Dan Wu ¹ Yang Yu ¹ Haoran Zheng ¹ Ling Xiang ¹ Xiaoqing Wang ¹ Yong Zhang ¹ Zhongming Sun ² Dandan Miao ² Jinyi ZHOU ³ Enchun PAN ^2* Wen Hu ^1*

• ¹ Department of Endocrinology, Huai’an Hospital Affiliated to Xuzhou Medical University and Huai’an Second People’s Hospital, Huai’an 223001, Jiangsu, China
• ² Huaian Center for Disease Control and Prevention, Huai'an, China
• ³ Jiangsu Provincial Center for Disease Control And Prevention, Nanjing, Jiangsu Province, China

Objectives: To examine the association between the age at onset of diabetes and the risk of all-cause mortality in a population of individuals diagnosed with type 2 diabetes mellitus (T2DM) and to identify risk factors associated with all-cause mortality in young-onset T2DM (YOD) patients in China. Methods: This study utilized a cohort of 9759 patients who were diagnosed with T2DM and who were registered and enrolled in the National Basic Public Health Service Management Program in Qinghe District (now Qingjiangpu District) and Huai'an District, Huai'an City, Jiangsu Province, China. The patients were observed from November 2013 to July 2014, and all-cause mortality data were obtained by comprehensive matching with the Huai'an City Resident Mortality Database as of December 31, 2019. A Cox proportional hazards model was used to calculate hazard ratios and 95% confidence intervals for all-cause mortality risk in patients with different disease onset ages. Subgroup analyses were also done based on sex, age, lifestyle factors, and baseline clinical parameters. Results: A total of 7572 patients with T2DM, including 2874 men and 4698 women aged 57.9±8.0 years, were ultimately included in the study. During the six-year follow-up period, a total of 1057 deaths were documented. After adjusting for confounding factors and utilizing SD as the reference group, the HRs for deaths occurring in the YOD and MD groups were 1.383 (95% CI: 0.717-2.667) and 1.006 (95% CI: 0.763-1.326), respectively. Moreover, the risk of death in the YOD group remained highest in the sensitivity analysis that excluded patients with coronary heart disease at baseline, stroke patients, and patients who died within the first three years of follow-up. Sleep duration was identified as an independent risk factor for mortality in the YOD group, with a notable increase in the risk of all-cause mortality when sleep duration exceeded 9 hours per day. Conclusion: The risk of all-cause mortality in YOD patients was 1.38 times greater than that in MD and SD patients, and the longer the sleep duration was, the greater the risk of death, especially when sleep duration exceeded 9 hours per day.