This study aimed to evaluate the association between type 2 diabetes mellitus (T2DM) onset age and risk of cardiovascular disease (CVD) and mortality.

Two retrospective cohort studies were conducted using the electronic health records from the United Kingdom (UK) and Hong Kong (HK) on adults without CVD. During 2008-2013, 128,918 and 185,646 patients with new-onset T2DM were assigned to the T2DM group, and 5,052,770 and 3,159,396 patients without T2DM were included as controls in the UK and HK cohort, respectively. Patients were stratified into six age groups. Multivariable Cox regression, adjusted for baseline characteristics and fine stratification weights, was used to estimate the hazard ratios (HRs) and 95 % confidence intervals (CIs) for each outcome.

New-onset T2DM was associated with increased CVD and mortality risk, but the risks decreased with age. Compared to those without T2DM in the same age groups, the HR (95 % CI) for CVD in the UK cohort was 3.22 (2.80, 3.71), 1.21 (1.15, 1.26), and 0.99 (0.93, 1.05) for T2DM individuals at ages 18–39, 60–69, and ≥ 80, respectively. Similarly, the HR (95 % CI) for mortality among new-onset T2DM patients was 2.41 (2.06, 2.83) for age 18–39, 1.40 (1.34, 1.46) for age 60–69, and 1.12 (1.08, 1.16) for age ≥ 80. Results from the HK cohort showed a similar pattern.

Young onset of T2DM is associated with a significant impact on cardiovascular health later in life. This highlights the importance of the prevention of DM in young adults.