1013 SHIFT WORK, CHRONOTYPE, AND TYPE 2 DIABETES IN THE UK BIOBANK AND TYPE 2 DIABETES IN THE UK BIOBANK

Abstract

Introduction: Night shift work has been associated with a moderate increased risk for type 2 diabetes (T2D). We had previously reported that this association is chronotype-dependent among women. Our current aim was to probe the link between shift work, chronotype and T2D in a large sample of both men and women. Methods: Of the entire UK Biobank population (N=501,753), we included those who were currently employed, responded to the chronotype question, and free of chronic disease (N=241,512, including 5,982 T2D cases). We used logistic regression to estimate odds ratios (OR) of prevalent T2D and 95% confidence intervals (95%CI) across categories of night shift work and report multi-variable adjusted models, adjusting for age, sex, family history of diabetes, ethnicity, and socio-economic status. Secondary analyses examined whether associations differed by sex, obesity status, and chronotype. Results: Compared to day workers, participants working night shifts were younger, more often male, with a family history of diabetes, and of non-European ethnicity. Age- and sex-adjusted models showed that participants working irregular schedules usually including night shifts had a two-fold higher T2D risk (OR=2.04; 95%CI=1.91-2.67) when compared to day workers. We did not observe evidence for effect modification by obesity status (p=0.47). When we included BMI in multi-variable adjusted models risk estimates were attenuated: compared to day workers, workers with irregular schedules usually including exposure to night shifts had an increased T2D risk (1.41 (1.17-1.68)); shift work without or only rarely including night shifts: (1.14 (1.04-1.24); irregular shifts including some night shifts (1.10 (0.98-1.22)). Permanent night shift work did not increase T2D risk compared to day work (1.06(0.91-1.23)). We did not observe evidence for effect modification by chronotype (p=0.92) or sex (p=0.07). Conclusion: Our results add to the body of literature suggesting a link between irregular and rotating night shift work and T2D risk. Unlike earlier studies where chronotype differentially affected T2D risk depending on chronotype, current exposure status does not seem similarly associated with T2D risk. Future research is warranted to further elucidate the role of shift schedule characteristics and chronotype.