The Best Type of Exercise and What Time to Do It If You Have Type 2 Diabetes

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A study published in the Journal of the American College of Cardiology reported that up to 40 percent of Americans will be at risk for developing Type 2 diabetes by 2060, and researchers are racing to find a way to slow its progression.

Exercise can prevent, delay, and even reverse Type 2 diabetes. Recent research suggests that the type, timing, and frequency of exercise all play a vital role in optimal glucose control for Type 2 diabetics.

Exercise and Blood Sugar Control

Diet is a significant factor in controlling blood glucose and insulin sensitivity, and growing evidence suggests that exercise may be even more critical.

A recent study published in The American Journal of Medicine Open (AJM Open) provides a comprehensive summary of the type and timing of exercise for controlling blood glucose and improving insulin sensitivity.

The study compared aerobic exercise, resistance exercise, and the combination of the two to determine how they affect insulin sensitivity, blood glucose levels, and overall cardiometabolic health. Researchers also evaluated how the intensity of exercise and the time of day when the activity is undertaken influence glucose control.

“The challenge with this is that most, if not all, people know exercise is good for them, but they don’t know the best approach,” study author Steven Malin, an associate professor in the Department of Kinesiology and Health at Rutgers School of Arts and Sciences, told Rutgers Today.

Best Types of Exercise

Mr. Malin and his team analyzed several studies to summarize types of exercise and the best time to do them to improve blood glucose levels and insulin sensitivity. “I think of exercise as a drug,” he said.

Aerobic Activity

Aerobic exercises such as walking, jogging, biking, and swimming use large muscle groups and usually increase heart and respiratory rates. Aerobic activity lowers blood glucose levels and increases insulin sensitivity using two pathways.

First, muscle cells use insulin in the bloodstream to take up glucose during exercise. The same cells can also take in glucose without the help of insulin. By using both pathways, muscle cells remain sensitive to insulin for up to 48 hours.

Muscle cells also store more glucose inside the muscle for future use, leaving less traveling around in the blood, which is ultimately the goal. According to study researchers, participating in bouts of exercise favors insulin sensitivity and contributes to better aerobic fitness, thereby reducing cardiovascular disease and all-cause mortality in Type 2 diabetics, regardless of body weight.

Recommendations by the American Diabetes Association (ADA) include getting 150 minutes of moderate- to vigorous-intensity aerobic exercise per week, with no more than two consecutive days without physical activity.

The ADA suggests the following ways to spread out the 150 minutes so the goal doesn’t seem unreachable:

• 50 minutes three times per week.
• 30 minutes five times per week.
• 25 minutes six times per week.

And that time can be split into sessions throughout the day of at least 10 minutes each since exercise sessions lasting 10 minutes or more benefit heart health the most.

The study also showed that exercise can improve overall glycemic control. For instance, overweight individuals with an exercise routine of 45 to 60 minutes per session four times per week, working at 50 to 75 percent maximum effort for six months, reduced fasting blood glucose by 18.58 milligrams/deciliter and reduced insulin levels by 2.91 milliunits/liter compared with the group that didn’t exercise.

Researchers reviewed an epidemiological study that reported a 21 percent reduction in diabetes-related death after a 1 percent reduction in glycated hemoglobin (HbA1c or A1c).

The researchers also reviewed a meta-analysis that found that 1,003 people with Type 2 diabetes had an average drop in systolic blood pressure of 5.6 millimeter of mercury (mmHg), a decrease in diastolic blood pressure of 5.5 mmHg, and a 0.3 millimole/liter reduction in triglyceride level and total cholesterol after aerobic exercise training interventions.

Resistance Training

Resistance training can augment aerobic exercise by providing variety and increasing adherence to an overall training regimen. It can also help combat low muscular strength and muscle mass decline, independent risk factors in Type 2 diabetes.

Resistance exercises involve the contraction of muscles with external weights or body weight. The American College of Sports Medicine (ACSM) guidelines suggest resistance or muscle-strengthening activities at a moderate to high intensity involving major muscle groups two to three days per week, but not on consecutive days. They should include 10 to 15 repetitions per set, with one to three sets per specific type of exercise.

