Healthcare providers often encourage people who have Type 2 diabetes to walk — even if it's only for 30 minutes a day — to help lower their blood sugar. But new research from New Zealand's University of Otago suggests that walking after meals yields better, more efficient results than walking at any other time of the day.
Forty-one patients with Type 2 diabetes were fitted with accelerometers to measure their physical activity and devices that measured their blood sugar every five minutes. They were instructed to walk either for 30 minutes a day as advised by guidelines, or to walk for 10 minutes after each main meal.
Dr. Andrew Reynolds found that post-meal blood sugar levels dropped 12% on average for participants who walked after meals compared with other times of the day. In fact, he noted a 22% reduction in blood sugar in participants who walked after evening meals specifically, even when those meals were carbohydrate-heavy.
Professor Jim Mann says that post-meal glucose is regarded as an important target in managing Type 2 diabetes, given its independent contribution to overall blood sugar control and cardiovascular risk.
Professor Mann and his colleagues write that "postprandial physical activity may avoid the need for an increased total insulin dose or additional mealtime insulin injections that might otherwise have been prescribed to lower glucose levels after eating. An increase in insulin dose might, in turn, be associated with weight gain in patients with Type 2 diabetes, many of whom are already overweight or obese."
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 carbohydrates, the researchers conclude. Their findings are published this week in the international journal Diabetologia.
Of course, it's not just the timing of physical activity that can benefit people with Type 2 diabetes. A second U.K.-based study in the same edition of the journal shows that increasing your amount of activity also aids blood sugar control.
Andrea Smith and colleagues examined the results of 23 cohort studies on the relationship between physical activity and incidence of Type 2 diabetes. The meta-analysis included 1,245,904 individuals who did nothave diabetes from the United States, Asia, Australia and Europe, among whom 82,319 incident cases of Type 2 diabetes arose during the studies' follow-up periods, ranging from 3 to 23 years. The authors found a 26% reduction in the risk of developing the chronic disease among participants who achieved 11.25 metabolic equivalent of task, or MET, hours per week — in other words, 150 minutes per week of moderate activity, the minimum amount recommended by public health guidelines.
Their results also suggest that the benefits of being physically active extend considerably for levels above those minimum recommendations.
Current public health guidelines recommend a minimum of 150 minutes of moderate to vigorous physical activity or 75 minutes of vigorous physical activity a week. Self-reported data, however, suggests that as many as a third of adults globally are not meeting these targets.
Previous trials conducted in patients with impaired blood glucose tolerance provided some understanding of how physical activity could have prevented the development of Type 2 diabetes in high-risk groups. But the majority of these studies included changes to both diet and physical activity, making it difficult or impossible to isolate the effects of exercise alone.
While physical activity is known to reduce the risk of Type 2 diabetes, the shape of the dose-response relationship has been uncertain. The authors sought to examine whether significant health benefits could be realized from levels of exercise considerably higher than those currently recommended.
"Providing quantitative estimates regarding the dose-response relationship is essential for approximating how changes in levels of physical activity in the general population would affect disease incidence, and would support more nuanced guidance to the public and evidence-based dialogue in clinical settings," says Dr. Søren Brage.
In short, the study conducted by Smith and her colleagues demonstrates that although some exercise is good, more is even better. Building environments that encourage physical activity as part of everyday life may prevent substantial personal suffering — not to mention economic burden. "Given the current obesity and diabetes epidemic there is a pressing need to make our towns and cities places where getting around on foot or by bike feels like the natural choice," the team concludes.