U-shaped association between dietary thiamine intake and new-onset diabetes: a nationwide cohort study

Abstract

Summary Background The association between dietary thiamine intake and the risk of diabetes remains unknown. Aim We aimed to evaluate the relation of dietary thiamine intake with new-onset diabetes and examine possible effect modifiers. Design Prospective cohort study. Methods A total of 16 272 participants who were free of diabetes at baseline were enrolled from China Health and Nutrition Survey (CHNS). Dietary nutrients intake information was collected by 3-day dietary recalls in addition to using a 3-day food-weighed method to assess cooking oil and condiment consumption. New-onset diabetes was defined as a fasting blood glucose ≥7.0 mmol/l or a glycated haemoglobin (HbA1c) ≥6.5% (48 mmol/mol) or diagnosed by a physician during the follow-up. Results During a median follow-up duration of 9.0 years, new-onset diabetes occurred in 1101 participants. Overall, the association between dietary thiamine intake and new-onset diabetes followed a U-shape (P for non-linearity <0.001). Consistently, when thiamine intake was assessed as quartiles, compared with those in the 2–3 quartiles (0.75 to 1.10 mg/day), the significantly higher risks of new-onset diabetes were found in participants in the first quartile [adjusted hazard ratio (HR), 1.33; 95% confidence interval (CI): 1.10, 1.61] and the fourth quartile (adjusted HR, 1.39; 95% CI: 1.17, 1.67). Similar results were found when further adjusting for the intake of other major nutrients or food groups; or using the propensity score weighting to control the imbalance of covariates. Conclusion Our results suggested that there was a U-shape association between dietary thiamine intake and new-onset diabetes in general Chinese adults, with a minimal risk at 0.75–1.10 mg/day.