Patients with newly diagnosed rheumatoid arthritis are at increased risk of diabetes mellitus: an observational cohort study.

Aims: To reveal the prevalence of Diabetes Mellitus (DM) in patients with newly diagnosed Rheumatoid Arthritis (RA) and evaluate the association between clinical characteristics of RA and DM as well as treatment response in newly diagnosed RA patients with DM. Methods: Newly diagnosed, adult, RA patients, who were registered in Danish Danbio since 1st January 2010, were included. Patients’ demographics, serology results including rheumatoid factor (RF), anti-cyclic citrullinated peptide antibody (anti-CCP) and antinuclear antibody (ANA) as well as disease activity score in 28 joints-C-reactive protein (DAS28-CRP) at the time of diagnosis and after 4 months (±1-2 months) of treatment initiation were extracted from Danbio Registry. To reveal the presence of DM, patients’ electronic medical records were reviewed. The prevalence of DM in our patients was compared (using an age- and gender-matched analysis) with that expected from Danish population. Results: of 439 included patients, 60.1% were female, mean of age 64.6±15.0 years and RA disease duration 2.6±1.7 years. Prevalence of DM was 57/439 (12.9%), herein type II DM 52 (91.2%) and type I DM 5 (8.8%). Except for two patients, diagnosis of DM was established prior to the diagnosis of RA. The prevalence of DM in newly diagnosed RA patients of all ages was significantly increased versus that expected from Danish population (RR=2.21, CI=1.40-3.42, P min 0.001). In addition, prevalence of DM was significantly increased with more than twice of the expected for RA patients aged 65-84. Both genders showed increased risk of DM after subgroup analysis. The presence of DM in RA patients was significantly associated with age (P min 0.001) and RA disease duration ≥4 years (P =0.05). We did not find any significant associations between presence of DM and gender, RF, anti-CCP as well as ANA. Additionally, presence of DM in the RA patients was not a negative predictor of treatment response measured by the European League Against Rheumatism (EULAR) response criteria and ∆DAS28-CRP. Conclusion: Newly diagnosed RA patients are at higher risk of DM (13% versus 5.7% in Denmark), and a high index of suspicion must be kept.