Endocrine Abstracts

Introduction: Thyroid hormones modulate the insulin sensitivity and glucose metabolism. The interrelation between thyroid autoimmunity, thyroid function, glucose metabolism and cardiovascular risk factors remains uncertain.

Methods: We recorded thyroid function tests, BMI, IR markers comprising the Homeostasis Model Assessment for insulin resistance (HOMA-IR and HOMA-B), the Quantitative Insulin Sensitivity Check Index (QUICKI), HISI (Hepatic Insulin Sensitivity Index), WBISI (Whole-Body Insulin Sensitivity Index), IGI (Insulinogenic Index) and the levels of total cholesterol (TC), HDL, LDL-cholesterol, triglycerides (TG), apolipoprotein B (ApoB), ApoA1, lipoprotein (a) (Lp[a]), homocysteine, CRP (C-reactive protein), folic acid and vitamin B12 levels, in 354 patients with AIT, 93.5% woman, with a mean age of 46.0±15.5 years. A 75-g OGTT was performed and measurements of plasma glucose, insulin, and C-peptide were obtained. Statistical analysis was performed with the Mann-Whitney test and the Spearman’s correlations test. A two-tailed P≤0.05 was considered significant.

Results: After dividing the OGTT sample in 3 groups (IFG-16.6%, IGT- 24.2% and diabetes DM-9.6%), we found that patients with IFG had significantly higher levels than IGT patients in homocysteine (9.50±2.09 vs 7.24±1.33 μmol/l; P=0.002) and HOMA-IR (3.86±2.76 vs 2.14±1.00; P=0.01). The levels of CRP were significantly higher among patients with prediabetes comparing with normoglycemic patients (0.552±1.053 vs 0.346±0.467 mg/dl, P=0.003). In patients with prediabetes, we found lower levels of HISI (120.63±289.16 vs 59.00±65.91, P<0.001) and WBISI (7.30±5.66 vs 4.06±2.67, P<0.001), and higher levels of IGI (0.57±0.38 vs 1.16±0.77, P<0.001). Patients with prediabetes presented higher levels of TC (211±49 mg/dl vs 196±35 mg/dl, P=0.016) and LDL (133±37 mg/dl vs 120±28 mg/dl, P=0.002). In the whole sample we observed significant correlations between TSH and insulin (r=0.20; P=0.02), total cholesterol (r=0.10, P=0.04) and apoB (r=0.18, P=0.02). In the IFG group we found significant correlations between FT3 and TC (r=−0.53; P=0.01), LDL (r=- 0.57; P=0.006) and ApoB (r=−0.53; P=0.03). In IGT group we detected correlations between insulin and CRP (r=0.61; P=0.002), and between homocysteine and anti-TPO antibodies (r=0.46; P=0.02).

Conclusions: In patients with AIT, the presence of prediabetes is associated with higher cardiovascular risk. The screening of prediabetes with OGTT may be important in this group of patients to stratify the cardiovascular risk.