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How does exercise affect blood sugar levels?

How does exercise affect blood sugar levels?

Exercise is beneficial for absolutely everyone but for people with type 2 diabetes, its impact on blood sugar levels makes it one of the most effective ways to manage the condition.
Beth Plumptre
3/12/21
10
min read
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Quick summary

  • Regular exercise is one the most important things you can do if you have type 2 diabetes because it can help regulate blood sugar levels.
  • During exercise, the working muscles take glucose from the blood for energy, lowering blood sugar levels and increasing insulin sensitivity.
  • The effect of exercise on insulin sensitivity can last for up to 48 hours after the activity.
  • Some type 2 diabetes medications work to lower blood sugar and when taken in conjunction with intense exercise can cause a ‘hypo’, so it's important to get medical advice before starting a new routine if you’re on these medications. 
  • Simple everyday activities like taking the stairs, getting off the bus a stop earlier, cleaning the house, or walking after dinner can all have a positive effect on blood sugar levels.

Sitting right alongside dietary changes and lifestyle adjustments such as giving up smoking, taking up regular exercise is one of the most important changes you can make following a type 2 diabetes diagnosis—or even if you’ve been diagnosed with diabetes for a while.

Among the countless benefits of engaging in routine physical activity, regular exercise can decrease food cravings, maintain weight loss, and even protect against mental health conditions like Alzheimer’s and dementia.

However, one of the best advantages of exercise for people with type 2 diabetes is its ability to affect blood sugar levels.

Exercise can lower blood sugar levels

Physical activity increases insulin sensitivity

When the body can’t use insulin properly, key areas in the body like the liver, muscle, and body fat find it difficult to absorb glucose for energy. This is known as low insulin sensitivity or insulin resistance—a state that can lead to health complications such as type 2 diabetes.[1] 

Enter, exercise. By engaging in as little as 30 minutes of aerobic activity a day (exercise that gets the heart pumping), insulin sensitivity and blood sugar control can improve, and in one study it was found that these effects last for up to 48 hours after the activity.[2,3] This means that your muscle cells find it easier to use any available insulin to take up glucose from the blood during or after the activity. 

Exercise can improve insulin sensitivity for up to 48 hours after the activity

Sylow et al, Nature Reviews Endocrinology

Part of this is due to a clever protein called GLUT4. During exercise, your muscles need fuel to work hard and GLUT4 allows glucose to be taken from the blood and enter the muscles, providing that much-needed energy. When we’re at rest GLUT4 usually sits inside the cells, not really doing a huge amount. As soon as we start exercising it jumps into action and moves outside the cell to help it take in glucose from the blood. GLUT4 then stays in this outside position for hours after exercise, continuing to help glucose enter the cell, which is why exercise has a lasting effect on blood sugar levels.[4,5]

As if that isn’t motivation enough to start moving, research has now shown that if people with type 2 diabetes continue to exercise, the amount of GLUT4 increases, which helps control blood sugar glucose levels and increase the body’s sensitivity to insulin![6]

There’s also evidence that intense exercise, such as running and swimming, causes a 20-fold increase in blood flow around the muscles during the activity.[7] This means that as more blood arrives to the muscles, it brings more glucose with it, which in turn is taken up by the muscle.

Exercise can lead to weight loss

There’s no doubt that exercise contributes to weight loss but in addition to the visible physical benefits is its ability to reduce body fat.

By body fat, we don’t just mean the visible fat under the skin but the fat inside the body, too. Regular exercise can reduce the amount of fat in the liver and pancreas, which is a big plus as we now know that it’s this internal fat that stops these organs from being able to regulate blood sugar. Reduce the internal fat deposits, and the liver and pancreas can regain their natural control of blood sugar levels.

Exercise can (temporarily) increase blood sugar levels

When it comes to blood sugar levels, exercise is widely accepted to be a good idea and can even improve glucose tolerance and insulin sensitivity for up to 48 hours after the activity.[3]

However, while exercise has its perks for managing blood sugar levels, it’s worth bearing in mind that some types of exercise, particularly vigorous or intense workouts, can lead to temporary glucose spikes. You may have noticed this if you measure your blood sugar levels regularly, either by finger prick or with a continuous glucose monitor.

This is because exercise boosts the body’s production of adrenaline—a stress hormone produced at serious moments when your flight or fight response kicks in. Adrenaline increases the level of glucose in the blood, providing an energy boost to carry out a flight or fight response—or in the case of a gym session, to carry out those weight repetitions or laps in the pool.[8] 

Before swearing off exercise forever, it’s important to note that this blood sugar increase is only a temporary effect. Daily movement is really important not just for blood sugar levels but for your entire body. Official guidelines suggest aiming for 150 minutes of exercise a week but rather than clock-watch, try adding bursts of movement into your day whenever you can.[4]

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How to manage blood sugar levels while exercising on medication

Power-walking, high intensity workouts, swimming—whatever you decide to do to get your body moving, it’s important to be mindful of your medications (if you’re on them).

