Arterial stiffness in Type 1 diabetes mellitus is aggravated by autoimmune thyroid disease

Objective: The aim of our study was to measure arterial stiffness in patients with Type 1 diabetes mellitus, its contributing factors and its relation to macrovascular arterial changes. Materials and methods: Thirty-one female Type 1 diabetic patients were studied; 11 had concomitant autoimmune thyroid disease although euthyroid during the study period. Stiffness was studied using applanation tonometry and pulse wave analysis for evaluation of systolic arterial pressure augmentation secondary to arterial stiffening and early wave reflection. Results were compared to 24 healthy individuals. In all patients, endothelium-related flow-mediated dilation (FMD) of the brachial artery and intima-media thickness (IMT) of the carotid artery were measured. Results: Augmentation pressure (AP) and augmentation index (AI) were higher in Type 1 diabetic patients suggesting stiffer arteries compared to controls (AP: 5.8±3.6 vs 2.8±2.2 mmHg, p<0.001; and AI:18.3±9 vs 11.1 ±8.8%, p=0.004). The subgroup of diabetic patients with autoimmune thyroid disease presented stiffer arteries than those without (AP: 6.5±2.9 vs 5.5±3.9 mmHg, p<0.05; and AI: 21.3±5.4 vs 16.7±10.3%, p<0.05), though the two groups did not differ statistically by means of age, disease duration, hemoglobin A1c (HbA1c), lipid levels, FMD and IMT. In multiple regression analysis, variables independently associated to AI in the diabetes group were: age (p=0.028), IMT of the carotid artery bifurcation (p=0.045), disease duration (p=0.031) and autoimmune thyroid disease (p=0.015). No correlation was observed between AI and metabolic control, blood pressure, microalbuminuria, presence of retinopathy and endothelial function (FMD). Conclusions: Women with Type 1 diabetes have increased arterial stiffness, which indicates macroangiopathy. An independent correlation between these indices and carotid IMT was observed. Concomitant autoimmune thyroid disease seems to aggravate arterial compliance in these patients, a finding that merits further investigation.