Thyroid hormones are positively associated with insulin resistance early in the development of type 2 diabetes

Thyroid Hormones and Diabetes in Euthyroid Hispanic/Latino Adults of Diverse Backgrounds: HCHS/SOL

Context

Previous studies have demonstrated associations of endogenous thyroid hormones with diabetes; less is known about stages of diabetes development at which they are operative, mechanisms of associations, and the role of the hypothalamic-pituitary-thyroid axis.

Objective

This study examined associations of thyroid hormones with incident prediabetes and diabetes and with changes in glycemic traits in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL), the largest cohort of Hispanic/Latino adults with diverse backgrounds in the United States.

Methods

The study includes 592 postmenopausal euthyroid women and 868 euthyroid men aged 45 to 74 years without diabetes at baseline participating in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL). Baseline hormones included thyrotropin (TSH), free thyroxine (FT4), total triiodothyronine (T3), and indices calculated from thyroid hormones evaluating pituitary sensitivity to thyroid hormone. Transitions to diabetes and prediabetes, and changes in glycemic traits determined at the 6-year follow-up visit, were examined using multivariable Poisson and linear regressions.

Results

Among women, T3 (incident rate ratio [IRR] = 1.65; 95% CI, 1.22-2.24; P = .001) and TSH (IRR = 2.09; 95% CI, 1.01-4.33; P = .047) were positively, while FT4 (IRR = 0.59; 95% CI, 0.39-0.88; P = .011) was inversely, associated with transition from prediabetes to diabetes. Among men, the T3/FT4 ratio was positively associated with transition from normoglycemia to prediabetes but not from prediabetes to diabetes. Indices measuring sensitivity of the pituitary to thyroid hormone suggested increased sensitivity in men who transitioned from prediabetes to diabetes.

Conclusion

Positive associations in women of T3 and TSH and inverse associations of FT4, as well as inverse associations of thyroid indices in men with transition from prediabetes to diabetes, but not from normoglycemia to diabetes, suggest decreased pituitary sensitivity to thyroid hormones in women and increased sensitivity in men later in the development of diabetes.

Lipoprotein Ratios: Correlation With Glycated Hemoglobin (HbA1c) Among Thyroid Disorders' Patients

INTRODUCTION

Thyroid disorders and diabetes mellitus are prevalent conditions in the modern era. Moreover, glycated hemoglobin (HbA1c) is the established (prognostic as well as diagnostic) marker for long-term glycemic control, whereas the lipid profile is the marker for cardiovascular risks. The association of hypothyroidism with dyslipidemia is also a well-established fact. The current study explores a correlation between thyroid profile, glycemic status, and various lipoprotein indices.

OBJECTIVE

To look for an association between thyroid profile, glycemic status, and various lipoprotein indices.

METHODOLOGY

The cross-sectional study conducted at AIIMS Gorakhpur included a total of 108 subjects, with 37 normal subjects (Group I) and 71 patients) with T2DM (Type-2 diabetes mellitus) (Group II). Baseline characteristics of the two groups were compared for age, sex, presence of hypertension, fasting blood glucose, and body mass index (BMI). Blood samples were collected from the patients. The sera were analyzed for HbA1c and lipid profile, which included total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C). Serum samples were also used to estimate the thyroid stimulating hormone (TSH) and triiodothyronine (fT3). The association between thyroid profile, glycemic status, and various lipoprotein indices was calculated.

STATISTICAL ANALYSIS

 Kolmogorov-Smirnov test for normality of the data. Spearmann correlation was used for nonparametric data.

RESULTS

There were significantly higher levels of total cholesterol, triglycerides, and LDL-C levels in T2DM subjects than in non-diabetic subjects. There was also a significant positive correlation observed between TSH and TC among the normal control group (ρ =0.348, P=0.04). Similarly, significant positive correlations were found for TG (ρ =0.354, P=0.04) and LDL-C (ρ =0.431, P=0.03) among non-diabetic subjects. Among patients with T2DM, TSH was significantly correlated positively with TG (ρ =0.530, P=0.006) and LDL-C (ρ =0.443, P=0.03). Similarly, in the same group, among lipid ratios, TG/HDL-C (ρ =0.311, P=0.04) and LDL-C/HDL-C (ρ =0.227, P=0.05) were significantly correlated to TSH. Furthermore, there were significant positive correlations between TSH and HbA1c (ρ =0.301, P=0.04). fT3 was found to have a strong negative correlation with HbA1c among patients with T2DM (ρ =-0.454, P=0.02).

CONCLUSION

Thyroid disorders exert significant effects on glycemic control and lipid metabolism, which may impact HbA1c levels and lipid profile parameters.

Humero-femoral index and diabetes risk in the US population- a case study

Background

The between-subject variability in diabetes risk persists in epidemiological studies, even after accounting for obesity. We investigated whether the humero-femoral index (HFI) was associated with prevalence of type 2 diabetes mellitus (T2DM) and assessed the incremental value of HFI as a marker of T2DM.

Methods

This population-based cross-sectional study used data from the National Health and Nutrition Examination Survey from 1999 to 2018. We assessed 42,088 adults aged ≥ 30 years. HFI was defined as the upper arm length/upper leg length ratio. The outcome included undiagnosed diabetes (based on 2-hour plasma glucose levels, fasting glucose and hemoglobin A1C) and history of diabetes (diagnosed diabetes or taking antidiabetic drugs).

