• Written By: Michael Vaphiades, MD

    This retrospective study published electronically in April by the Journal of Neuro-Ophthalmology tested the hypothesis that patients with diabetes mellitus (DM) develop biopsy-positive giant cell arteritis (GCA) significantly less frequently than nondiabetic patients. It found a significantly lower rate of diabetes among biopsy-positive GCA patients than those with negative temporal artery biopsy (TAB).

    The authors are not aware of any previous studies that have sought to determine, as a primary objective, the prevalence of DM among patients with biopsy-positive GCA compared with a control group with negative TAB.

    Subjects were 215 patients with suspected GCA who underwent TAB. There were 44 cases with biopsy-positive GCA, determined by disclosure of active or healed arteritis during microscopic examination. Only four (9.1 percent) of these patients were diabetic at or before the time of biopsy. There were 171 patients with negative TAB, and 61 (35.7 percent) of these patients had DM (P = 0.0006).

    The authors also performed a meta-analysis of eight previously published articles with a total of 1,401 biopsy-proven cases of GCA in patients whose diabetic or nondiabetic status was recorded. The prevalence of DM among biopsy-positive GCA cases in these studies ranged from 0 to 13.8 percent, with a combined frequency of 6.35 percent.

    The authors present several potential mechanisms to explain the interaction between GCA and DM. The first hypothesis is that in individuals with DM, the cytokine profile may be altered in such a way as to preclude the development of GCA or, alternatively, shifted toward a cytokine pattern more likely to result in biopsy-negative disease. Second, T cells of diabetic patients may be less responsive to the inciting antigens presented by the dendritic cells of the arterial adventitia, a process understood to be crucial in the development of GCA. Third is the possibility of decreased activation of dendritic cells in patients with DM.

    The authors conclude that the nature of the interplay between GCA and DM is complex, and more research is needed to delineate this relationship.