Incidence of schizophrenia in a nationwide cohort of patients with type 1 diabetes mellitus.
BACKGROUND
Patients with schizophrenia have an increased risk of type 2 diabetes mellitus. However, very few studies have dealt with the association of type 1 diabetes and schizophrenia. Preliminary evidence points to a possible inverse association.


OBJECTIVE
To investigate the incidence of schizophrenia in a nationwide cohort of patients with type 1 diabetes born in 1950 through 1959 in Finland.


METHODS
A cohort study of individuals born in 1950 through 1959 with a follow-up of 1969 through 1991.


METHODS
Finland.


METHODS
All individuals born in 1950 through 1959 with type 1 diabetes were identified through nationwide registers. The incidence of schizophrenia until 1992 among the total 1950-1959 cohort and in individuals with type 1 diabetes was calculated using information from 3 health care registers.


METHODS
Incidence of schizophrenia.


RESULTS
The incidence of schizophrenia was 0.21 per 10 000 person-years in the group with type 1 diabetes and 0.56 per 10 000 person-years in the group without type 1 diabetes (P < .001).


CONCLUSIONS
The incidence of schizophrenia is decreased in patients with type 1 diabetes.
Juvonen
Hannu
H
Department of Mental Health and Alcohol Research, National Public Health Institute, Mannerheimintie 166, 00300 Helsinki, Finland. hannu.juvonen@ktl.fi
Reunanen
Antti
A
Haukka
Jari
J
Muhonen
Maria
M
Suvisaari
Jaana
J
Arajärvi
Ritva
R
Partonen
Timo
T
Lönnqvist
Jouko
J
D017668:Age of Onset; D000368:Aged; D015331:Cohort Studies; D015897:Comorbidity; D003922:Diabetes Mellitus, Type 1 / Q000453:epidemiology*; D005260:Female; D005387:Finland / Q000453:epidemiology; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012042:Registries / Q000706:statistics & numerical data; D012306:Risk; D012559:Schizophrenia / Q000453:epidemiology*; D017678:Sex Distribution