Results

As compared with the bottom quartile, the prevalence ratio of T2DM was 1.28 (95% CI 1.19-1.38) in the second, 1.61 (95% CI 1.50-1.72) in the third, and 1.75 (95% CI 1.64-1.88) in the fourth quartile of HFI (P for trend < 0.0001). The positive association remained consistent within different patterns of BMI and WC in men but was rendered null in women. After adding HFI to the reference model (including WC only), the discrimination slopes increased by 60.0% in men and 51.1% in women.

Conclusion

Our findings suggest that HFI may be a key component in body structure contributing to the risk of T2DM. In men, the highest HFI was associated with elevated prevalence of T2DM, independent of BMI and WC.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01251-z.

Thyroid function, sensitivity to thyroid hormones, and metabolic syndrome in euthyroid children and adolescents with Down syndrome

PURPOSE

Patients with Down Syndrome (DS) showed multiple comorbidities, including thyroid disorders, obesity, and metabolic derangement. Different thyroid hormone (THs) patterns and sensitivity to thyroid hormone indices (STHI) seem to be associated with metabolic disorders. The study's aim was to evaluate the prevalence of metabolic syndrome (MS) in pediatric patients affected by DS, taking into consideration the relationship between the metabolic parameters, THs and STHI.

METHODS

We enlisted 50 euthyroid patients with DS (9.03 ± 4.46). Clinical parameters, TSH, FT3, FT4 and the presence of MS were recorded. Indexes of peripheral sensitivity (FT3/FT4 ratio) and central sensitivity (TSH index, TSHI; TSH T4 resistance index, TT4RI; TSH T3 resistance index, TT3RI) were also detected. Thirty healthy subjects were included as a control group.

RESULTS

MS was detected in 12% of the subjects with DS. FT3, FT4, and TSH levels were higher in DS than in the control group (p < 0.01); higher levels of FT3/FT4 ratio, TSHI and TT3RI and lower TT4RI values (p < 0.01) were also detected. A significant correlation was detected between FT3 and fasting blood glucose (FBG) (R = 0.46), triglyceride (TG) (r = 0.37), total (r = 0.55) and high density lipoprotein-cholesterol (HDL-C) (r = - 0.38), diastolic blood pressure (DBP) (r = - 0.4); FT3/FT4 ratio and waist circumference (WC) (r = 0.36); TSHI and total (r = 0.30) and HDL cholesterol (r = - 0.31); TT4RI and HDL cholesterol (r = - 0.31); TT3RI and total (r = 0.39) and HDL cholesterol (r = - 032).

CONCLUSION

We confirmed a higher MS prevalence in children with DS compared to the control group. A significant association between THs, STHI, and the glucose and lipid metabolism parameters was detected supporting their role in metabolic alterations related to the DS.

Thyroid hormone sensitivity and diabetes onset: a longitudinal cross-lagged cohort

Purpose

Thyroid hormones sensitivity is a newly proposed clinical entity closely related with metabolic health. Prior studies have reported the cross-sectional relationship between thyroid hormones sensitivity and diabetes; however, the longitudinal association is unclear to date. We aimed to explore the relationship between impaired thyroid hormone sensitivity at baseline and diabetes onset using a cohort design.

Methods

This study enrolled 7283 euthyroid participants at the first visit between 2008 and 2009, and then annually followed until diabetes onset or 2019. Thyrotropin (TSH), free triiodothyronine (FT3) and free thyroxine (FT4) were measured to calculate thyroid hormone sensitivity by thyroid feedback quantile-based index (TFQI), Chinese-referenced parametric thyroid feedback quantile-based index (PTFQI), thyrotropin index (TSHI), thyrotroph thyroxine resistance index (TT4RI) and FT3/FT4 ratio. Cox proportional hazard model and cross-lagged panel analysis were used.

Results

The mean baseline age was 44.2 ± 11.9 years, including 4170 (57.3%) male. During a median follow-up of 5.2 years, 359 cases developed diabetes. There was no significant association between thyroid hormones sensitivity indices and diabetes onset, and adjusted hazard ratios per unit (95% CIs) were 0.89 (0.65-1.23) for TFQI, 0.91 (0.57-1.45) for PTFQI, 0.95 (0.70-1.29) for TSHI, 0.98 (0.70-1.01) for TT4RI and 2.12 (0.17-5.78) for FT3/FT4 ratio. Cross-lagged analysis supported the temporal association from fasting glucose to impaired thyroid hormones sensitivity indices.

Conclusions

Our findings could not demonstrate that thyroid hormones sensitivity status is a predictor of diabetes onset in the euthyroid population. Elevated fasting glucose (above 7.0 mmol/L) appeared to precede impaired sensitivity indices of thyroid hormones.

Thyroid dysfunction in children and adolescents affected by undernourished and overnourished eating disorders

Eating disorders (ED) are one of the most prevalent chronic disorders in adolescents and young adults, with a significantly increasing prevalence in younger children, particularly in girls. Even if obesity in essence is not framed as an eating disorder and has always been considered a separate pathology, ED and obesity could be considered part of a continuum. It has become evident that one condition can lead to another, such as binge eating disorder (BED) and bulimia nervosa, and that they share the same repercussions in terms of psychosocial, metabolic, and nutritional health. This narrative review aims to investigate the hypothalamic-pituitary-thyroid axis in undernourished and overnourished patients with ED, including obesity, in order to highlight the relationship between weight control and thyroid function and its effects and to consider therapeutic and preventive strategies in children and adolescents. Literature data report that thyroid alterations occur in patients with ED, both underweight and overweight, and represent a continuum of changes depending on the severity and time course of the disease involving the endocrine system. Considering the relevant role thyroid hormones (TH) play not only in energy expenditure (EE) but also in metabolic control and cardiovascular risks related to dysmetabolism and mood regulation, continuous monitoring of thyroid homeostasis in patients with ED is mandatory to prevent severe complications and to start early treatment when necessary.

