OBJECTIVE To investigate the occurrence of suicide in men with insulin-dependent diabetes mellitus (IDDM).

RESEARCH DESIGN AND METHODS A cohort of all Danish men born between 1949 and 1964 (including 1964) who were diagnosed with IDDM before age 20 (n = 1,682) was ascertained earlier. Follow-up from diagnosis to death or 1 January 1991 was based on record linkage with the Danish Civil Registration System and was supplemented with information from death certificates obtained from the Danish National Registry of Deaths. From published vital statistics, cause-specific standardized mortality ratios (SMRs), adjusted for age and calendar time, were calculated.

RESULTS Among the 168 deaths recorded during follow-up, 15 took place in connection with the onset of IDDM and have been excluded. Of the remaining 153 deaths, 12 were officially classified as suicides (SMR 12/7.48 = 1.6, 0.05 < P < 0.1); as for the age-group of 20-24 years, SMR was 2.98, P < 0.05. Furthermore, all deaths officially classified as attributable to unknown causes (n = 28) and accidents (n = 22) were reviewed with respect to unrecognized suicides; as for deaths of unknown causes, three could be reclassified as probable suicides and two as possible suicides, whereas one of the deaths caused by accident could be reclassified as possible suicide.

CONCLUSIONS Young men with IDDM may confer a higher risk of suicide than expected. Furthermore, suicide may represent an underestimated cause of death among patients with IDDM.