Physical Activity and Type 2 Diabetes: When and How Much?
Both timing and amount of physical activity is important for preventing or managing type 2 diabetes.
Not only is the amount of physical activity important to the prevention of type 2 diabetes, but the timing may improve management of the condition.1
According to findings from a study published in Diabetologia, higher levels of physical activity were linked to lower incidence of type 2 diabetes, although any exercise had health benefits. In terms of management of existing type 2 diabetes, a second study showed that short bouts of physical activity, like brief walks, at certain times a day resulted in significantly lower glucose levels.
How Much Exercise is Beneficial?
Interventional and observational studies suggest a link between physical activity and risk for diabetes, although how this relationship is not fully understood.
“It is also difficult to evaluate the benefit of the whole [physical activity] exposure continuum from trials, as most intervention studies focus on shifting participants' behaviours towards the recommended level of exercise rather than assessing the benefits of changes at the lowest ends of the normal [physical activity] spectrum, or the additional benefits gained at the highest level,” Andrea D. Smith, a PhD student in the Health Behaviour Research Centre at University College London, and colleagues wrote in the first study.
Senior study author Søren Brage, PhD, of the MRC Epidemiology Unit at the University of Cambridge, however, highlighted the importance of learning more about this relationship.
“Providing quantitative estimates regarding the dose-relationship is essential for approximating how changes in levels of physical activity in the general population would impact disease incidence, and would support more nuanced guidance to the public and evidence-based dialogue in clinical settings,” Dr Brage said in a press release.2
To further evaluate the effects of physical activity on diabetes risk as well as the potential for a dose-response relationship, Ms Smith and colleagues conducted a systematic literature review of 23 cohort studies involving 1,245,904 participants without diabetes assessing the association between physical activity and incidence of type 2 diabetes.
During the studies' follow-up periods, which ranged from 3 to 23.1 years, 82,319 participants developed type 2 diabetes.1 Compared with those who were inactive, achieving the equivalent of 150 minutes per week of moderate physical activity (11.25 metabolic equivalent of task [MET] hours per week), which is the currently recommended amount in public health guidelines, was linked to a 26% lower risk for developing diabetes (95% CI, 20%-31%) while achieving twice that amount was linked to a 36% lower risk for developing diabetes (95% CI, 27%-46%).1 Risk reduction was also greater with further increases in physical activity (60 MET hours per week, 53%).1 In terms of the dose-response curve, higher-intensity exercise yielded greater benefits while lower-intensity exercise yielded smaller benefits.1
"Our results suggest that the health benefits of physical activity are apparent even at levels below the recommended levels, compared to not doing any activity, but also that benefits are greater still for those who exceed the minimum recommendations, such that even when physical activity was as high as 60 MET hours per week benefits continued to occur, with the risk of developing type 2 diabetes being more than halved in those individuals," said Dr Brage.2
Joint senior study author James Woodcock, PhD, of the Centre of Excellence for Diet and Activity Research at the University of Cambridge, noted that these data add to what clinicians and researchers know about physical activity's effects on type 2 diabetes.
“We already knew that [physical activity] has a major role to play in tackling the growing worldwide epidemic of type 2 diabetes,” Dr Woodcock said in the release.2 “However, policy makers rely on models that estimate how much benefit they would get from a policy that increased population levels of activity. By combining the studies together in this way provides a strong evidence base on which to build these models.”
Ms Smith also added that the findings have practical implications as well and offer insight into how people should view physical activity. “Our study favors a ‘some is good but more is better' guideline, in which specific targets are mainly used for a psychological effect. There is no clear cut-off at which benefits are not achieved and health benefits increase at activity levels well beyond current recommendations,” she said. “Building environments that encourages physical activity as part of everyday life may prevent substantial personal suffering and economic burden.”