The effect of Central and peripheral thyroid resistance indices on diabetic retinopathy: a study of hospitalized euthyroid patients with T2DM in China

OBJECTIVE

This study aims to explore the correlation between central and peripheral thyroid resistance indices and diabetic retinopathy(DR) in patients with type 2 diabetes mellitus (T2DM), so as to provide a clinical basis for the prevention and treatment of diabetic retinopathy.

METHODS

This study retrospectively analyzed 1249 euthyroid patients with T2DM hospitalized in the Department of Endocrinology, Peking University International Hospital from January 2017 to June 2022, including 852 males and 397 females, with an average age of 54.73 ± 13.40 years. According to the degree of DR, the patients were divided into three groups including the no diabetic retinopathy (NDR) group, non-proliferative diabetic retinopathy (NPDR) group and proliferative diabetic retinopathy (PDR) group.

RESULTS

Free thymidine (FT4), thyroid stimulating hormone (TSH), thyroid feedback quantile index (TFQI), thyrotropin-T4 resistance index (TT4RI), thyroid stimulating hormone index (TSHI) and free triiodothyronine/free thyroxine (FT3/FT4) levels among the three groups were significantly different, with the NDR group having lowest TSH, TFQI, TT4QI, TSHI and the highest in the PDR group (all p < 0.05). Logistic regression showed that after adjusting for age, body mass index (BMI), sex, diabetes duration, blood pressure, blood lipid, HbA1c, lower level of FT4 was an independent risk factor for DR, high level of TSH, TFQI, TSHI and TT4RI were independent risk factors for DR. Central and peripheral thyroid sensitivity indices have predictive value for DR, the overall predictive accuracy of FT3/FT4 was 0.61 (95%CI 0.57, 0.65), the overall predictive accuracy of TFQI was 0.66(95%CI 0.63, 0.70), the overall predictive accuracy of TSHI was 0.66(95%CI 0.62, 0.68), the overall predictive accuracy of TT4RI was 0.63 (95%CI 0.59, 0.66).

CONCLUSION

The reduction of central and peripheral thyroid hormone sensitivity is an independent risk factor for DR. These results can help predict the risk of the occurrence and development of DR, which may provide a clinical basis for the prevention and treatment of DR in T2DM patients.

Reference intervals for thyroid biomarkers to enhance the assessment of thyroid status in childhood and adolescence

OBJECTIVES

The determination of assay-dependent upper and lower reference limits (URL, LRL) of free triiodothyronine (FT3), free thyroxine (FT4), and thyroid stimulating hormone (TSH) during childhood and adolescence, is challenging.

METHODS

Thyroid hormones were measured via the Abbott Alinity system in 502 euthyroid children partitioned in the following age groups: ≤2, 2.1-10, and 10.1-18 years. The 97.5th and 2.5th percentiles (URL and LRL) were derived according to CLSI EP28- A3c guidelines. Quantile regression models were used to assess: (a) 90% confidence intervals of the URL and LRL, (b) the effect of age on URL and LRL within each age class and on overall age range, (c) the difference between the URLs and LRLs estimated for each age partition with an estimate of the confidence interval divided by the reference interval being derived (CI/RI).

RESULTS

The CI/RI for the LRLs are smaller as compared to the URLs, except for FT4 for the 2.1-10 years age group. Considering the CI/RI and the overlap between CIs across the three age groups, one single LRL might be considered for TSH, FT3 and FT4 between 0 and 18 years. However, for the URL, there was a noticeable decrease in the URL over the 3 age groups for all three biomarkers, with there being no overlap in CIs for the URL between the ≤2 vs. the 10.1-19 years age groups.

CONCLUSIONS

A common LRL for TSH, FT4 and FT3 for patients aged ≤18 years may be utilized when these biomarkers are measured with the Alinity system. For the URLs the use of age-specific URLs for these biomarkers is recommended.

Thyroid Function and Metabolic Syndrome in Children and Adolescents with Neuromotor Disability

Thyroid function plays a crucial role in nervous system integrity and metabolic homeostasis. We evaluated the pattern of TSH, FT4 and FT3 release in children with neuromotor impairment (NI) in relationship with metabolic syndrome (MS). We enrolled 55 patients with NI and 30 controls. Clinical parameters, thyroid function and MS presence were recorded. Principal component analysis (PCA), cluster analysis, and logistic regression models were performed. MS was detected in 54.5% of patients. Four clusters were identified: the first one included only controls and, contrasting with cluster 4, was exclusively characterized by children with disability and MS. This latter showed increased FT4 and FT3 and decreased TSH levels. Cluster 2, characterized by disability without MS showed high FT4 and FT3, whereas cluster 3 with low FT4 and FT3 mainly included disability (90%) and showed prevalent MS (57%). The association between TSH and NI is represented by a U-shape structure. The TSH, FT3 and FT4 release patterns may reflect thyrotropic adaptation, allostatic response and compensatory mechanisms. These mechanisms, found in both MS and disability, show that the odds of having a condition of NI with or without MS increase as the TSH values deviate, in both directions, from a value of 2.5 mLU/mL.

