Temporal trends in macrovascular complications in young-onset diabetes in Korea: A nationwide population-based study.

AIMS: To examine temporal trends and risk factors for macrovascular complications in individuals with young-onset diabetes. METHODS: Data from the Korean Health Insurance Review and Assessment Service (2008-2021) were analyzed for individuals diagnosed with diabetes before age 30 years. Age-standardized incidence and prevalence were estimated using Poisson regression. Time-dependent Cox models assessed risk factors, and segmented regression evaluated changes during the COVID-19 pandemic. RESULTS: We included 6,432 individuals with type 1 diabetes and 71,615 with type 2 diabetes. Between 2008 and 2021, the incidence of macrovascular complications declined from 72.1 to 35.5 per 10,000 persons in type 1 diabetes and from 169.5 to 71.4 in type 2 diabetes, whereas prevalence remained substantial. In type 1 diabetes, older age at diagnosis, low socioeconomic status, hypertension, dyslipidemia, and comorbidity burden increased risk; in type 2 diabetes, older age at diagnosis, low socioeconomic status, hypertension, mental and thyroid disorders, and comorbidity burden increased risk. During COVID-19, incidence increased only in type 2 diabetes. CONCLUSIONS: Despite declining incidence, macrovascular complications remain a substantial burden in young-onset diabetes, particularly in early adulthood and type 2 diabetes, highlighting the need for early cardiovascular risk management.