Objective To examine the risk of diabetes mellitus (DM) among subjects with rheumatoid arthritis (RA), psoriatic arthritis or psoriasis (PsA/PsO), compared with non-rheumatic controls.
Methods Study cohorts were assembled using linked healthcare utilisation data from British Columbia. All people with at least two diagnoses of RA or PsA/PsO were included and compared with a cohort of people without any known rheumatic disease. The outcome of interest was a diagnosis of new-onset DM, as defined by initiation of an antidiabetic drug. Incidence rates (IRs) per 1000 person-years and IR ratios were calculated and Cox regression models were constructed to determine the hazard ratio (HR) for diabetes by age, gender, systemic immunosuppressive drug and glucocorticoid use.
Results The study cohort comprised 48 718 subjects with RA, 40 346 with PsA/PsO and 442 033 without any rheumatic disease. The IR for DM among subjects with RA was 8.6 per 1000 person-years (95% CI 8.5 to 8.7), PsA/PsO 8.2 (95% CI 8.1 to 8.3) and for non-rheumatic controls 5.8 (95% CI 5.8 to 5.8). The adjusted HR for RA compared with non-rheumatic controls was 1.5 (95% CI 1.4 to 1.5) and 1.4 (95% CI 1.3 to 1.5) for PsA/PsO.
Conclusions RA and PsA/PsO appear to be associated with an increased risk of DM. The ability of potent antirheumatic treatments to reverse this trend warrants study.
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Funding Amgen supported this work through a research grant to Brigham and Women's Hospital. DHS is also supported by grants from the NIH (NIAMS K24 AR055989, NIAMS P60 AR 047782, NIDCR R21 DE 018750, NIAMS R01 AR 056215), the Arthritis Foundation and AHRQ.
Competing interest None.
Ethics approval This study was conducted with the approval of the Partners Healthcare Human Ethics Committee.
Provenance and peer review Not commissioned; externally peer reviewed.