Oxidative Stress and DNA Damage in Peripheral Blood Mononuclear Cells from Normal, Obese, Prediabetic and Diabetic Persons Exposed to Thyroid Hormone In Vitro

Diabetes, a chronic group of medical disorders characterized byhyperglycemia, has become a global pandemic. Some hormones may influence the course and outcome of diabetes, especially if they potentiate the formation of reactive oxygen species (ROS). There is a close relationship between thyroid disorders and diabetes. The main objective of this investigation was to find out whether peripheral blood mononuclear cells (PBMCs) are more prone to DNA damage by triiodothyronine (T₃) (0.1, 1 and 10 μM) at various stages of progression through diabetes (obese, prediabetics, and type 2 diabetes mellitus—T2DM persons). In addition, some biochemical parameters of oxidative stress (catalase-CAT, thiobarbituric acid reactive substances—TBARS) and lactate dehydrogenase (LDH) were evaluated. PBMCs from prediabetic and diabetic patients exhibited increased sensitivity for T₃ regarding elevated level of DNA damage, inhibition of catalase, and increase of TBARS and LDH. PBMCs from obese patients reacted in the same manner, except for DNA damage. The results of this study should contribute to a better understanding of the role of thyroid hormones in the progression of T2DM.

Thyroid Function and the Risk of Prediabetes and Type 2 Diabetes

CONTEXT

Thyroid hormones are important regulators of glucose metabolism, and studies investigating the association between thyroid function and type 2 diabetes incidence have shown conflicting results.

OBJECTIVE

We aimed to combine the evidence from prospective studies addressing the association between thyroid function and type 2 diabetes risk.

METHODS

We systematically searched in Embase, Medline (Ovid), Web of Science, Cochrane, and Google Scholar for prospective studies assessing the association of thyroid function and incident type 2 diabetes. Data extraction was performed using a standardized protocol by 2 independent reviewers. We assessed study quality using the Newcastle-Ottawa Scale and pooled hazard ratios (HRs) and 95% CI using random-effects models.

RESULTS

From the 4574 publications identified, 7 met our inclusion criteria and were included in the qualitative synthesis. Six publications were included in the meta-analysis. Studies assessed hypothyroidism (6 studies), hyperthyroidism (5 studies), thyrotropin (TSH) in the reference range (4 studies), and free thyroxine (FT4) in the reference range (3 studies) in relation to incident type 2 diabetes. The pooled HR for the risk of type 2 diabetes was 1.26 (95% CI, 1.05-1.52) for hypothyroidism, 1.16 (95% CI, 0.90-1.49) for hyperthyroidism, 1.06 (95% CI, 0.96-1.17) for TSH in the reference range, and 0.95 (95% CI, 0.91-0.98) for FT4 in the reference range.

CONCLUSION

Current evidence suggests an increased type 2 diabetes risk in people with hypothyroidism and lower FT4 levels in the reference range. Further population-based studies are needed to address this association given the limited evidence.

Relationship between subclinical hypothyroidism and distal-symmetric diabetic polyneuropathy in type 2 diabetes mellitus referred to Kosar Hospital in Semnan and related indicators in 2019–2020

Introduction:

Diabetes is one of the most common metabolic diseases and one of its important complications is diabetic neuropathy. Due to the relationship between diabetes and thyroid disorders, the present study was performed to determine the association between subclinical hypothyroidism and end-stage diabetic polyneuropathy in patients with type 2 diabetes.

Materials and Methods:

In this descriptive, analytical study, 154 patients with type 2 diabetes referred to Kosar Hospital in Semnan were evaluated. After recording their demographic information, samples were received for biochemical testing. The patients’ neuropathy was then evaluated based on the United Kingdom screening test (UKST). The results were recorded in the data collection form and then analyzed using SPSS Statistics 22 software.

Results:

In this study, 154 patients were studied, including 49 with subclinical hypothyroidism and 105 with euthyroid. The results of the present study showed that the mean age of patients in the subclinical hypothyroid group was 60.08 years and in the euthyroid group was 60.77 years. Mean ± standard deviation (SD) of the patients’ age, blood pressure, duration of diabetes, body mass index, fasting blood sugar (FBS) and Glucose, and 2-hour post prandial (2HPP) were not statistically significant between the two groups. The frequency of neuropathy severity based on clinical signs during examination and symptoms mentioned by the patients in the two groups was statistically significant (P = 0.005 and P = 0.001, respectively). The severity of neuropathy was not significantly associated with thyroid-stimulating hormone (TSH) levels (P > 0.05).

Conclusion:

From the results of the present study, it can be concluded that the severity of neuropathy based on the clinical signs during examination and the symptoms mentioned by the patient in diabetic patients is related to subclinical hypothyroidism. Further studies are recommended.

sCD40L Is Increased and Associated with the Risk of Gestational Diabetes Mellitus in Pregnant Women with Isolated TPOAb Positivity

BACKGROUND

Autoimmune disorders are associated with gestational diabetes mellitus (GDM) in pregnant women who were positive for thyroid peroxidase antibody (TPOAb). Soluble CD40 ligand (sCD40L) and soluble interleukin-2 receptor (sCD25) are abnormally expressed in autoimmune diseases and are reliable markers of inflammation. The purpose of this study was to evaluate sCD40L and sCD25 in early pregnancy and investigate their correlation with GDM and TPOAb.

