Eating duration and shift work can both influence metabolic regulation, but their joint associations with diabetes are unknown. We aimed to examine the independent and joint associations of eating duration and shift work with diabetes in a cross-sectional study using a nationally representative sample of US workers. We included 14852 eligible participants from the National Health and Nutrition Examination Survey, 2005–2010 and 2017–2020. Eating duration was calculated based on first and last eating occasions from 24-h dietary recalls. Long eating duration (LED: ≥ 13 h) v. short eating duration (SED: < 13 h) was defined based on the median. Workers were classified as engaging in shift work (SW, n 5140) v. non-shift work (NSW, n 8945) based on self-report. Logistic regressions were used to examine the associations of LED and SW with diabetes, independently and jointly with stratification by age. LED was associated with higher odds of diabetes among workers aged < 45 years (OR, 1·51; 95 % CI, 1·05–2·19) but not among workers aged ≥ 45 years (OR, 0·98; 95 % CI, 0·79–1·20). SW was associated with higher odds of diabetes among both younger (OR, 1·28; 95 % CI, 0·88–1·85) and older workers (OR, 1·28; 95 % CI, 1·04–1·58). There was suggestive evidence that workers with both LED and SW had higher odds of diabetes compared with those with SED and NSW, but the association was stronger among younger (OR, 1·40; 95 % CI, 0·85–2·28) than older workers (OR, 1·28; 95 % CI, 0·99–1·66). LED and SW were independently associated with increased odds of diabetes with suggestive evidence on their joint associations, but associations varied by workers’ age.

The long-term impact of eating duration on the risk of all-cause mortality remains unclear, with limited exploration of how different levels of energy intake and physical activity might influence this impact. To investigate, 24 484 American adults from the National Health and Nutrition Examination Survey spanning 1999–2018 were included. Eating duration was assessed via 24-h dietary recall, and all-cause mortality data were sourced from the National Death Index. The relationship between eating duration and all-cause mortality was analysed using Cox proportional hazards regression models, restricted cubic splines and stratification analysis with complex weighted designs. The median (IQR) of eating duration for participants was 12·5 (11·0, 14·0) h. In this study, 2896 death events were observed, and the median follow-up time (IQR) was 125 (77, 177) months. After multivariable adjustment, compared with Q1, Q2, Q3 and Q4 had reduced risks of all-cause mortality by 17, 15 and 13 %, respectively. Furthermore, each additional hour of eating duration was correlated with a 2 % decrease in the risk of all-cause mortality. Additionally, a non-linear dose–response relationship was observed between eating duration and the risk of all-cause mortality, showing a U-shaped relationship from 8·9 h to 15·3 h (P for non-linearity < 0·05). Interestingly, the non-linear dose–response relationship was observed exclusively among individuals with high energy intake or a lightly active physical activity level. These findings suggest potential health benefits from adjusting eating duration, though further prospective studies are needed for validation.