Association of change in daily step count over five years with insulin sensitivity and adiposity: population based cohort studyBMJ 2011; 342 doi: https://doi.org/10.1136/bmj.c7249 (Published 13 January 2011) Cite this as: BMJ 2011;342:c7249
- T Dwyer, director12,
- A-L Ponsonby, group leader12,
- O C Ukoumunne, senior research fellow1,
- A Pezic, research assistant1,
- A Venn, deputy director2,
- D Dunstan, research fellow3,
- E Barr, epidemiologist3,
- S Blair, professor4,
- J Cochrane, data manager2,
- P Zimmet, professor3,
- J Shaw, associate director3
- 1Murdoch Children’s Research Institute, Royal Children’s Hospital, Parkville, Melbourne 3052, Australia
- 2Menzies Research Institute, University of Tasmania, Hobart 7000, Australia
- 3Baker IDI Heart and Diabetes Institute, Melbourne 3004, Australia
- 4Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, USA
- Correspondence to: T Dwyer
- Accepted 12 October 2010
Objectives To investigate the association between change in daily step count and both adiposity and insulin sensitivity and the extent to which the association between change in daily step count and insulin sensitivity may be mediated by adiposity.
Design Population based cohort study.
Setting Tasmania, Australia.
Participants 592 adults (men (n=267), mean age 51.4 (SD 12.2) years; women (n=325), mean age 50.3 (12.3) years) who participated in the Tasmanian component of the national AusDiab Study in 2000 and 2005.
Main outcome measures Body mass index, waist to hip ratio, and HOMA insulin sensitivity at follow-up in 2005.
Results Over the five year period, the daily step count decreased for 65% (n=382) of participants. Having a higher daily step count in 2005 than in 2000 was independently associated with lower body mass index (0.08 (95% confidence interval 0.04 to 0.12) lower per 1000 steps), lower waist to hip ratio (0.15 (0.07 to 0.23) lower), and greater insulin sensitivity (1.38 (0.14 to 2.63) HOMA units higher) in 2005. The mean increase in HOMA units fell to 0.34 (−0.79 to 1.47) after adjustment for body mass index in 2005.
Conclusions Among community dwelling, middle aged adults, a higher daily step count at five year follow-up than at baseline was associated with better insulin sensitivity. This effect seems to be largely mediated through lower adiposity.
We thank the AusDiab study participants and all staff involved in the fieldwork of this study.
Contributors: TD, AV, JS, DD, EB, SB, and PZ contributed to the conception and design of the study. TD, AV, EB, and JC contributed to the conduct of the study. TD, A-LP, OCU, AP, and JC contributed to the analysis and interpretation of data. TD, A-LP, OCU, and AP contributed to drafting the article. All authors contributed to revising the article critically for important intellectual content and approved the final version. TD the is guarantor.
Funding: The study received financial support from the Commonwealth Department of Health and Aged Care, Abbott Australasia, Alphapharm, Aventis Pharmaceutical, AstraZeneca, Bristol-Myers Squibb Pharmaceuticals, Eli Lilly (Australia), GlaxoSmithKline, Janssen-Cilag (Australia), Merck Lipha, Merck Sharp & Dohme (Australia), Novartis Pharmaceutical (Australia), Novo Nordisk Pharmaceutical, Pharmacia and Upjohn, Pfizer, Roche Diagnostics, Sanofi Synthelabo (Australia), Servier Laboratories (Australia), BioRad Laboratories, HITECH Pathology, the Australian Kidney Foundation, Diabetes Australia, Diabetes Australia (Northern Territory), Queensland Health, South Australian Department of Human Services, Tasmanian Department of Health and Human Services, Territory Health Services, Victorian Department of Human Services, and Health Department of Western Australia. DD is supported by a Victorian Health Promotion Foundation public health research fellowship. OCU is supported by NHMRC Population Health Capacity Building Grant 436914. JS is supported by an NHMRC senior research fellowship.
Competing interests: All authors have completed the Unified Competing Interest form at www.icmje.org/coi_disclosure.pdf (available on request from the corresponding author) and declare that all authors had: (1) No financial support for the submitted work from anyone other than their employer; (2) No financial relationships with commercial entities that might have an interest in the submitted work; (3) No spouses, partners, or children with relationships with commercial entities that might have an interest in the submitted work; (4) No Non-financial interests that may be relevant to the submitted work.
Ethical approval: The International Diabetes Institute Ethics Committee and the Human Research Ethics Committee of the University of Tasmania approved this study. All participants gave their consent by signing a consent form.
Data sharing: No additional data available.
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