A new study suggests that people who spend time walking or even just standing instead of sitting may be at lower risk of type 2 diabetes.
The purpose of the study was to quantify associations between sitting time and glucose, insulin and insulin sensitivity by considering reallocation of time into standing or stepping.
Study co-author Dr. Joseph Henson, a diabetes researcher at the University of Leicester added that the ”findings from this study provide further encouraging evidence that simply substituting standing for sitting throughout the day may improve markers of type 2 diabetes.” Previous research has linked sedentary time to type 2 diabetes.
Over the past decade, sedentary behavior, defined as any waking behavior characterized by a low energy expenditure while in a sitting or reclining posture, has emerged as a potential independent risk factor for cardiometabolic health, chronic disease and mortality. However, epidemiological research to date has either assessed sedentary behavior using self-reported questions around television viewing, screen time and total sitting time, or used objective measures such as waist-worn accelerometers which infer sitting or reclining posture through lack of movement.
This is the first study to examine associations between objectively measured sitting time and insulin sensitivity. The population used in this study, that is, those identified as being at high risk of developing type 2 diabetes, are broadly representative of those referred to diabetes prevention programs, therefore having direct relevance for future diabetes prevention.
For the current study, researchers asked 435 adults at risk for developing diabetes to wear activity monitors around the clock for one week to see how much time they spent sitting, standing and walking.
Study participants were 67 years old on average. Most of them were either overweight or obese, and about one third had a family history of diabetes. Each day, participants spent an average of 9.4 hours sitting or lying down during their waking hours. This included a total of about 4.2 hours of brief periods of sitting for no more than a half hour, as well as 5.4 hours of prolonged bouts of sitting that lasted at least 30 minutes. In addition, participants typically spent an average of 4.5 hours a day standing and 1.7 hours a day walking.
People who replaced 30 minutes of prolonged sitting time with shorter bouts of sitting had a 4 percent reduction in fasting insulin levels, the researchers calculated. If participants replaced prolonged sitting with standing, however, they had a 5 percent drop in fasting insulin levels, and walking instead was associated with an 11 percent difference, they reported online January 1st in BMJ Open.
The study didn’t find an association between blood sugar or insulin levels when people swapped short periods of sitting for standing, however. Stepping instead of sitting for short periods was linked to a 7 percent drop in fasting insulin.
When the body moves, it signals muscles and cells that will need fuel and they start absorbing sugar from the blood. When people are sedentary, these signals don’t go out. Even though the results mirror other studies linking reduced sedentary time to a lower diabetes risk, the use of statistical models rather than a controlled experiment makes it hard to see what would happen if people cut back on sitting in real life.
After adjustment for confounders, including waist circumference, reallocation of prolonged sitting to short sitting time and to standing was associated with 4% lower fasting insulin and 4% higher HOMA-IS, reallocation of prolonged sitting to standing was also associated with a 5% higher Matsuda-ISI. Reallocation to stepping was associated with 5% lower 2-hour glucose, 7% lower fasting insulin, 13% lower 2-hour insulin and a 9% and 16% higher HOMA-IS. Reallocation of short sitting time to stepping was associated with 5% and 10% lower 2-hour glucose and 2-hour insulin and 12% higher Matsuda-ISI.
This unique study modelled the association of reallocating time spent sitting (accumulated in short and prolonged bouts) to standing or stepping, measured with a robust objective assessment of posture, on associations with glucose, insulin and insulin sensitivity. More importantly, these associations were observed when reallocating time in prolonged sitting to standing or stepping or reallocating time in short sitting to stepping. Stronger associations were observed for stepping and no associations were observed for reallocating short sitting to standing.
In conclusion, this study provides novel evidence for the potential benefits on glucose, insulin and insulin sensitivity when substituting small amounts of sitting time for standing and even more benefits when stepping, and greater benefits may improve 2-hour glucose, fasting and 2-hour insulin and insulin sensitivity.
Practice Pearls:
• Stepping instead of sitting for short periods was linked to a 7 percent drop in fasting insulin.The benefits of moving rather than sitting is something that we need to let our patients know. They don’t need to run a marathon, only take short breaks from sitting and move.
• The results demonstrate that reallocating a small amount of sitting time into time spent standing or walking is associated with better insulin sensitivity in a population that is potentially at high risk of developing T2DM.
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