainer (stationary bike type machine but where you stand, you move the arms, legs and the entire body)

And sometimes, doing exactly the same activity and eating the same as other days when glucose was fine, blood glucose was high. As you see, and you probably know from experience, this is not an exact science in which you do A and you always get B. But we must do all that we can to learn from our body and get closer to that.

Reading comments from other type 1 diabetics with the same problem when exercising, I learned that for some people, sports raise their blood glucose instead of lowering it. It seems that some bodies with type 1 perceive sport, especially if anaerobic, as a stressful situation, thus activating the sympathetic nervous system, which in turn activates the “fight or flight” response. The sympathetic nervous system helps us to meet emergency needs, such as the struggle for survival or finishing a race or vigorous play. A vigorous exercise requires a high energy supply, and the sympathetic nervous system helps by activating the endocrine organs, such as the adrenal glands.

The adrenal glands release the stress hormones adrenaline and noradrenaline in the blood, which in turn stimulates the liver to release glucose at a faster rate than normal. When this rate exceeds the rate at which glucose is absorbed by the active muscle tissue, blood glucose rises.

Some studies place the exercise intensity threshold at or above 80% of a person’s ability for maximal exercise. That is, if you have trouble breathing and you can not have a conversation with someone while doing the exercise, that means you are doing more than 80% and glucose might rise (if your body reacts like mine).

When I learned about this seemingly contradictory effect, I decided to do a test. One day, when I exercised at home, I tested glucose every 15 minutes during exercise without having eaten anything before. And indeed, I saw my glucose was rising instead of dropping. I repeated the experiment the next day to be sure that it was not just that day. Same results.

While on one hand it bothered me to know that I would need insulin even to exercise, I did not want to stop exercising. So I started to inject 1 unit of ultra-fast insulin just before exercise and, since then, I have perfect glucose levels before and after exercise. Although I have to inject 1 unit of insulin, it is a relief to see that my BG is fine. I even need less insulin at the next meal because the muscles are still burning energy and insulin did its job.

Therefore, if you saw that glucose rose during exercise and you were “scratching your head” to know why, now you have something to test.

If you are a parent of a kid with type 1 diabetes performing sports activities, it would be wise to check if blood sugar rises or drops while exercising, and act accordingly: Eat something before if it drops or inject insulin if it rises (it’s better if you consult with your doctor on this). And keep in mind the type of sport s/he is practising, whether it is aerobic/relaxed or anaerobic/vigorous, as the body’s response to each type of sport may be different.

Also, something to consider is the time of day at which to exercise. Dr. Richard K. Bernstein says in his latest book that exercising in the morning when you get up can raise blood glucose even more. This is due to a phenomenon called “dawn phenomenon.” Some diabetics experience high blood sugar levels when they wake up in the morning. It is believed that, between 2:00 and 8:00 in the morning, there is an increase of the growth hormones, cortisol, glucagon, and epinephrine, increasing insulin resistance, with the effect of increasing blood glucose.

According to Dr. Bernstein, some of his patients with type 1 diabetes who prefer to exercise in the morning need to inject insulin before the activity to cover that sugar rush caused by the dawn phenomenon.

Exercises for diabetics

So far, I have talked about the benefits of walking, especially to show those who do not practice much physical activity that it is very easy to get much better health just by taking a walk.

But many other people do not like walking or prefer sports or any other more vigorous exercise.

At this point, the opinions of the experts vary greatly. Some recommend aerobic exercise, and explain why anaerobic exercises are even harmful, especially to people with diabetes. Others recommend more anaerobic exercises.

Let’s consider these two points of view.

I will define first in a simple way what aerobic and anaerobic exercises are, so that everyone knows what I mean in each case.

Aerobic exercise: gentle exercise where the muscles are not deprived of oxygen (usually you can talk while doing the activity because you can breathe normally.)

Anaerobic exercise: intense exercise where the muscles are deprived of oxygen during the activity (you can not talk during the activity, since you have a lack of air.)

Aerobic exercise advocates argue that the lack of oxygen in anaerobic activities leads to increased acidity and sugar levels in the blood and, therefore, stress the pancreas. Without enough oxygen, the body switches to self-preservation, producing cholesterol and keeping fat to neutralize the acids. Thus, the body burns sugar instead of fat for energy.

According to this theory, the most recommended types of aerobic exercises for diabetes are: walking, jogging, swimming, cross-trainer machines, trampoline, yoga, or pilates and some types of exercises with weights/dumbbells.

Advocates of anaerobic exercises argue that, when muscles are aerobically exercised, they do not increase mass greatly and require less glucose for energy needs. On the other hand, anaerobic exercise requires 19 times more glucose. Thus, the lowering of blood glucose during and after continuous anaerobic activity is much higher than after the same time performing an aerobic activity.

As the body gets used to these intensities, it will adapt to this level of stress and transport glucose more efficiently into muscle cells. As the strength and muscle mass develops, glucose transporters in cells will increase significantly in size. As a result, the efficiency of insulin (natural or injected) to transport glucose, and to remove the supply of glucose by the liver, increases considerably.

This way, in a short time, an increased sensitivity to insulin to lower blood sugar levels develops the same way as a decrease in insulin requirements (natural or injected). The general drop of insulin in the blood reduces the body’s ability to hold on to stored fat, thereby decreasing insulin resistance. (4)

Types of anaerobic exercises: weight lifting, crunches, pushups, running uphill, uphill cycling, etc., always performed with appropriate weights and enough speed to experience some pain. It is recommended to learn how to do weight-lifting correctly, for instance, attending a gym 1 or 2 times to learn it (or look for a video online where it is well explained). Then you can keep exercising at home if you prefer. If done wrong, you could hurt a muscle or bone.

As you can see, there are theories for all tastes and both are logical.

In the end, what counts is that everyone practice the exercise that feels better for them, that they look forward to, and that they are motivated to continue doing regularly. Checking glucose levels before and after exercising (especially with type 1 diabetes) will help us better control blood sugar levels and find the right activity, adequate duration and intensity, and carbohydrate intake.

Whatever exercise or sport you decide to do, try to progress slowly over time. Even walking can become a progressively muscle strengthening activity, adding some weight on the arms when you walk, or walking farther or faster. Gradually, you will find that you feel more and more comfortable and see that it is easier and easier to exercise. Enjoy this state for a while and then slightly increase the distance or speed or weight, etc.

Imagine how well you will feel and how good you will look after some time exercising. You will also feel healthier and younger.

(4) Bernstein, R. K. (2011) Dr. Bernstein’s Diabetes Solution. The complete guide to achieving normal blood sugars, New York: Little, Brown and Company, 4. edición, p. 228.

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1 Comment on Chapter 5 (Part II) – Exercise.10,000 steps away from your health

  1. […] That’s something that has been bothering me a lot lately: I go to play sports, even with BG in normal ranges, and return with high BG (hyperglycemia). You lose the motivation to keep exercising! I think this is not usually the case with type 2 diabetes. But with type 1, there are more things to consider. You have to do a lot of trial/error to learn how your body works and how exercise affects it, food and insulin [continue here…] […]