Objective.To describe the occurrence and main clinical and laboratory findings of patients having both juvenile idiopathic arthritis (JIA) and diabetes mellitus type 1 (DM-1) in a period of 30 years.Methods.Eighty-two patients having simultaneous JIA and DM-1 were identified in the reimbursement registers of the Finnish National Institute of Insurance during the period 1976–2005. Data on their clinical histories were collected from patient files.Results.Occurrence of simultaneous JIA and DM-1 increased 4.5-fold between the first (1976-85) and the last (1996–2005) decade. Prevalence of uveitis was 7%, of rheumatoid factor seropositivity 15%; 22% of patients had a third autoimmune disease [autoimmune disease (AID)], and 16% had serious psychiatric problems.Conclusion.The occurrence of patients with the 2 diseases, JIA and DM-1, increased over 3 decades. The prevalence of uveitis was low, the number of seropositive patients was high, and further cases of AID were frequent. Patients had multiple additional problems necessitating multiprofessional care.