According to the ACSM, resistance training in older adults with Type 2 diabetes resulted in a 10 to 15 percent improvement in strength, lean mass, blood pressure, blood lipid levels, bone mineral density, and insulin sensitivity. Resistance training also led to more significant reductions in A1c.

“The combination of aerobic exercise and weightlifting is likely better than either alone,” Mr. Malin said.

Best Time to Exercise

Choosing the time of day and whether to exercise before or after a meal can significantly affect long-lasting blood glucose control and prevent spikes throughout the day.

Circadian rhythm has a substantial influence on glucose control. There are several physiological processes, such as glucose tolerance, circulating insulin, body temperature, and hormones, that scientists have started to associate with glycemic control.

People with Type 2 diabetes tend to have a disrupted circadian rhythm since their insulin sensitivity is often better in the evening but worsens throughout sleep and into the morning, raising blood glucose by the time they wake up. Exercising at the right time of day could improve glucose control.

According to the AJM Open study, most research has found that exercise in the afternoon or evening may be better for glucose control and insulin sensitivity than the same activity done in the morning, though not all studies yielded the same results. Some research suggests that morning exercise is better for managing weight and keeping to an exercise routine, which could mean the best time to exercise may be outcome dependent.

However, a consensus statement from the ACSM concluded that exercising after a meal reduces glucose levels by attenuating acute glucose spikes, regardless of the exercise type or intensity. A duration of 45 minutes or more provides the most consistent benefits.

Take Breaks From Sitting

Adults in the United States spend an average of eight hours per day being sedentary, which has become an independent risk factor for cardiovascular disease and Type 2 diabetes.

To offset the adverse effects of sitting, the AJM Open study suggests getting up and walking every 30 minutes, which can improve glucose and insulin sensitivity in people with Type 2 diabetes.

A recent study published in iScience found that a simple exercise coined the “soleus pushup” can lower post-meal blood glucose by up to 50 percent.

The soleus muscle runs from the back of the knee down the back of the shin bone to the heel. It’s used when walking and running and helps keep us from falling forward while standing. It’s built for endurance and doesn’t rely heavily on intramuscular glycogen, so it gets most of its fuel from glucose in the bloodstream.

The soleus pushup is done while sitting. According to the study, moving the muscle up and down yielded a 52 percent improvement in blood glucose and 60 percent less insulin requirement over three hours after a glucose drink.

The soleus pushup. APword/Shutterstock

“The soleus’s lower-than-normal reliance on glycogen helps it work for hours effortlessly without fatiguing during this type of muscle activity because there is a definite limit to muscular endurance caused by glycogen depletion,” Marc Hamilton, professor of Health and Human Performance at the University of Houston and primary author of the study, told the University of Houston.

In a position statement, the ADA said that simply interrupting prolonged sitting with 15 minutes of walking after a meal and three minutes of light walking and light resistance activities every 30 minutes can improve glucose control.

Blood Glucose and Insulin

Better glucose control means less risk of complications caused by diabetes, including cardiovascular disease and peripheral nerve damage.

Glucose is fuel for the body, particularly the brain, and an adequate amount of glucose must constantly circulate in your bloodstream. When blood sugar is too low, the brain doesn’t have enough fuel and can become comatose; when it’s too high, it can damage our blood vessels.

A healthy body has many physiological processes to keep blood sugar within that tight range, and one of the most important is insulin.

The pancreas secretes insulin after a meal, and skeletal muscles need insulin to help take glucose into their cells. The cells of people with diabetes or prediabetes are less sensitive to insulin, often called insulin resistance.

The low insulin sensitivity is initially brought on by eating excessive amounts of sugary and processed foods and reduced physical activity. The pancreas secretes insulin to compensate for high blood glucose levels, but as cells become less sensitive, more glucose circulates in the blood, and prediabetes or Type 2 diabetes becomes imminent.

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“In short, any movement is good, and more is generally better,” Mr. Malin said. “The combination of aerobic exercise and weightlifting is likely better than either alone. Exercise in the afternoon might work better than in the morning for glucose control, and exercise after a meal may help slightly more than before a meal.”

Overall, the type and timing of exercise are vital to glucose control. Still, the most important thing is to stay active, even if it’s breaking up long periods of sitting with walking around for five minutes. The more you move, the better glucose control you will have.