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Physical behaviors and their association with type 2 diabetes mellitus risk markers in urban South African middle-aged adults: an isotemporal substitutionapproach.

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Peer-reviewed

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Article

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Authors

Goedecke, Julia H 
Masemola, Maphoko 
Chikowore, Tinashe 
Soboyisi, Melikhaya 

Abstract

INTRODUCTION: To examine the associations between physical behaviors and type 2 diabetes mellitus (T2DM) risk markers in middle-aged South African men and women. RESEARCH DESIGN AND METHODS: This cross-sectional study included middle-aged men (n=403; age: median (IQR), 53.0 (47.8-58.8) years) and women (n=324; 53.4 (49.1-58.1) years) from Soweto, South Africa. Total movement volume (average movement in milli-g) and time (minutes/day) spent in different physical behaviors, including awake sitting/lying, standing, light intensity physical activity (LPA) and moderate-to-vigorous intensity physical activity (MVPA), were determined by combining the signals from two triaxial accelerometers worn simultaneously on the hip and thigh. All participants completed an oral glucose tolerance test, from which indicators of diabetes risk were derived. Associations between physical behaviors and T2DM risk were adjusted for sociodemographic factors and body composition. RESULTS: Total movement volume was inversely associated with measures of fasting and 2-hour glucose and directly associated with insulin sensitivity, basal insulin clearance, and beta-cell function, but these associations were not independent of fat mass, except for basal insulin clearance in women. In men, replacing 30 min of sitting/lying, standing or LPA with the same amount of MVPA time was associated with 1.2-1.4 mmol/L lower fasting glucose and 12.3-13.4 mgl2/mUmin higher insulin sensitivity. In women, substituting sitting/lying with the same amount of standing time or LPA was associated with 0.5-0.8 mmol/L lower fasting glucose. Substituting 30 min sitting/lying with the same amount of standing time was also associated with 3.2 mgl2/mUmin higher insulin sensitivity, and substituting 30 min of sitting/lying, standing or LPA with the same amount of MVPA time was associated with 0.25-0.29 ng/mIU higher basal insulin clearance in women. CONCLUSION: MVPA is important in reducing T2DM risk in men and women, but LPA appears to be important in women only. Longitudinal and intervention studies warranted to provide more specific PA recommendations.

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Journal Title

BMJ Open Diabetes Res Care

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Journal ISSN

2052-4897
2052-4897

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Publisher

BMJ
Sponsorship
Cambridge University Hospitals NHS Foundation Trust (CUH) (146281)
MRC (MC_UU_00006/4)
The study received funding from the South African Medical Research Council, with funds received from the South African National Department of Health, the Research Councils UK Newton Fund to the University of Cambridge, GSK (Grant no: ES/N013891/1) and the South African National Research Foundation (Grant no: UID:98561) to the University of Witwatersrand. The work of KW, AS and SB were supported by the NIHR Cambridge Biomedical Research Centre (IS-BRC-1215-20014) and the Medical Research Council (MC_UU_12015/3, MC_UU_00006/4). TC is the recipient of a Wellcome Trust International Training Fellow grant (214205/Z/18/Z).