Type 2 diabetes patients who were physically active in the afternoon have greater reductions in blood sugar

More than 37 million Americans have diabetes, and 90-95% of this population is diagnosed with type 2 diabetes. Lifestyle interventions, such as a healthy diet and a regular exercise program, are diabetes management methods.

A new study from a collaboration between researchers at Brigham and Women’s Hospital, a founding member of the Mass General Brigham Health System, and the Joslin Diabetes Center, part of Beth Israel Lahey Health, uses data from Look AHEAD (Action for Health in Diabetes) study, a randomized controlled trial that compared intensive lifestyle intervention with diabetes support and education in patients diagnosed with type 2 diabetes and overweight or obesity to follow development cardiovascular disease over time. In the current study, the research team assessed whether physical activity at certain times of the day was associated with greater improvement in blood sugar control. Their results suggest that patients with type 2 diabetes who were physically active in the afternoon had the greatest improvements after one year in the trial. The team’s results are published in Diabetic treatments.

In this study, we showed that adults with type 2 diabetes had the greatest improvement in blood sugar control when they were most active in the afternoon. We know that physical activity is beneficial, but what our study adds is new understanding that the timing of activity may also matter.

Jingyi Qian, PhD, corresponding co-author and division of sleep and circadian disorders, Brigham.

Doctors recommend that patients with diabetes participate in regular physical activity as a method of managing their blood sugar levels. High blood sugar can put people with type 2 diabetes at risk for heart disease, visual impairment and kidney disease.

The team analyzed physical activity data from the first and fourth years of the Look AHEAD study, which included data from more than 2,400 participants. During the study, participants wore an accelerometer recording device at the waist to measure physical activity. When Brigham and Joslin’s team looked at Year 1 data, they determined that those who engaged in moderate-to-vigorous physical activity in the afternoon had the greatest reduction in blood sugar. Comparing 4 year data, the afternoon group maintained a reduction in blood sugar. Additionally, the afternoon group also had the highest chance of stopping their glucose-lowering/diabetic medications.

Brigham and Joslin’s team note that their investigation has limitations; for example, their study is observational and does not measure confounders like sleep and food intake.

In future studies, the team could test their findings experimentally to investigate the underlying mechanisms that may explain why time of day of activity may influence blood sugar control. From there, the team may be able to provide patient-specific physical activity recommendations.

Timing seems to matter. In the future, we may have more data and experimental evidence so that patients can give more personalized recommendations.

Roeland Middelbeek, MD, co-corresponding author and associate researcher, Joslin Diabetes Center.


Brigham and Women’s Hospital

Journal reference:

Qian, J. et al. (2023) Association of timing of moderate-to-vigorous physical activity with changes in glycemic control over 4 years in adults with type 2 diabetes from the Look AHEAD trial. Diabetic treatments. doi.org/10.2337/dc22-2413.

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