Diabetes in older adults: is it related to sedentary time and when it’s interrupted?

What is it about?

For one week, we measured how 6116 older women spent their sedentary time using a research-grade activity monitor. All the women in this research project have participated in the largest study of women’s health in the United States (The Women’s Health Initiative) for over 20 years. This gave us detailed information for each woman, including whether they had been diagnosed with diabetes by a doctor. We looked at two aspects of their sedentary time. 1) The overall amount of time the participants spent sedentary each day. We found that women who were sedentary for more than 10 hours per day had twice the odds of diabetes compared to women sedentary less than 8 hours per day. We used additional information to control for factors related to diabetes and sedentary time in our analysis (e.g. diet, moderate and vigorous physical activity, alcohol, smokers, family history of diabetes) giving us more confidence that sedentary time was driving the association. 2) Sedentary time patterns (1), which explain how the women typically accumulated their sedentary time (i.e., in long bouts with few interruptions vs. in short bouts with many interruptions). We found that the odds of having diabetes were considerably higher among women who were often sedentary for long continuous periods compared to women who regularly interrupted their sedentary time. Our results align well with those of previous studies. They too indicate that older women who spend large proportions of the day sedentary, and those who are sedentary for long uninterrupted periods, might be at higher risk of diabetes. This is irrespective of other factors such as diet and moderate and vigorous physical activity levels (which could include brisk walking or cycling). One important limitation of this study is that we did not measure sedentary behaviors before the women got diabetes, and therefore we cannot tell which came first. High amounts of sedentary time and poor sedentary patterns could contribute to developing diabetes, though diabetes (and its consequences) could also cause women to develop bad sedentary habits. To address this possibility of ‘reverse causation’, we conducted additional tests which are detailed in the paper. The results suggested that reverse causation did not entirely explain our findings. References: 1. Diagram of sitting time accumulation patterns. https://figshare.com/articles/Sitting_Accumulation_Patterns_2108-06-06_png/6452753

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Why is it important?

The findings were important for a few key reasons: • It is the first reported association of accelerometer-measured sedentary time and diabetes in a sample of older adults most of whom were over the age of 80. • The findings were very similar to several studies of younger adults, supporting the idea that sedentary time is related to diabetes across the entire adult age spectrum. We further explored this idea by rerunning analyses separately in women less than 80 years old and those greater than 80; the results were nearly identical for both groups. • We provided evidence that the association between sedentary time and diabetes may be generalizable to older adults with diverse diabetes-risk profiles. To do this, we repeated our analyses in subgroups of women with high and low physical activity levels, high and low physical functioning, who were from different racial-ethnic backgrounds, who were obese and nonobese, and those with and without a family history of diabetes. Associations between sedentary time and diabetes were similar in each subgroup. • It was the first study of sedentary patterns and diabetes in a sample of older adults. Our results consistently showed, using several different metrics for sedentary patterns, that older women with prolonged patterns had higher odds of diabetes than women with interrupted patterns. Similar findings in a cohort of younger adults were reported in relation to diabetes, metabolic syndrome (1) and glycaemic biomarkers (2,3). These key findings are important because it is thought that strategies to change sedentary habits might be more feasible and acceptable than those attempting to increase physical activity or exercise, particularly in older age groups. But the study of sedentary behaviour in relation to diabetes, particularly sedentary patterns, is still very new. It remains unclear how sedentary patterns and the overall amount of time spent sedentary are interrelated. Two other important unanswered questions are 1) can the sedentary patterns of older adults be effectively, feasibly, and acceptably changed? and 2) does changing sedentary patterns improve health and/or protect against chronic illness and mortality? A small pilot study showed how time spent sedentary and patterns of sedentary time might respond differently to intervention (4). When the researchers focused their intervention on reducing participants’ sedentary time, sedentary time reduced and there were no observed changes in the participants’ patterns of sedentary time. Similarly, when the researchers focused on increasing participants’ breaks in sedentary time, patterns of sedentary time were changed but there were no observed changes in their total amount of time spent sedentary. This suggests that multicomponent interventions might be needed to impact both aspects of sedentary behaviour. Larger trials are underway to test the extent to which changing sedentary behaviour habits can impact health (5,6,7). If these larger trials are effective, implementation studies will then be needed to understand what strategies are effective, feasible, acceptable and appropriate in different public health settings (e.g., general community, retirement communities, skilled nursing facilities). Of course, once the effective, feasible, acceptable and appropriate strategies to improve sedentary habits are understood, they will need to be incorporated along with interventions to improve dietary intake and to increase overall physical activity. This latter idea is reflected in the American Diabetes Association physical activity recommendations which are reproduced verbatim from the 2016 position statement (8): • All adults, and particularly those with type 2 diabetes, should decrease the amount of time spent in daily sedentary behavior. • Prolonged sitting should be interrupted with bouts of light activity every 30 min for blood glucose benefits, at least in adults with type 2 diabetes. • The above two recommendations are additional to, and not a replacement for, increased structured exercise and incidental movement. Acknowledgements: This KUDOS summary was written with significant help from Matthew Mclaughlin (@HealthTepi), to whom the authors are extremely grateful. References: 1. van der Berg JD, Stehouwer CDA, Bosma H, et al. Associations of total amount and patterns of sedentary behaviour with type 2 diabetes and the metabolic syndrome: The Maastricht Study. Diabetologia. 2016;59(4):709-718. doi: https://doi.org/10.1007/s00125-015-3861-8 2. Diaz KM, Howard VJ, Hutto B, et al. Patterns of sedentary behavior and mortality in U.S. middle-age and older adults: A national cohort study. Ann Intern Med. 2017:(available online). doi: https://doi.org/10.7326/M17-0212 3. Bellettiere J, Winkler EAH, Chastin SFM, et al. Associations of sitting accumulation patterns with cardio-metabolic risk biomarkers in Australian adults. PLoS One. 2017;12(6):e0180119. doi: https://doi.org/10.1371/journal.pone.0180119 4. Kerr J, Takemoto M, Bolling K, Atkin A, Carlson J, et al. (2016) Two-Arm Randomized Pilot Intervention Trial to Decrease Sitting Time and Increase Sit-To-Stand Transitions in Working and Non-Working Older Adults. PLOS ONE 11(1): e0145427. https://doi.org/10.1371/journal.pone.0145427 5. Trial to Reduce Sitting Time in Postmenopausal Latina Women at Increased Risk for Heart Disease. Link: https://clinicaltrials.gov/ct2/show/NCT02905929?term=jacqueline+kerr&rank=1 6. Sedentary Behavior Interrupted Randomized Controlled Trial (P2). Link: https://clinicaltrials.gov/ct2/show/NCT03473145?term=jacqueline+kerr&rank=5 7. Women's Health Initiative Strong and Healthy Study (WHISH). Link: https://clinicaltrials.gov/ct2/show/NCT02425345?term=andrea+lacroix&rank=2 8. Colberg SR, Sigal RJ, Yardley JE, et al. Physical activity/exercise and diabetes: A position statement of the American Diabetes Association. Diabetes Care. 2016;39(11):2065-2079. doi: https://doi.org/10.2337/dc16-1728

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