Afternoon exercise shown to induce greater reduction in blood glucose levels among people with type 2 diabetes

Exercise improve blood glucose levels in people with type 2 diabetes, reduces cardiovascular risk factors, contributes to weight loss, and improves well-being. Current guidelines recommend that most adults with diabetes should engage in 150 min or more of moderate-to-vigorous intensity exercise weekly, spread over at least 3 days/week, with no more than two consecutive days without exercise. However, the best timing of exercise activity is unclear. The Look AHEAD (Action for Health in Diabetes) trial was the largest randomised trial evaluating a lifestyle intervention in older adults with type 2 diabetes compared with a diabetes support and education control group. The intensive lifestyle intervention group underwent at least 175 min/week of unsupervised exercise. Although major cardiovascular events were the same in both groups, (likely due to greater use of cardioprotective medications in the diabetes support and education group), the intensive lifestyle intervention group achieved significantly greater sustained improvements in weight loss, cardiorespiratory fitness, blood glucose and blood pressure levels, and provided very strong evidence of profound health benefits from intensive lifestyle intervention. In a further analysis of the Look AHEAD study, researchers from the Brigham and Joslin Diabetes Centre assessed whether physical activity at certain times of day was associated with greater improvement in blood glucose control. The investigators analysed physical activity data from the first and fourth years of the Look AHEAD study, which included data from over 2400 participants. During the study, participants wore a waist accelerometry recording device to measure physical activity. Comparing data from year 1 and year 4 of the study, the investigators observed that those who engaged in moderate-to-vigorous physical activity in the afternoon had the greatest reduction in blood glucose levels, maintained these reductions in blood glucose levels and were more likely to stop their glucose-lowering/diabetes medications. The study was published in the journal Diabetes Care.¹ While the study has limitations due to its residual confounding effects such as impact of circadian rhythm, sleep, dietary intake and occupation, this study provided additional understanding on the importance of timing of physical activity on exercise induced blood glucose lowering.

This study was funded by the National Heart, Lung, and Blood Institute (K99-HL-148500, R01-HL140574), National Institute on Aging (RF1AG059867 and RF1AG064312), and National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) (K23-DK114550).