Adult Complications of Childhood-Onset Type 1 Diabetes Vary With Age at Diagnosis: A Population-Based Study.

OBJECTIVE: To examine incidence of long-term complications among people with childhood-onset type 1 diabetes, focusing on age at diabetes onset. RESEARCH DESIGN AND METHODS: A registry of children diagnosed with type 1 diabetes aged <16 years in New South Wales, Australia, between 1990 and 2009 linked to hospital, emergency department, public insurance, and death data from 2001 to 2019 to identify complications. Age at onset was categorized as <7 years, 7 to <13 years, and 13 to <16 years. Incidence rates and hazard ratios (HR), with 95% CI, for the risk of complications, were calculated from multivariable Cox regression models by 1) duration of diabetes 0 to <20 years and 2) attained age of 16-34 years, with HR adjusted for diagnosis year, sociodemographics, and acute diabetes complications. RESULTS: Of 5,202 people identified, 1,694 (32.6%) were diagnosed at age <7 years, 2,538 (48.8%) age 7 to <13 years, and 970 (18.6%) age 13 to <16 years. Within 20 years of onset, incidence ranged from 9.2 per 10,000 person-years (95% CI 7.2, 11.7) for cardiac complications to 53.4 per 10,000 person-years (95% CI 48.2, 59.0) for kidney complications. Diabetes onset at age <7 years (vs. 13 to <16 years) was associated with lower 20-year risk of complications, except lower-limb infections; cardiac adjusted HR (aHR) was 0.32 (95% CI 0.15, 0.66), severe retinopathy aHR was 0.25 (0.17, 0.36), lower-limb vascular complications aHR was 0.41 (0.24, 0.69), peripheral neuropathy aHR was 0.16 (0.08, 0.32), and kidney complications aHR was 0.40 (0.30, 0.53). Risk of complications did not differ by attained age. CONCLUSIONS: Children with type 1 diabetes onset at age <7 years had lower chronic complication risk in the first 20 years postdiagnosis, supporting a slower time to develop complications with prepubertal onset.