Adult complications of childhood-onset type 1 diabetes vary with age at diagnosis: a population-based study

<jats:p>&lt;p dir="ltr"&gt;Objective: To examine incidence of long-term complications amongst people with childhood-onset type 1 diabetes, focusing on age-of-diabetes-onset.&lt;/p&gt;&lt;p dir="ltr"&gt;Research design and methods: A registry of children diagnosed with type 1 diabetes aged &lt;16 years in New South Wales, Australia, between 1990-2009 linked to hospital, emergency department, public insurance and death data from 2001-2019 to identify complications. Age-of-onset was categorized: &lt;7 years, 7-&lt;13 years, 13-&lt;16 years. Incidence rates and hazard ratios (HR), with 95% confidence intervals (CI), for the risk of complications, were calculated from multivariable Cox regression models by; (1) duration of diabetes 0-&lt;20 years and (2) attained age of 16-34 years, with HR adjusted for diagnosis year, socio-demographics and acute diabetic complications.&lt;/p&gt;&lt;p dir="ltr"&gt;Results: Of 5202 people identified; 1,694 (32.6%) were diagnosed &lt;7 years, 2,538 (48.8%) aged 7-&lt;13, and 970 (18.6%) aged 13-&lt;16. Within 20 years of onset, incidence ranged from 9.2/10,000 person-years (95% CI 7.2, 11.7) for cardiac complications, to 53.4/10,000 person-years (95% CI 48.2, 59.0) for kidney complications. Diabetes onset &lt;7 years (vs 13-&lt;16) was associated with lower 20-year risk of complications, except lower limb infections; cardiac adjusted HR (aHR) 0.32 (95% CI 0.15, 0.66), severe retinopathy aHR 0.25 (0.17, 0.36), lower limb vascular complications aHR 0.41 (0.24, 0.69), peripheral neuropathy aHR 0.16 (0.08, 0.32) and kidney complications aHR 0.40 (0.30, 0.53). Risk of complications did not differ by attained age.&lt;/p&gt;&lt;p dir="ltr"&gt;Conclusion: Children with type 1 diabetes onset &lt;7 years had lower chronic complication risk in first 20-years post-diagnosis, supporting a slower time to develop complications with pre-pubertal onset. &lt;/p&gt;</jats:p>