Type 2 Diabetes & Exercise: Time Matters

November 5, 2016

Two diabetes studies looked at timing of exercise and glycemia levels, and length of time and degree of intensity of exercise and diabetes risk.

Clinicians should advise their patients with type 2 diabetes mellitus (T2DM) to take a walk after eating to lower postprandial hyperglycemia, according to a new study.

Regular physical activity is a cornerstone of diabetes management, and current guidelines recommend that T2DM patients get a minimum of 150 minutes of moderate physical activity each week, or about 30 minutes a day over five days. Daily exercise can be completed all at once or broken up into different times throughout the day.  

The timing of physical activity may be important, particularly after the evening meal, according to researchers led by Andrew N. Reynolds, MD, from the University of Otago in Dunedin, New Zealand. They conducted a randomized, cross-over study of 41 adults with type 2 DM, mean age 60 years, with mean diabetes duration of 10 years.1 For periods of 2 weeks, the patients walked 30 minutes each day or walked for 10 minutes after each main meal.

Physical activity was measured by accelerometers over the full intervention, and glycemia was measured using continuous glucose monitoring in five-minute intervals over 7 days. The primary outcome was postprandial glycemia, which was assessed during the three hours after a meal.

Postprandial glycemia levels dropped 12%, on average, when patients walked after meals as compared to on a single daily occasion. There was a 22% glycemic drop in the three-hour period following the evening meal. “The improvement was particularly striking after the evening meal when the most carbohydrate was consumed and sedentary behaviors were highest,” stated the researchers.

They concluded that “the benefits relating to physical activity following meals suggest that current guidelines should be amended to specify post-meal activity, particularly when meals contain a substantial amount of carbohydrate.”

Higher Activity Levels

Another new study shows that higher levels of physical activity may help lower the incidence of T2DM. This study found a dose-response relationship between exercise and the development of T2DM.2

Researchers led by Andrea Smith, a PhD candidate in public health at the Health Behaviour Research Centre at University College London, United Kingdom, conducted a meta-analysis of 23 cohort studies in 1.2 million nondiabetic individuals from the United States, Asia, Australia, and Europe.

The results show that the participants who achieved an 11.25 metabolic equivalent of task (MET) hours/week of moderate activity (equivalent to 150 minutes per week of moderate activity) had a 26% reduction in the risk of developing T2DM.

Achieving twice this amount of physical activity was associated with a risk reduction of 36%, with further reductions at higher doses -- 60 MET hours/week led to a 53% risk reduction. Results for the MMET hour/week dose–response curve were similar for moderate intensity physical activity, but benefits were greater for higher intensity physical activity and smaller for lower intensity activity, the researchers stated.

They suggested that when it comes to physical activity, “the greatest relative benefits are achieved at low levels of activity, but additional benefits can be realized at exposures considerably higher than those prescribed by public health recommendations.”

1. Reynolds AN, et al.  Advice to walk after meals is more effective for lowering postprandial glycaemia in type 2 diabetes mellitus than advice that does not specify timing: a randomised crossover study. 2016 Oct 17.

2. Smith AD, et al. Physical activity and incident type 2 diabetes mellitus: a systematic review and dose–response meta-analysis of prospective cohort studies. 2016 Oct 18.