The impact of age of onset type 2 diabetes mellitus on risk of cardiovascular disease and mortality, and medical cost: A retrospective cohort study

Abstract

Introduction: Amid the rising incidence with decreasing age of onset, only limited studies have evaluated the effects of age of onset of T2DM on risk of cardiovascular disease (CVD) and mortality, and medical cost against people without T2DM. Methods: A cohort of 170,389 newly-diagnosed T2DM patients with 3,248,907 age-matched non-DM controls were formed from Hong Kong Hospital Authority’s record between 2008-2013, which was then stratified into six groups based on age at baseline (18-39; 40-49; 50-59; 60-69; 70-79; ≥80). Multivariable Cox regression evaluated the association between T2DM and risk of CVD and mortality across age. The effect of age of onset on the medical cost was evaluated by log-linked Gamma generalized linear model. Results: After 9.5 median follow-up years (around 30 million person-years), a total of 211,305 CVD events and 258,268 mortality were recorded. T2DM was associated with increased CVD and mortality risk, but the risks decreased with age. The hazard ratio (95% CI) for CVD associated with T2DM onset at the age 18-39 was 3.57 (2.94-4.33), which was much higher than the risk associated with T2DM onset at age 60-69 (HR: 1.11 (1.08-1.14)) and at age ≥80 (HR: 1.02 (0.98-1.06)). Similarly, the risk of mortality among young onset of T2DM with age at 18-39 (HR: 2.17 (1.80-2.63)) were higher than those with age 60-69 (HR: 1.14 (1.11-1.18)) and age ≥80 (HR: 1.08 (1.05-1.11)). The risk ratio (95% CI) of annual direct medical cost for T2DM onset at age 18-39 relative to the control group (3.50 (3.01-4.06)) was much higher than those for a later onset, such as at age 60-69 (1.31 (1.26-1.35)) and at age ≥80 (1.35 (1.30-1.40)). Conclusions: Young age of onset of T2DM is associated with great impacts on cardiovascular health later in life. This highlights the urge for stringent control of risk factors to prevent T2DM in young adults.