Prevalence of Diabetes Mellitus in Biopsy-Positive Giant Cell Arteritis

Background: We tested the hypothesis that patients with diabetes mellitus (DM) develop biopsy-positive giant cell arteritis (GCA) significantly less frequently than nondiabetic patients. Methods: We compared the prevalence of DM in patients with positive temporal artery biopsy (TAB) with that in patients with negative TAB via a retrospective study of 215 patients who underwent TAB. Patients were classified as having biopsy-positive GCA if microscopic examination disclosed active or healed arteritis. Patients were classified as having DM if they had a diagnosis of diabetes in their medical history or were taking oral hypoglycemic medications and/or insulin at or before the time of biopsy. In addition, we performed a meta-analysis of 8 previously published articles with a total of 1,401 additional biopsy-proven cases of GCA in patients whose status was recorded as diabetic or nondiabetic. Results: Of 44 cases with biopsy-positive GCA in our patient cohort, only 4 (9.1%) were diabetic at or before the time of biopsy. Of 171 patients with negative TAB, 61 (35.7%) had DM (P = 0.0006). The prevalence of DM among recorded cases of biopsy-positive GCA ranged from 0% to 13.8% in the 8 studies included in our meta-analysis, with a combined frequency of 89 diabetic patients in a total of 1,401 cases (6.35%). Conclusion: The low frequency of a positive TAB in diabetic GCA suspects should be considered when formulating an index of suspicion in the evaluation of patients with possible GCA. More research is needed to delineate the nature of the interaction between DM and GCA.