One benefit of exercise is that it lowers the risk of type 2 diabetes. One way it does this is by helping with weight control and by reducing the risk of obesity, a major risk for pre-diabetes and type 2 diabetes. Another benefit of exercise is that it improves insulin sensitivity, the way cells handle glucose. Insulin resistance, or low insulin sensitivity, is a precursor to type 2 diabetes and is sometimes referred to as prediabetes. Shockingly, more than half of all people over the age of 65 have prediabetes and around 25% of those people will develop type 2 diabetes, eventually.-
People who have prediabetes and type 2 diabetes are suffering from insulin resistance, a condition where cells don’t take up glucose as readily in response to insulin. As such, more insulin must be released, and this places added stress on the beta-cells, the insulin-producing cells in the pancreas. Over time, this stress can cause the beta-cells to burn out and have trouble producing enough insulin to meet the body’s demands. That’s the point at which prediabetes becomes full-blown diabetes. Insulin resistance and elevated blood sugar are also linked with premature aging.
How does this state of insulin resistance come about? Insulin resistance and type 2 diabetes have a genetic component but are strongly influenced by environmental and lifestyle factors. So, what you eat, how much you sleep, how often you move your body, and how you manage stress matter! Exercise is one of those lifestyle factors. Research shows a combination of diet, exercise, and weight loss can improve how cells process glucose. But exercise alone has benefits as well. A meta-analysis of 28 studies showed that moderate-intensity exercise, at least 150 minutes per week, was associated with a significant reduction in the risk of developing type 2 diabetes. Higher intensity exercise seems to have greater benefits than less intense exercise.
Also, studies show that aerobic exercise and resistance training in combination may have greater benefits than either in isolation. In fact, a study found that every 10% increase in skeletal muscle mass relative to total body weight was linked with a 12% reduction in the risk of pre-diabetes. We often focus on aerobic exercise for preventing diabetes, but resistance training improves insulin sensitivity as well.
Can a Single Exercise Session Boost Insulin Sensitivity?
Most research looking at exercise and type 2 diabetes has focused on the longer-term benefits of exercise on blood sugar control and type 2 diabetes risk–but who doesn’t love immediate gratification? Could a single exercise session bump up your insulin sensitivity?
In one small study, researchers asked 11 previously sedentary, obese adults to take part in a study. During two different trials, they exercised enough to burn 350 calories. The only difference was the intensity and duration with which they exercised. One session was shorter and more intense (65% of V02 max) while the other was longer and lower in intensity (50% of V02 max).
The results? Even the lower intensity exercise session was associated with improvements in insulin sensitivity, and the improvements persisted even the following day. It’s a small study, but it appears that, at least for obese people, a single exercise session, even one that’s not high intensity can improve how cells handle glucose.
Longer term, it also appears that aerobic exercise enhances insulin sensitivity even in the absence of an increase in aerobic capacity or V02 max. This suggests that even lower intensities and volumes of exercise are beneficial. However, high-intensity training and moderate-intensity exercise of longer duration seem to offer greater improvements.
How Exercise Increases Insulin Sensitivity
Exercise increases the density of receptors on the surface of skeletal muscle called GLUT4 receptors. These receptors remove glucose from the bloodstream and deliver it to the muscle cell even without insulin. In fact, research shows high-intensity interval training increases the number of GLUT4 receptors on the surface of muscle cells by up to 160%. Therefore, glucose gets into muscle cells easier due to the availability of more receptors to take it up. Exercise, via its impact on GLUT4 receptors, is like a free ride for glucose! No insulin required.
Longer term exercise lowers the risk of type 2 diabetes in other ways. It lessens gains in body fat that happen as we age and helps keep the visceral fat that accumulates around the waist and tummy in check. Visceral fat is the most dangerous kind of fat, as it produces inflammatory chemicals that may contribute to chronic health problems. The best way to keep tabs on visceral fat is to measure and regularly follow your waistline. For health purposes, your waistline should be no larger than half of your height. As we age, waist size gradually creeps up, but it’s more than an aesthetic issue. It’s a sign of worsening metabolic health.
The Bottom Line
Regular physical activity, both aerobic and resistance training, are healthy lifestyle habits that can lower the risk of prediabetes and type 2 diabetes. It does it more than one way too–by improving insulin sensitivity and by helping with loss of body fat, particularly visceral fat. Combine it with a healthy, whole food unprocessed diet, adequate sleep, and stress control, and you have the makings of a blood-sugar friendly lifestyle. With prediabetes and type 2 diabetes being so common, you can’t afford to take lifestyle steps that will lower your risk. Exercise has so many health benefits that extend beyond insulin sensitivity too. Keep moving your body and make sure you’re strength training regularly too.
References:
· Diabetes Care. Volume 314Issue 6. June 2018. Pages E564-E571.
· BMJ Open Sport Exerc Med. 2016; 2(1): e000143.
· American Journal of Physiology. Endocrinology and Metabolism. “Resistance training recovers attenuated APPL1 expression and improves insulin-induced Akt signal activation in skeletal muscle of type 2 diabetic rats” (2018)
· Up-to-Date. “Prevention of type 2 diabetes mellitus”
· Ann Intern Med. 2015;163(6):437.
· Lancet. 2008;371(9626):1783.
· MedPage Today. “Muscle Mass Knocks Out Insulin Resistance”
· Diabetes Metab Res Rev 2014;30:257–68.
· Medscape. “Exercise: How Does It Promote Insulin Sensitivity?”
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