If you're one of the millions of folks living with type 2 diabetes, you know that regular exercise can help you keep your blood sugar in check.
Now, new research suggests that working out in the afternoon may help maximize these benefits.
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The new study wasn't designed to say how, or even if, exercising in the afternoon is better for blood sugar control, but researchers have some theories.
"If we exercise after a meal, it may be more beneficial than after fasting, and if you exercise in the afternoon, it is likely after a meal," said study author Jingyi Qian. She is an associate physiologist and associate director of the medical chronobiology program at Brigham and Women's Hospital in Boston.
By contrast, folks who work out in the morning may not eat breakfast until after they are finished.
This doesn't mean that you should skip your workout if you can't find time in the afternoon, Qian cautioned. "The best time to exercise is whenever you can and wherever you can."
For the study, more than 2,400 people with type 2 diabetes wore a device on their waist that tracked physical activity for a week when the study began and four years later. They were grouped based on the time of day that they exercised at one year and four years.
Afternoon exercisers, those who worked out between 2 p.m. and 5 p.m., showed a greater improvement in blood sugar control at one year, which was maintained after four years. What's more, the folks who exercised in the afternoon were more likely to no longer need glucose-lowering diabetes medications.
The study didn't look at specific types of exercise. "This is an emerging area, and we will know more with more studies," Qian said.
The study appears in the May 25 issue of Diabetes Care.
It's too early to make any sweeping recommendations about the best time of day to exercise for people with type 2 diabetes, said Tanya Halliday, an assistant professor in the department of health and kinesiology at the University of Utah Health.
"We don't yet know if the timing of exercise itself influenced these outcomes or if there are differences between people who self-select to exercise at different times of day," said Halliday, who wasn't involved in the new study.
For example, timing of exercise may result in changes to diet or sleep patterns that drive the improvements in blood sugar and reduced use of glucose-lowering medications, she said.
"It will be important to see if this observation is replicated in other analyses," Halliday said.
Her advice? "I would encourage people to exercise when they are most likely to consistently do it, whether that is first thing in the morning or the afternoon," she said.
"Personal preference, work schedule, and when workout buddies may be available all influence when anyone chooses to exercise, which is perfectly fine," Halliday added.
Aim to meet the current physical activity guidelines from the American Diabetes Association, which call for 150 minutes or more of moderate-to-vigorous intensity aerobic activity each week and two or three weekly sessions of resistance or strength training exercise.
"I would strongly encourage people with type 2 diabetes to discuss their exercise plans with their medical care team so that appropriate follow-up and changes to medications can be made as the exercise program progresses," Halliday said.
Dr. Ruchi Mathur agreed. She is an endocrinologist at the Cedars-Sinai Diabetes Outpatient Treatment and Education Center in Los Angeles.
She pointed out that everyone who exercised saw a reduction in blood sugar, regardless of timing. "It was more pronounced in those with afternoon activity," said Mathur, who has no ties to the new research.
"Movement is the key, as is consistency," she said. "Do something you enjoy, and do it with someone you enjoy, and perhaps, make some time in the afternoon to accomplish those goals."