Aims: To examine whether Graves disease (GD) and Hashimoto thyroiditis (HT) are associated with insulin resistance (IR) and other cardiovascular risk factors. Patients and methods: We analyzed 479 patients with autoimmune thyroid disease, 354 (74%) with HT and 126 (26%) with GD, 94% woman, with a mean age of 46±16 years. The patients in both groups were properly treated in order to normalize TSH, FT3 and FT4 levels. We recorded thyroid function tests, BMI, IR markers comprising the homeostasis model assessment for insulin resistance, the quantitative insulin sensitivity check index, the hepatic insulin sensitivity index, the whole-body insulin sensitivity index, and the insulinogenic index. A 75-g OGTT was performed and measurements of plasma glucose, insulin, and C-peptide were obtained at 0 min (′), 30′, 60′, 90′ and 120′. We also recorded the levels of total cholesterol (TC), HDL, LDL-cholesterol, triglycerides (TG), apolipoprotein B (ApoB), ApoA1, lipoprotein (a), homocysteine, C-reactive protein, folic acid and vitamin B12 levels. Statistical analysis was performed with the MannWhitney U test and Spearmans correlations tests. Results are expressed as mean±S.D. A two-tailed P≤0.05 was considered significant.
Results: We found that patients with HT had significantly higher levels of BMI (26.5±5.3 vs 24.8±4.7 kg/m2, P=0.03); C-peptide at 30 min (7.3±2.8 vs 6.6±2.5 ng/ml; P=0.03); C-peptide at 60 min (10.5±4.2 vs 9.3±3.3 ng/ml; P<0.01). In patients with HT we also found significantly higher levels of LDL-cholesterol (124±31 vs 116±33 mg/dl; P<0.01), TG (116±70 vs 104±75 mg/dl; P=0.034), ApoB (97±23 vs 86±24 mg/dl; P<0.001), B12 vitamin (467±308 vs 372±174 pg/ml; P=0.02), anti-thyroglobulin antibody (141.7±179.0 vs 121.2±160.3 UI/ml, P=0.01). We found a negative correlation between TSH and TRAb levels (r=−0.180; P<0.001). In the whole group TSH positively correlated with TC (r=0.097; P=0.04) and ApoB (r=0.117; P=0.02). Conclusions: After treatment to normalize thyroid function, HT patients have a higher cardiovascular risk than GD patients, associated with overweight, subclinical inflammation and atherogenic lipid profile.
Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.
Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.