A Study of the Vascular Endothelial Function in Patients with Type 2 Diabetes Mellitus and Rheumatoid Arthritis

Objective Type 2 diabetes mellitus (T2DM) and rheumatoid arthritis (RA) are both complicated by arteriosclerosis, resulting in increased rates of cardiovascular events. No previous studies have compared the index between RA and T2DM. We assessed the vascular endothelial function in early-stage arteriosclerosis for each disease to determine the influential factors and compared the extent to which these two diseases cause vascular endothelial dysfunction. Methods This study is a retrospective study based on medical records. Differences in the reactive hyperemia index (RHI) among the groups and factors affecting the RHI in each group was analyzed. The vascular endothelial function was assessed by measuring the RHI using peripheral arterial tonometry. Patients The study subjects were 114 patients with non-functional thyroid tumors (healthy n=14), T2DM (T2DM n=64), and RA (RA n=36). Results The RHI was 2.29 in the control, 1.85 in the T2DM, and 1.83 in the RA group, with values lower in the T2DM and RA groups than in the control group (p=0.033) but not markedly different between the two disease groups. The RHI distribution (<1.68/1.68 to <2.10/≥2.1) was as follows: control group: 14.3%/28.6%/57.1%; T2DM group: 42.2%/39.1%/18.8%; and RA group: 36.1%/44.4%/19.4% (p=0.031), respectively. A multivariate analysis identified the triglyceride level and dyslipidemia in the control group and the Disease Activity Score in 28 joints with the erythrocyte sedimentation rate and fasting plasma glucose level in the RA group to influence the RHI. Conclusion The vascular endothelial function was impaired in approximately 80% of patients with T2DM and RA, with comparable degrees of impairment between the two diseases. No factors affecting the function were identified in the T2DM group, while the function was more impaired in patients with a higher disease activity in the RA group.