Introduction: It has been hypothesized that autoimmunity may contribute to cardiovascular complications and may be an important trigger for processes leading to atherosclerosis, especially in type 1 diabetes mellitus (T1DM). This pilot study aimed to answer the question of whether markers of thyroid autoimmunity are associated with increased carotid intima-media thickness (cIMT) in young, asymptomatic T1DM women.
Material and methods: The study population consisted of 102 women, including 72 with T1DM and 30 healthy controls. All patients had thyroid hormones within the normal range. According to the antiperoxidase antibodies (aTPO) titre, the T1DM women were divided into an aTPO-positive (T1DM aTPO+) (n = 41) and an aTPO-negative (T1DM aTPO-) (n = 31) group. In all patients, aTPO, thyroglobulin antibody (aTG) titres, thyroid-stimulating hormone (TSH), free thyroxine (FT3), free triiodothyronine (FT4), lipid parameters, glycated haemoglobin, thyroid ultrasonography, and cIMT assessment were evaluated. The association of cIMT with different risk factors related to thyroid autoimmunity was determined.
Results: Carotid intima-media thickness was significantly greater in T1DM aTPO+ females (0.66 ± 0.10 mm) than in T1DM aTPO- (0.59 ± 0.11 mm) and healthy controls (0.58 ± 0.10 mm) (p = 0.007, p = 0.001, respectively). In all women cIMT was significantly, positively correlated with aTPO (p = 0.005, r = 0.273), Hashimoto's thyroiditis (HT) duration (p = 0.00015, r = 0.367), levothyroxine dose per week (p = 0.006, r = 0.269), and ultrasound features of HT (p = 0.004, r = 0.281) and inversely with fT3 concentration (p = 0.014, r = -0.243) and FT3/FT4 ratio (p = 0.042, r = -0.201). A logistic regression analysis showed that HT duration (OR: 1.102, 95% CI: 1.008-1.206, p = 0.032) and a positive history family of HT (OR: 3.909, 95%CI: 1.014-15.071, p = 0.045) were risk factors for increased cIMT. However, multivariate regression analysis showed that the studied parameters related to thyroid autoimmunity are not independent risk factors for increased cIMT.
Conclusions: We expanded the data on cIMT in young women with T1DM and showed that thyroid autoimmunity, and in particular the duration of exposure to anti-thyroid antibodies, despite adequate levothyroxine substitution, is associated with subclinical atherosclerosis in young women with T1DM. However, thyroid-related parameters are not independent risk factors for increased cIMT in euthyroid women.
Keywords: anti-thyroid antibodies; atherosclerosis; thyroid autoimmunity; type 1 diabetes.