Relationship between subclinical hypothyroidism and endothelial dysfunction in patients with type 2 diabetes: A cross-sectional study

Abstract

Purpose: To investigate the relationship between subclinical hypothyroidism (SCH) and vascular endothelial function in patients with type 2 diabetes mellitus (T2DM). Methods: The reactive hyperemia index (RHI) as a surrogate marker of endothelial function was measured using a fingertip peripheral arterial tonometry device in 247 T2DM patients with or without SCH. The 75-g oral glucose tolerance test was conducted, and the brachial-ankle pulse wave velocity was measured. Results: Compared with patients with euthyroidism (n=135), patients with SCH (n=112) had a lower RHI (1.60 ± 0.37 vs. 1.75 ± 0.41, P = 0.003), low-density lipoprotein cholesterol level (2.74 ± 0.91 vs. 2.99 ± 0.96 mmol/L, P = 0.037), estimated glomerular filtration rate (93.89 ± 23.23 vs. 100.3 ± 15.41 mL/min/1.73 m2, P = 0.016), and 30-min insulinogenic index (median, 17.76 [interquartile range: 8.72–27.75] vs. 39.40 [22.00–97.89], P < 0.001), and higher body mass index (26.13 ± 4.06 vs. 24.83 ± 3.17 kg/m2, P = 0.006) and area under the insulin curve (764.95 [493.04–1088.49] vs. 563.23 [345.71–887.20] pmol×h/L, P < 0.001). Patients with SCH was at increased risk of endothelial dysfunction (odds ratio = 2.845, 95% confidence interval: 1.090–7.427; P = 0.033), and the interaction between (BMI) and RHI (Pint = 0.02) was stronger in these patients than in patients with euthyroidism. Conclusion: SCH is likely associated with the deterioration of endothelial function in patients with T2DM, and thus, examination of thyroid function is recommended for patients with T2DM. Further research is needed to clarify the mechanism underlying this association.