METHODS

A total of 126 pregnant women in the first trimester were enrolled for analysis: 93 were positive for TPOAb and 33 were negative for TPOAb. Demographical and clinical data in early pregnancy were collected. A total of 123 participants underwent a 75 g oral glucose tolerance test in the second trimester. Serum sCD40L and sCD25 levels were measured by ELISA.

RESULTS

The incidence of GDM was 24.4% in pregnant women with isolated TPOAb positivity in our study. Both sCD40L and sCD25 were positively correlated with TPOAb (r = 0.476, P < 0.001; r = 0.188, P < 0.05). sCD40L was highest in (P < 0.001) Ab-positive women with GDM group (P < 0.05). After adjusting for TPOAb, age, TSH, FT4, triglycerides, and low-density lipoprotein cholesterol, multivariate logistic regression analysis showed that sCD40L was an independent risk factor for GDM in pregnant women with TPOAb positivity (odds ratio = 3.235, 95% confidence interval 1.024-10.218, P < 0.05).

CONCLUSIONS

About a quarter of pregnant women with isolated positive TPOAb might have GDM. sCD40L was an independent risk factor for GDM in women with isolated TPOAb positivity.

The Relationship Between Type 2 Diabetes Mellitus and Related Thyroid Diseases

Diabetes and thyroid diseases are caused by endocrine dysfunction and both have been demonstrated to mutually impact each other. Variation in thyroid hormone levels, even within the normal range, can trigger the onset of type 2 diabetes mellitus (T2DM), particularly in people with prediabetes. However, the available evidence is contradictory.

The purpose of this review is to understand the pathological relationship between thyroid-related disorders and T2DM.

T2DM in thyroid dysfunction is thought to be caused by altered gene expression of a group of genes, as well as physiological abnormalities that result in decreased glucose uptake increased, splanchnic glucose absorption, disposal in muscles, increased hepatic glucose output. Additionally, both hyperthyroidism and hypothyroidism can cause insulin resistance. Insulin resistance can develop in subclinical hypothyroidism as a result of a reduced rate of insulin-stimulated glucose transfer caused by a translocation of the glucose transporter type 2 (GLUT 2) gene. On the other hand, novel missense variations in (Thr92Ala) can cause insulin resistance. Furthermore insulin resistance and hyperinsulinemia resulting from diabetes can cause culminate in goitrous transformation of the thyroid gland.

Thyroid-related diseases and T2DM are closely linked. Type 2 diabetes can be exacerbated by thyroid disorders, and diabetes can worsen thyroid dysfunction. Insulin resistance has been found to play a crucial role in both T2DM and thyroid dysfunction. Therefore, failure to recognize inadequate thyroid hormone levels in diabetes and insulin resistance in both conditions can lead to poor management of patients.

Independent associations of thyroid-related hormones with hepatic steatosis and insulin resistance in euthyroid overweight/obese Chinese adults

PURPOSE

The aim of the study is to explore the independent association of free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH) with hepatic steatosis and insulin resistance.

METHODS

A cross-sectional study of 88 overweight/obese adults who underwent anthropometric measurements [BMI, waist circumference (WC) and waist-to-height ratio (WHtR)], hepatic steatosis assessment (FibroScan) and thyroid-related hormones tests was conducted from 2018 to 2020 in Xiamen, China.

RESULTS

Subjects with increasing tertiles of FT3 showed significantly higher levels of controlled attenuation parameter (CAP) ((295.4 ± 44.1, 290.1 ± 68.2 and 331.7 ± 43.6 (dB/m) for tertile 1-3, respectively, p = 0.007) and fatty liver index (FLI) score (47.7 (33.9-60.8), 61.5 (45.1-88.9) and 90.5 (84.5-94.8), respectively, p < 0.001). FT3 significantly and positively correlated with obesity index (BMI, WC, and WHtR), homeostatic model assessment of insulin resistance (HOMA-IR) and hepatic steatosis (CAP and FLI). Multivariable linear regression analyses with adjustment for potential confounding factors showed FT3 was independently associated with BMI (regression coefficient (β (95%CI): 0.024 (0.004-0.043), p = 0.020), HOMA-IR (β (95%CI): 0.091 (0.007-0.174), p = 0.034), CAP (β (95%CI): 25.45 (2.59-48.31), p = 0.030) and FLI (β (95%CI): 0.121 (0.049-0.194), p = 0.001). Neither FT4 nor TSH was significantly associated with any indicators of obesity, insulin resistance or hepatic steatosis.

CONCLUSIONS

Increased FT3, but not FT4 or TSH, was independently associated with higher risks of hepatic steatosis and insulin resistance in euthyroid overweight/obese Chinese adults. Trial registration Registration is not applicable for our study.

Does serum TSH level act as a surrogate marker for psychological stress and cardio-metabolic risk among adolescent and young people?

OBJECTIVES

The incidence of metabolic syndrome is increasing even at younger ages. Metabolic syndrome constitutes a group of cardiovascular risk factors that include high cholesterol, triacylglycerol, hyperglycemia, central obesity, etc., which increases the risk of cardiovascular disease, diabetes mellitus, may be even cancer. Indian students enter colleges just after crossing their adolescent age and will be exposed to greater academic stress. Psychological stress or depression is associated with transient change in thyroid hormones level or dysfunction. To explore an association among serum Thyroid Stimulating Hormone (TSH) levels, fT3:fT4 ratio, psychological stress scores, and selected known cardio-metabolic risk markers.

