In this cohort, we investigated
the mortality rate and standardized mortality ratio (SMR) among all patients
who developed type 1 diabetes at age <15 years from 1959 to 1996 in Hokkaido
Prefecture, Japan. Out of 521 enrolled patients, we analyzed the data of 391
whose attending physicians replied to our survey. Mortality rates per 100,000
person-years and SMRs were 475 and 6.9 for all patients, 559 and 8.5 for men,
and 424 and 6.0 for women, respectively. For the time of onset of type 1
diabetes, these variables were 823 and 8.8 between 1959 and 1979, 370 and 5.9
between 1980 and 1989, and 133 and 3.2 between 1990 and 1996, respectively. Mortality
rates per 100,000 person-years and SMRs were 452 and 7.3 for onset before
puberty and 514 and 6.3 for onset after puberty, respectively, and 480 and 7.1
for the acute-onset subtype and 428 and 5.6 for the incidentally detected
non-acute-onset subtype, respectively. Upon survival analysis, we observed no
difference in mortality or lifespan between the sexes. Mortality and lifespan
were not different between pre- and postpubertal onset and did not differ
between the subtypes of type 1 diabetes.