The Association between Sleep Quality and Type Two Diabetes at 20 Year Follow-up in the Southall And Brent REvisited (SABRE) Cohort: a Tri-ethnic Analysis

Objective The risk of developing type 2 diabetes associated with poor sleep quality is comparable to that of traditional risk factors (e.g. overweight, physical inactivity). In the United Kingdom, these traditional risk factors could not explain the two to three-fold excess risks in South Asian and African Caribbean men compared to Europeans. This study investigates the (i)the association between mid-life sleep quality and later-life type 2 diabetes risk and (ii)a potential modifying effect of ethnicity. Research Design and Methods The Southall and Brent REvisited (SABRE) cohort comprised Europeans, South Asians, and African Caribbeans (median follow-up = 19 years). Complete case analysis was performed on 2190 participants without diabetes at baseline (age= 51.7± 7SD). Competing risks regressions were used to estimate the hazard ratios (HRs) of developing type 2 diabetes associated with four self-reported baseline sleep exposures (difficulty falling asleep, early morning waking, waking up tired and snoring) while adjusting for confounders. Modifying effects of ethnicity were analysed by (i) testing for interactions and (ii) performing ethnicity-stratified analysis. Results Snoring was strongly associated with increased type 2 diabetes risk but only among South Asians in a fully-adjusted model (HR 1.42, 95%CI=1.08-1.85, P=0.011). Our results revealed no elevated risk for any of the sleep exposures across all three ethnic groups. Conclusions The association between snoring and type 2 diabetes appeared to be modified by ethnicity, with South Asians at greatest risk. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement SABRE was funded at baseline by the UK Medical Research Council and Diabetes UK. Follow-up studies have been funded by the Wellcome Trust (WT 082464), British Heart Foundation (SP/07/001/23603 and CS/13/1/30327) and Diabetes UK (13/0004774). NC received support from the National Institute for Health Research University College London Hospitals Biomedical Research Centre. Support has also been provided at follow-up by the North and West London and Central and East London National Institute of Health Research Clinical Research Networks. This present study is entirely independent of the funding bodies, who played no role in these analyses or in the decision to submit the manuscript for publication. VG is funded by a joint grant from the British Heart Foundation and Diabetes UK (15/0005250). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: This current study consisted of secondary data analysis. No primary data was collected. Participants of the SABRE cohort gave informed consent. The baseline study was approved by Ealing, Hounslow and Spelthorne, Parkside, and University College London research ethics committees. The follow-up study was approved by St. Mary's Hospital Local Research Ethics Committee (reference 07/HO712/109). All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes The dataset analysed are available from the SABRE Study Group but restrictions apply to the availability of these data, which were used with permission for the current study, and so are not publicly available. Data are however available from the corresponding author upon reasonable request and with permission from the SABRE Study Group.