Abstract
<title>Abstract</title> <p> <bold>Background:</bold> The age-specific associations between type 2 diabetes (T2DM) and vascular complications (VCs) are not fully understood. We aim to explore the associations of early-onset T2DM and diabetic duration with risk of VCs. <bold>Methods:</bold> A total of 88 803 T2DM patients from the Yinzhou Health Information System (YHIS) were included and followed until December 31, 2022. Data on age at diagnosis, T2DM duration, and VCs (including cardiovascular disease [CVD] and microvascular disease [MVD]) were also derived from the YHIS. Cox regression models were used to assess the associations between early-onset T2DM, disease duration, and VCs, with effect modification by age at diagnosis further explored. <bold>Results:</bold> In stage 1, 37 242 and 36 751 participants were included for CVD and MVD analyses, with 4 136 CVD and 5 029 MVD cases, and median follow-up periods of 8.63 and 8.56 years, respectively. Hazard ratios (HRs) and 95% confidence intervals (CIs)for CVD and MVD in the early-onset group were 1.26 (1.08, 1.47) and 1.73 (1.54, 1.95), respectively. In stage 2, 82 370 and 84 792 participants were included, with 15 677 CVD and 10 949 MVD cases over 8.51 and 8.16 years. Age at diagnosis modified the association between diabetic duration and VCs, with stronger associations in the early-onset group (CVD: HR=1.56, 95% CI: 1.40, 1.73; MVD: HR=1.56, 95% CI: 1.50, 1.68). <bold>Conclusions:</bold> Early-onset type 2 diabetes is associated with a significantly higher risk of VCs, with a higher lifetime risk that is not solely attributable to longer disease duration but is further amplified by the early onset age itself. </p>