METHODS

Forty first year MBBS students were included. Their demographic, anthropometric variables, and the blood pressure were documented. Serum TSH, fT3, fT4, and salivary cortisol level was quantified. The stress level was assessed using Cohen Perceived Stress Scale Scoring. Data were expressed in mean ± standard deviation. Data (parametric/non-parametric) were compared by Independent unpaired ANOVA or Kruskal Wallis test whichever is appropriate. Spearmen correlation analysis was performed.

RESULTS

Serum TSH and Cohen stress score are negatively correlated (r=-0.152), but serum cortisol showed (r=0.763) a positive correlation. TSH levels and the marks obtained in the summative assessments were negatively correlated and the correlation was not statistically significant.

CONCLUSIONS

The psychological stress is associated with low serum TSH, high cortisol, and poor academic performance in first year MBBS students. Blood pressure, plasma glucose, and anthropometric measures were not associated with the psychological stress.

The role of incretins and incretin-based drugs in autoimmune diseases

Incretin hormones, including glucagon-like peptide (GLP)-1, GLP-2 and glucose-dependent insulinotropic polypeptide (GIP), are gastrointestinal peptides secreted from enteroendocrine cells. These hormones play significant roles in many physiological processes via binding to G-protein coupled receptors (GPCRs) on different organs and tissues; one of them is the immunomodulatory effect on the immune system and its molecular components such as cytokines and chemokines. Anti-inflammatory effects of incretins and dependent molecules involving long-acting analogs and DPP4 inhibitors through regulation of T and B cell activation may attenuate autoimmune diseases caused by immune system disorders in mistakenly recognizing self as the foreign agent. In this review, we investigate incretin effects on the immune system response and the potential benefits of incretin-based therapy for treating autoimmune diseases.

Daily intake of yogurt drink fortified either with vitamin D alone or in combination with added calcium causes a thyroid-independent increase of resting metabolic rate in adults with type 2 diabetes: a randomized double blind clinical trial

We investigated the effect of daily intake of yogurt drink fortified with either vitamin D alone or with added calcium on resting metabolic rate (RMR), thyroid hormones and homeostatic model assessment for insulin resistance (HOMA-IR) in subjects with type 2 diabetes (T2D). A total of 75 adult subjects with T2D were randomly assigned to one of the three groups to receive either D-fortified yogurt drink (DY; 1000 IU vitamin D/d), Ca-D-fortified yogurt drink (CDY; 1000 IU vitamin D plus 500 mg calcium), or plain yogurt drink (PY) for 12 weeks. All assessments were done at the baseline and after the intervention. The concentrations of anti-thyroid peroxidase antibody (anti-TPO-Ab), intact parathyroid hormone (iPTH) and thyroid stimulating hormone (TSH) had significant decline compared with baseline values only in CDY group. The mean RMR increased in both DY and CDY groups (p<0.001 for both). Also, changes of serum concentrations of 25(OH)D (B= 2.96, 95%CI= 1.3- 4.6, p=0.001) and iPTH (B= -2.41, 95%CI= -4.5- -0.31, p=0.025) remained significant predictors of RMR changes even after adjustment for changes of serum concentrations of TSH (B= -18.2, 95%CI= -61.7- 25.2, p=0.406). Daily intake of vitamin D together with calcium at physiological doses has attenuating effect on anti-TPO-Ab and TSH. Also, vitamin D with or without added calcium causes a significant thyroid-independent increase in RMR in euthyroid subjects with T2D. Registered at clinicaltrials.gov as NCT01229891. Novelty: Daily intake of vitamin D with calcium at physiological doses has attenuating effect on anti-TPO-Ab and TSH. Vitamin D with or without added calcium causes a thyroid-independent increase in RMR in euthyroid subjects with T2D.

The relationships between thyroid-stimulating hormone level and insulin resistance, glucose effectiveness, first- and second-phase insulin secretion in Chinese populations

Increased insulin resistance (IR); decreased glucose effectiveness (GE); and both first-and second phase of insulin secretion (FPIS, SPIS) have always been important factors for the development of type 2 diabetes. Therefore, in this study, we evaluated the relationships between thyroid-stimulating hormone (TSH) and these 4 factors in adult Chinese. We randomly enrolled 24,407 men and 24,889 women between 30 and 59 years old. IR, FPIS, SPIS and GE were measured with the equations built by our group. IR = log (1.439 + 0.018 × sex - 0.003 × age + 0.029 × BMI - 0.001 × SBP + 0.006 × DBP + 0.049 × TG - 0.046 × HDLC - 0.0116 × FPG) × 10 ^3.333. FPIS = 10 [1.477 - 0.119 × FPG + 0.079 × BMI - 0.523 × HDLC]. SPIS = 10 [-2.4 - 0.088 × FPG + 0.072 × BMI]. GE = (29.196 - 0.103 × age - 2.722 × TG - 0.592 × FPG) ×10 ^−3. The t test was performed to evaluate the differences between normal and diabetic groups. To evaluate the differences of the mean values of the 4 groups, from the highest to the lowest levels of TSH, we used a one-way analysis of variance. Age, high density lipoprotein-cholesterol and GE were higher in women. On the other hand, body mass index, blood pressure, low density lipoprotein-cholesterol, triglyceride, FPIS, SPIS and IR were higher in men. TSH was positively related to IR, FPIS, and SPIS and negatively related to GE. According to the r values, the tightest relationship was between TSH and IR, followed by GE, FPIS and SPIS. In conclusion, our data showed that IR, FPIS, and SPIS were positively related to the TSH level in middle-aged Chinese, whereas GE was negatively related. In both genders, IR had the tightest association followed by GE, FPIS, and SPIS.

