Background The majority of JIA categories are considered as autoimmune diseases. Autoimmune diseases seem to cluster in children and adolescents with JIA, which is attributed to shared susceptibility genes. Studies revealed an increase in the simultaneous JIA and juvenile type 1 diabetes mellitus (T1D) occurrence and an increased JIA prevalence in patients with T1D . However, the frequency of T1D in JIA patients in comparison to the general population is unknown.
Objectives To determine the frequency of T1D in JIA patients and to characterize patients having both JIA and T1D.
Methods Diabetes comorbidity was recorded in the national paediatric rheumatologic database (NPRD) in 2012 and 2013. Data of the North Rhine-Westphalian diabetes register and the Diabetes data acquisition system for prospective surveillance (DPV) served as reference for the diabetes prevalence in the general population. NPRD data were indirectly standardized for age and sex for the comparison with the general population. The diabetes prevalence ratio (PR) was calculated using Poisson regression models.
Results 9,359 JIA patients were included in the analyses. Patient mean age was 12 years (SD 4.5), mean disease duration 4.5 years (SD 3.8). 50 patients had T1D in addition to JIA, diabetes prevalence was 0.5%. Patients with versus without T1D did not differ significantly in the JIA category spectrum. Compared to the general population, the diabetes prevalence in JIA patients was significantly increased (PR: 1.96 [CI: 1.49;2.59], p<0.001). The PR for diabetes for girls was 1.92 (CI: 1.35;2.73, p<0.001) and for boys 2.04 (CI: 1.30;3.19, p=0.002). Diabetes onset in JIA patients was slightly earlier than in the age- and sex-matched population. More than half of the patients (58%) developed diabetes before JIA. Diabetes onset was on average 60 months before the JIA onset. Patients with JIA before T1D developed T1D on average 35 months after JIA onset. The majority of these patients had not received any DMARDs before diabetes onset.
Conclusions Diabetes type 1 occurs more frequently in JIA patients than in the general population. The likelihood of T1D seems to be slightly higher before JIA manifestation and in patients who were not treated with DMARDs after JIA onset.
The NPRD has been funded by the German Children Arthritis Foundation (Deutsche Kinder-Rheumastiftung).
Hermann G, Thon A, Mönkemoller K, Lilienthal E, Klinkert C, Holder M et al. Comorbidity of type 1 diabetes and juvenile idiopathic arthritis. J Pediatr 2015;166:930–5.
Disclosure of Interest None declared