Can exercise prevent type 2 diabetes?
Exercise is a great tool for preventing type 2 diabetes. Studies have shown that even small changes in peoples’ physical activity levels can lead to decreased rates of type 2 diabetes, so every movement matters.
In a study of the Diabetes Prevention Program – a Center for Disease Control and Prevention lifestyle change program that enrolls people who are at high risk of developing diabetes – participants who achieved 150 minutes of moderate intensity activity per week had a 44% reduction in diabetes development.
What is one main obstacle to exercise for both patients with type 1 and type 2 diabetes? How can those obstacles be overcome?
One major obstacle to exercise can be exercise-induced hypoglycemia, or low blood sugar. This is a common challenge for people with type 1 diabetes and for people with type 2 diabetes who are on certain glucose-lowering medications such as insulin. Different exercises can affect blood sugars differently, and these effects are not only experienced for the duration of the activity or what we call the “bout” of exercise, but also for up to 48 hours afterward in what we call the “post-bout” period.
One area of interest in exercise and diabetes research is to evaluate whether the specific order of performing exercises – such as resistance exercise followed by aerobic exercise – can help decrease low blood sugars. It is important that people living with diabetes discuss their exercise regimens with their diabetes providers as we have many individualized strategies to help prevent these low blood sugars and support each person’s exercise journey.
What are the benefits?
Many benefits are associated with regular exercise for people living with diabetes or who are at risk for diabetes. Some of these benefits are a reduction in blood pressure, an improvement in insulin sensitivity and glucose levels, prevention and minimization of weight gain, improvement in cholesterol levels and a reduction in rates of death from cardiovascular disease. This last benefit is particularly important because people with diabetes have a higher risk of bad outcomes from cardiovascular disease. We know that if we help people to improve their cardiorespiratory fitness (ability to exercise) we can decrease mortality.
Are there any dangers around exercise for those with diabetes?
Consistent exercise is associated with a reduction in cardiovascular risk. However, sudden exercise can be a cardiovascular stressor and, in susceptible individuals, may be associated with cardiovascular events. If someone with diabetes is just starting out on their exercise journey, it may be a safer and more effective strategy to start with being consistent with a low-intensity exercise and work up to higher intensity rather than being more sporadic with a high-intensity exercise.
Additionally, people with diabetes can have decreased sensation and blood flow to their feet, which puts them at higher risk for trauma to their feet from weight-bearing exercises. These are both important reasons for people with diabetes to discuss exercise programs with their providers so that they can assess their individual risks and help safely support their exercise.
What types of exercise – and their frequency – have been shown to be beneficial?
Both aerobic (running, jogging, brisk walking, swimming, cycling) and resistance (weights, resistance bands, body weight exercises) exercise regimens have been shown to help prevent type 2 diabetes and improve outcomes in people with diabetes.
An optimal modality and frequency of exercise have not been established, but the American Diabetes Association recommends that most adults with type 1 or type 2 diabetes engage in at least 150 minutes of moderate-to-vigorous-intensity aerobic activity and two to three sessions of resistance exercise per week.
The intensity of an aerobic activity can be defined by the amount of oxygen used by the body during that activity. One metabolic equivalent (MET) is the amount of oxygen (O2) used while at rest/sitting still, which is 3.5 milliliters O2 per kilogram of body weight per minute. Physical activities that burn 3.0 to 5.9 METs are considered moderate intensity, and those that burn 6.0 METs or more are considered vigorous intensity.
Brisk walking usually falls into the moderate-intensity MET category and running falls into the vigorous category.
What are “non-responders” and how can they still use exercise to help their health?
The term “non-responders” is used to describe people who do not get certain anticipated benefits of exercise, such as improved glucose or blood pressure. However, the good news is that even if a specific benefit isn’t achieved from exercise therapy, other benefits are often attained. For example, if someone’s blood sugars are unchanged by exercise, they may gain increased cardiorespiratory fitness. Sometimes, the lack of “response” may also be due to the type of exercise (aerobic vs. resistance) or the timing of exercise, and that is why to achieve someone’s desired benefits from exercise an individualized approach is key.
What is GLUT4 and how does it translate into exercise being a positive step for diabetes?
GLUT4, a glucose transporter that insulin stimulates to bring glucose inside the cell, is also stimulated by muscle contraction during exercise without insulin. This increases transport of glucose into muscle cells and is one way that exercise can acutely decrease blood sugar levels even when someone has insulin resistance or does not produce insulin.
What is some ongoing clinical research underway on campus on this topic?
My colleagues Drs. Jane Reusch and Judy Regensteiner are conducting an NIH study to understand how exercise training improves cardiac and skeletal muscle function in adults with and without type 2 diabetes. They are currently seeking volunteers who are not exercising and not on certain types of diabetes medications, such as SGLT2 inhibitors or GLP-1 receptor agonists. In this study, people can learn a lot about the function of their heart, skeletal muscle and blood vessels and receive an individualized exercise program.
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