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The rationale and design of a cross-sectional study to investigate and describe the Chronotype of Patients with Type 2 Diabetes and the Effect on Glycaemic Control: The CODEC study

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posted on 14.10.2019, 10:51 by E Brady, A Hall, E Baldry, S Chatterjee, L Daniels, C Edwardson, K Khunti, M Patel, J Henson, A Rowlands, A Smith, T Yates, M Davies
Introduction A person’s chronotype is their entrained preference for sleep time within the 24-hour clock. It is described by the well-known concept of the ‘lark’ (early riser) and ‘owl’ (late sleeper). Evidence suggests that the ‘owl’ is metabolically disadvantaged due to the standard organisation of our society which favours the ‘lark’ and places physiological stresses on this chronotype. The aim of this study is to explore cardiometabolic health between the lark and owl in a population with an established metabolic condition - Type 2 Diabetes. Methods This cross-sectional, multi-site study aims to recruit 2247 participants from both secondary and primary care settings. The primary objective is to compare glycaemic control between late and early chronotypes. Secondary objectives include determining if late-chronotype is associated with poorer cardiometabolic health and other lifestyle factors, including well-being, compared to early-chronotype; describing the prevalence of the five different chronotypes in this cohort and examining the trends in glycaemic control, cardiometabolic health, well-being and lifestyle factors across chronotype. Analysis The primary outcome (HbA1c), linear regression analysis will compare HbA1c between early and late chronotypes, with and without adjustment for confounding variables. Chronotype will be modelled as a categorical variable with all five levels (from extreme-morning to extremelate type), and as a continuous variable to calculate p for trend across the five categories. A number of models will be created; unadjusted through to adjusted with age, sex, ethnicity, BMI, duration of diabetes, family history of diabetes, current medication and dietary habits. All secondary outcomes will be analysed using the same method. Ethics Ethical approval from the West Midlands - Black Country Research Ethics Committee (16/WM/0457). Dissemination The results will be disseminated through publication in peer reviewed medical journal, relevant medical/health conferences and a summary report sent to patients. Registration details Registered on clinicaltrials.gov NCT02973412 (23.11.20116)


This work was supported by the Lifestyle theme of the National Institute of Health Research (NIHR) Leicester Biomedical Research Centre (BRC).



BMJ Open 2019;9:e027773. doi: 10.1136/bmjopen-2018-027773

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The data collected to date is unpublished therefore not available within the public domain. The research team can access this data. Once primary and secondary analysis have been completed dataset can be requested through the corresponding author.;The file associated with this record is under embargo until publication, in accordance with the publisher's self-archiving policy. The full text may be available through the publisher links provided above.