Cause-specific mortality trends in a nationwide population-based cohort of childhood-onset type 1 diabetes in Japan during 35 years of follow-up: the DERI Mortality Study

Aims/hypothesis The aim of this study was to investigate long-term, cause-specific mortality trends among patients with childhood-onset type 1 diabetes in Japan. Methods Individuals included in the study had received a diagnosis of type 1 diabetes at age <18 years between 1965 and 1979. All individuals were followed up for their survival status until 1 January 2005. The causes of death were divided into end-stage renal disease (ESRD), acute diabetic complications (ADC), accident/suicide, cardiovascular disease (CVD), infections, cancers, others (non-diabetic/diabetic) and unknown. The cause-specific mortality trends were expressed according to the follow-up period and year of diagnosis. Results A total of 1,385 patients were enrolled in the study, and the survival status of 1,324 was confirmed. Mortality rate at the 35 year follow-up (per 100,000 person-years) was 659.3, and the standardised mortality ratio (SMR) was 10.7. The SMR at the 25 year follow-up markedly declined from 19.3 in the 1965–1969 diagnosis group to 6.6 in the 1975–1979 diagnosis group. Approximately 40% died of ADC among those with <10 years of follow-up. A similar proportion of individuals died of ESRD among those with 10–19 years of follow-up. The longer the duration of follow-up, the lower the mortality from ADC and the greater the mortality from CVD. Conclusions/interpretation In Japanese people with childhood-onset type 1 diabetes of more than 20 years of duration, CVD was the leading cause of death, as is the case among similar white people. The longer the duration of diabetes, the more attention should be paid to preventing CVD.