A longitudinal study of thyroid markers during pregnancy and the risk of gestational diabetes mellitus and post-partum glucose metabolism

AIMS

To determine the relationship between thyroid markers during pregnancy and gestational diabetes mellitus (GDM) or post-partum glucose metabolism.

MATERIALS AND METHODS

Based on pregnancy 75-g oral glucose tolerance test (OGTT) results, 1467 subjects were grouped into normal glucose tolerance (NGTp; n = 768) and GDM (n = 699) groups. Furthermore, based on post-partum 75-g OGTT results, 286 GDM subjects, screened for glucose metabolism after delivery, were grouped into NGTd (n = 241) and abnormal glucose tolerance (AGT; n = 45) groups.

RESULTS

Maternal age, family history of diabetes, acanthosis nigricans, previous adverse pregnancy outcomes and caesarean section incidence, and thyroid positive antibody rates were higher in the GDM group than in the NGTp group. In the first trimester, free triiodothyronine (FT3), thyroid peroxidase antibody (TPOAb) and thyroglobulin antibody (TgAb) levels were higher in the GDM group than in the NGTp group. In the second trimester, free thyroxine (FT4) levels were lower and TPOAb and TgAb levels were higher in the GDM group than in the NGTp group. After adjusting for confounding factors, FT3, TPOAb and TgAb (first trimester), and FT4, TPOAb and TgAb (second trimester) were risk factors for GDM. TPOAb and TgAb levels were higher in the AGT group than in the NGTd group and were potential predictors of abnormal post-partum glucose tolerance.

CONCLUSIONS

GDM risk significantly increased with increased FT3 (first trimester), TPOAb and TgAb (first and second trimesters) or with decreased FT4 (second trimester). Presence of thyroid antibodies predicted post-partum glucose abnormalities in subjects with GDM.

Lower free thyroid hormone levels are associated with high blood glucose and insulin resistance; these normalize with metabolic improvement of type 2 diabetes

OBJECTIVE

This study aimed to explore the relationship of thyroid function and glucose metabolism and to investigate the changes in thyroid function after National Metabolic Management Center (MMC) management in type 2 diabetic mellitus (T2DM).

METHODS

A total of 2000 euthyroid participants from MMC in Shanghai General Hospital and a community physical examination were recruited. They were categorized into four groups: normal glucose tolerance (NGT, n = 132), prediabetes (N = 147), DM well-controlled (T2DM with glycosylated hemoglobin [HbA1c] ≤ 7%, n = 505), and DM uncontrolled (T2DM with HbA1c > 7%, n = 1216). The parameters were compared among the groups and their changes before and after MMC follow-up in DM uncontrolled group were observed.

RESULTS

Free triiodothyronine (FT3) and free thyroxine (FT4) levels varied significantly among groups. FT3 and FT4 levels negatively correlated with HbA1c level (P < 0.05), and positively correlated with the estimated glucose disposal rate (eGDR) (P < 0.05). Following MMC management, blood glucose and insulin resistance in the DM uncontrolled group were dramatically improved (P < 0.001). Meanwhile, FT3 was elevated compared to the baseline (from 4.51 ± 0.78 pmol/L to 4.68 ± 0.87 pmol/L, P < 0.05), and reverse triiodothyronine (r-T3) decreased from 1.03 ± 0.24 nmol/L to 0.92 ± 0.25 nmol/L (P < 0.001). Thyroid-stimulating hormone significantly decreased as well (P < 0.001).

CONCLUSIONS

Decreased free thyroid hormone levels in normal range were associated with high glucose and insulin resistance. After MMC management, improvement of blood glucose and insulin resistance were accompanied by the restoration of low-normal thyroid function.

Thyroid Lesion as a Manifestation of Comorbidity in Patients with Diabetic Polyneyropathy

The study of clinical and anamnestic and paraclinical characteristics, highlighting their dominant features in patients with DP and existing thyroid diseases occupies an important place in modern neuroendocrinology and requires more focused attention of clinicians. The objective: to determine the leading clinical and laboratory-instrumental parameters in patients with DP and thyroid pathology, to analyze the mutual influence of neuroendocrine pathology on the patient’s somatoneurological condition. Materials and methods. Was done a clinical examination of 64 patients with DP , in 27 (42 %) of them was diagnosed the comorbid thyroid pathology, in 37 (58 %) it was absent. All patients were divided into two groups: with DP in the background of type I, II DM and thyroid pathology (A) and with DP in the background of type I, II DM without thyroid pathology (B). During the examination of patients were used clinical-anamnestic, clinical-neurological, laboratory-instrumental, neurophysiological methods of examination. Pain characteristics were assessed using the McGill Pain Questionnaire (MPQ). Statistic calculation was done in MS Excel 2003 and using the package for statistical analysis STATISTICA 10. Results. In patients of both groups comorbidly were dominated diseases of the cardiovascular system, in group A, increasingly was revealed gastrointestinal pathology. Polyneuritic disorders of sensitivity and autonomic-trophic disorders are more common in persons of group B, they have a higher frequency of comorbid pathology and longer duration of DM. In group A lack of Achilles and knee reflexes was recorded more often than in comparison group. In 18 (65 %) of the examined persons of group A was detected a fatty liver dystrophy by ultrasound scanning of the abdominal organs, which exceeds the number in group B – 13 (35 %). There is an inverse average dependence between the level of TSH and BMI (correlation coefficient = –0,65). The general index of pain rating (Pain Rating Index – PRI) in group A is higher (30,62±2,64 scores). Conclusions. Among the thyroid diseases in the examined patients of group A hypothyroidism was most often detected, so 30 % of patients had a pronounced violation of lipid metabolism in the form of obesity, besides, in this group the number of people with type II DM was prevailed. The influence of thyroid pathology on the manifestations of DP is reflected in the intensification of neuropathic pain syndrome. There is also a significant effect on the metabolism of fats and carbohydrates, which aggravate and sometimes deepen the somatic condition of the patient.

