Risk of Diabetes Mellitus among Patients Diagnosed with Giant Cell Arteritis or Granulomatosis with Polyangiitis: Comparison with the General Population.

Abstract

Patients with organ- or life-threatening vasculitis receive high cumulative glucocorticoid (GC) doses during their disease course. GC have diabetogenic effects, but the risk of diabetes mellitus (DM) related to vasculitis therapy is not well characterized. We assessed the DM risk among patients diagnosed with giant cell arteritis (GCA) or granulomatosis with polyangiitis (GPA), i.e., patients with relatively common forms of systemic vasculitis. We used Danish healthcare registries to identify 1682 patients diagnosed with GCA and 342 patients diagnosed with GPA from 1997 to 2015 and to obtain information regarding medication exposures. Each patient with vasculitis was matched with 9 population controls. Date of new-onset DM was defined as date of first claimed prescription for an antidiabetic drug. We used Cox regression analyses to calculate incidence rate ratios (IRR) for DM as a measure of the DM risk among patients relative to population controls. Logistic regression was used to study the association between prednisolone/prednisone (PRED) dose and DM. Median duration of followup was 6.5 years [interquartile range (IQR) 2.6-10.4] in the GCA cohort and 5.8 years (IQR 1.7-10.6) in the GPA cohort. During the first year after diagnosis of vasculitis, the IRR for DM was 7.0 (95% CI 5.2-9.3) among patients with GCA and 10.4 (95% CI 4.4-24) among patients with GPA. IRR for DM were not significantly increased in either cohort during later followup periods. Within the first year, treatment with high cumulative prednisolone/PRED doses was associated with new-onset DM among the patients with vasculitis. Patients diagnosed with GCA or GPA have a markedly increased risk of new-onset DM during early treatment phases.