Incidence of Giant Cell Arteritis: Diabetes Mellitus is Not Protective

Previous reports suggest a protective effect of diabetes mellitus (DM) against giant cell arteritis (GCA). One recent retrospective study found a lower prevalence of diabetes among patients with a positive temporal artery biopsy (TAB) than with a negative TAB. A meta-analysis of 8 studies found a low prevalence of biopsy positive GCA among diabetics. The authors suggested that DM may lower the risk of GCA. To our knowledge, the effect of DM on GCA has not been studied prospectively. Using the Medicare database, we followed historical patients prospectively through time to compare the incidence of GCA among patients with and without diabetes.