Type 2 diabetes medications, such as insulin, sulfonylureas, and meglitinides, work to lower blood sugar levels and can cause a dangerous ‘hypo’ (hypoglycemia—very low blood glucose) when taken in conjunction with intense exercise. This can cause dizziness, sweating, and other symptoms of low blood glucose. 

Before deciding on an exercise routine, it’s important to first check in with your health professional for advice. Depending on your medications and your personal glucose response, lower doses of your medications might be necessary to keep your glucose levels safe.

Simple exercises to manage blood sugar levels

Starting a fitness routine might feel daunting but even with everyday activities, you can start making healthy changes to your lifestyle. Here are some simple exercise habits that you could easily include into your daily routine.

🚌. Get off the bus early

Try getting off the bus or train a stop or two early and walk the remainder of the way. As well as getting in your steps, it’s a chance to explore a new area—you may even find your new favourite coffee spot! Walking is very good for you, physically and mentally, and doing just a little bit more each day can be really effective.

💪 Take the stairs

Wherever you can, take the stairs instead of the lift or escalator. It will help build your physical fitness (hello, quads!) and the more you do it, the faster you’ll get. It’s also good for keeping your joints healthy and strong.

🚶‍♀️Walk after dinner

Going for a walk after dinner, even just 15 minutes round the block, can significantly improve your blood sugar levels after eating—and up your step count! It can also help reduce the time it takes for food to move from the stomach to the small intestine, making you feel fuller for longer (and maybe helping you resist an evening snack). 

🧹 Clean the house

Not the most glamorous suggestion we know, but just 30 minutes of cleaning can burn up to 100kcal. Exercise and a clean house—that’s a win, surely.

🕺 Dance (like nobody’s watching)

Dancing is a fail-safe mood-booster and is really good exercise. Try listening to some of your favourite songs and dance along in the morning for an instant happiness-hit.

If you monitor your blood sugar levels, guidelines suggest starting to exercise only if your blood glucose levels fall within 90 and 250 mg/dL (5.0 and 13.9 mmol/L).[9] But remember, these are only guidelines—everyone is different so be sure to speak to your doctor before making any major changes.

How to manage your blood sugar levels while exercising

We’ll close with a few tips on how to manage your blood sugar levels safely while exercising. It’s important to note that everyone will respond differently to exercise and that the intensity, duration, and even type of exercise will affect your blood sugar differently. If you’re ever worried, always consult your medical team. 

  • Try to exercise regularly to maintain the benefits of increased insulin sensitivity
  • Stay hydrated to keep your blood sugar levels down
  • Work out the whole body by doing different types of exercises
  • Have a snack handy in case you start feeling lightheaded or experiencing other symptoms of hypoglycaemia during intense exercise
  • If you do monitor your blood sugar levels, it’s worth keeping an eye on them before, during, and after exercise to see how your body responds to movement
  • If you have one, keep your medical ID on you
  • Stop exercising if you have a very rapid or irregular heartbeat

References

[1] Freeman A.M., Pennings N. (2021) Insulin Resistance. StatPearls [Internet]. Accessible here.

[2] Bird, S.R., Hawley, J.A. (2017). Update on the effects of physical activity on insulin sensitivity in humans. BMJ Open Sport Exerc Med 2:e000143. Available here.

[3] Sylow, L., Kleinert, M., Richter, E.A., Jensen, T.E. (2017). Exercise-stimulated glucose uptake — regulation and implications for glycaemic control. Nat Rev Endocrinol 13:133-148. Available here.

[4] Colberg S.R., Sigal R.J., Fernhall B., et al. (2010). Exercise and type 2 diabetes: the American College of Sports Medicine and the American Diabetes Association: joint position statement. Diabetes Care 33(12):e147-e167. Accessible here.

[5] Richter, E.A., Hargreaves, M. (2013). Exercise, GLUT4, and skeletal muscle glucose uptake. Physiol Rev 93(3):993-1017. Accessible here.

[6] Daugaard, J.R., Nielsen, J.N., Kristiansen, S., et al. (2000). Fiber type-specific expression of GLUT4 in human skeletal muscle: influence of exercise training. Diabetes 49(7):1092-5. Accessible here.

[7] Rose A.J., Richter E.A. (2005). Skeletal muscle glucose uptake during exercise: how is it regulated?Physiology (Bethesda) 20:260-270. Accessible here.

[8] Verberne A.J., Korim W.S., Sabetghadam A., Llewellyn-Smith I.J. (2016). Adrenaline: insights into its metabolic roles in hypoglycaemia and diabetes. Br J Pharmacol 173(9):1425-1437. Accessible here.

[9] Colberg S., Sigal R., Yardley J., et al. (2016). Physical Activity/Exercise and Diabetes: A Position Statement of the American Diabetes Association. Diabetes Care 39(11):2065-2079. Accessible here.

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