Influence of high-normal serum TSH levels on major cardiovascular risk factors and Visceral Adiposity Index in euthyroid type 2 diabetic subjects

Abstract

Although several observations indicate that serum TSH levels in the high normal range are related to cardiovascular (CVD) risk factors in the general population, similar data are limited in diabetic subjects. The aim of this study was to investigate the potential associations between TSH serum levels within the normal range and major metabolic and non-metabolic CVD risk factors in a cohort of euthyroid type 2 diabetic subjects. Thyroid hormones, TSH levels, anthropometric parameters, lipid profile, glucose control, and blood pressure were measured in 490 euthyroid type 2 diabetic subjects, consecutively attending two outpatient diabetic units in Southern Italy. In all subjects, we also calculated the Visceral Adiposity Index (VAI), an obesity-related index associated with CVD risk. Diabetic women showed higher mean serum TSH levels and lower FT4 concentration than diabetic men, while FT3 levels were comparable in the two genders. Stratifying the study population according to quartiles of TSH levels, subjects in the highest TSH quartile were more likely to be female and younger, with higher values of BMI and waist circumference (P = 0.05 both), higher triglycerides (P = 0.002) and non-HDL cholesterol concentrations (P = 0.01), higher VAI values (P = 0.02), and lower FT4 levels (P = 0.05), when compared to those in the lowest quartile. At multivariate analysis, a younger age, female gender, triglycerides levels, and waist circumference were independently associated with higher TSH levels. In conclusion, in type 2 diabetic subjects with no evidence of thyroid disease, higher TSH concentrations within the normal range were more frequent in women and in younger subjects, and they were associated with visceral obesity and higher triglycerides concentrations, two well-known CVD risk factors.

Beneficial effects of thyroid hormone on adipose inflammation and insulin sensitivity of obese Wistar rats

“…Taken together, our data suggest that the increased expression of TSHR and NIS in obese rats could maintain normal T4 production, even with reduced TSH serum levels. However, we cannot discard that the persistence of the obese state could lead to a future thyroid failure/impairment and a corresponding increase in TSH levels (Ruhla et al 2010;Giandalia et al 2014;Lee et al 2015). Lee et al (2015) reported increased TSHR, NIS, TPO, and TG mRNA content in high-fat diet-induced obese mice but, differently of our results, they showed increased TSH levels.…”

“…Although there are reports establishing a relationship between obesity and thyroid disorders, this issue still remains unclear. Reduced thyroid function has been observed in obese individuals (Ruhla et al 2010;Giandalia et al 2014). Moreover, increased serum thyrotropin (TSH), elevated triglycerides concentrations, and waist circumference were positively correlated in obese children (Shalitin et al 2009).…”

New association of bone morphogenetic protein 4 concentrations with fat distribution in obesity and Exenatide intervention on it

“…The results showed that BMP-4 levels were significantly higher in obesity with slight increased TSH than without increased TSH. Central obesity is associated with SH, especially the visceral fat deposition is related to increased TSH [37, 38]. Therefore, it may be the increased TSH with more serious visceral fat deposition that caused the higher BMP-4 levels in this study.…”

Key pathway and gene alterations in the gastric mucosa associated with obesity and obesity‐related diabetes

“…It places a spotlight on the gut-brain axis as a control system regulating energy metabolism. 13 Recently, Lee et al 14 identified an association between F I G U R E 2 RT-PCR validation of genes co-regulated in the simple obese (OB) and obese plus type 2 diabetes (OD) groups compared with the control (CON) group. In this study, we analyzed human gastric mucosa tissue samples to identify diseaserelated genes and pathways using a gene microarray and RT-PCR.…”