Cause-Specific Mortality Trends in a Large Population-Based Cohort With Long-Standing Childhood-Onset Type 1 Diabetes

Abstract

OBJECTIVE Little is known concerning the primary cause(s) of mortality in type 1 diabetes responsible for the excess mortality seen in this population. RESEARCH DESIGN AND METHODS The Allegheny County (Pennsylvania) childhood-onset (age <18 years) type 1 diabetes registry (n = 1,075) with diagnosis from 1965 to 1979 was used to explore patterns in cause-specific mortality. Cause of death was determined by a mortality classification committee of at least three physician epidemiologists, based on the death certificate and additional records surrounding the death. RESULTS Vital status for 1,043 (97%) participants was ascertained as of 1 January 2008, revealing 279 (26.0%) deaths overall (141 females and 138 males). Within the first 10 years after diagnosis, the leading cause of death was acute diabetes complications (73.6%), while during the next 10 years, deaths were nearly evenly attributed to acute (15%), cardiovascular (22%), renal (20%), or infectious (18%) causes. After 20 years' duration, chronic diabetes complications (cardiovascular, renal, or infectious) accounted for >70% of all deaths, with cardiovascular disease as the leading cause of death (40%). Women (P < 0.05) and African Americans (P < 0.001) have significantly higher diabetes-related mortality rates than men and Caucasians, respectively. Standardized mortality ratios (SMRs) for non–diabetes-related causes do not significantly differ from the general population (violent deaths: SMR 1.2, 95% CI 0.6–1.8; cancer: SMR 1.2, 0.5–2.0). CONCLUSIONS The excess mortality seen in type 1 diabetes is almost entirely related to diabetes and its comorbidities but varies by duration of diabetes and particularly affects women and African Americans.