Insulin resistance and pancreatic β cell dysfunction are associated with thyroid hormone functions: A cross-sectional hospital-based study in Turkey

BACKGROUND AND AIMS

The prevalence of thyroid disease in diabetic patients is significantly higher than the general population. This indicates a possible interaction between thyroid functions and insulin sensitivity. This study aimed to investigate the relationship between insulin resistance (IR), pancreatic β cell function, and thyroid function tests.

METHODS

This cross-sectional study was conducted with adults who applied to Eskişehir Osmangazi University Hospital for general control. Fasting insulin, glucose, TSH, fT3, and fT4 levels in the serum of 1340 adult (18-60 aged) patients without any chronic diseases were examined retrospectively. The fT3/fT4 ratio, Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), and HOMA-β values were calculated. The correlation between HOMA-IR and HOMA-β values with thyroid function tests and differences between hormone levels of patients with and without IR were evaluated.

RESULTS

There was a positive correlation between HOMA-IR and TSH, negative with fT4. Also, a positive correlation between HOMA-β and fT3, negative correlation with fT4 were observed. In the IR group, fT3 levels were found significantly higher and fT4 levels were significantly lower. TSH levels were higher in the IR group but not statistically significant. The fT3/fT4 ratio was found significantly higher in the IR group and was correlated positively with both HOMA-IR and HOMA-β.

CONCLUSION

Our results revealed that thyroid dysfunction prevalence is quite high in adults who have not yet been diagnosed with diabetes but have insulin resistance and the onset of pancreatic β cell dysfunction.

Correlation of plasma metabolites with glucose and lipid fluxes in human insulin resistance

OBJECTIVE

Insulin resistance develops prior to the onset of overt type 2 diabetes, making its early detection vital. Direct accurate evaluation is currently only possible with complex examinations like the stable isotope-based hyperinsulinemic euglycemic clamp (HIEC). Metabolomic profiling enables the detection of thousands of plasma metabolites, providing a tool to identify novel biomarkers in human obesity.

DESIGN

Liquid chromatography mass spectrometry-based untargeted plasma metabolomics was applied in 60 participants with obesity with a large range of peripheral insulin sensitivity as determined via a two-step HIEC with stable isotopes [6,6-2H2]glucose and [1,1,2,3,3-2H5]glycerol. This additionally enabled measuring insulin-regulated lipolysis, which combined with metabolomics, to the knowledge of this research group, has not been reported on before.

RESULTS

Several plasma metabolites were identified that significantly correlated with glucose and lipid fluxes, led by plasma (gamma-glutamyl)citrulline, followed by betaine, beta-cryptoxanthin, fructosyllysine, octanylcarnitine, sphingomyelin (d18:0/18:0, d19:0/17:0) and thyroxine. Subsequent machine learning analysis showed that a panel of these metabolites derived from a number of metabolic pathways may be used to predict insulin resistance, dominated by non-essential amino acid citrulline and its metabolite gamma-glutamylcitrulline.

CONCLUSION

This approach revealed a number of plasma metabolites that correlated reasonably well with glycemic and lipolytic flux parameters, measured using gold standard techniques. These metabolites may be used to predict the rate of glucose disposal in humans with obesity to a similar extend as HOMA, thus providing potential novel biomarkers for insulin resistance.

A Study of Association of Thyroid Dysfunctions in Patients with Type 2 Diabetes Mellitus

Background: Type 2 diabetes mellitus is known to be associated with other endocrine dysfunctions and thyroid is one of them. In the current study we tried to evaluate the frequency of thyroid dysfunctions in patients with type 2 diabetes mellitus and compare them with a normal control population. Methods: This cross-sectional study was carried out in the Department of Physiology and Department of General Medicine, Kakatiya Medical College, and MGM Hospital, Warangal, India. A total of 50 consecutive patients with diabetes mellitus type 2 were selected as cases, and an equal number of age- and sex-matched individuals with normoglycemia as controls. Laboratory investigations included measurements of fasting blood sugar [FBS] and HbA1c values after overnight fasting for eight hours, serum triglycerides, along with serum TSH, FT3, and FT4, which were measured by chemiluminescence immunoassay. Results: Among all cases of type 2 diabetes mellitus, eight (16%) presented thyroid disorders, with 10% in male patients and 6% in female patients. The overall frequency of thyroid disorders was found in four (8%) cases, of which two (4%) in males and two in females. The values of TSH μIU/ml and FBS mg/dl in type 2 diabetes mellitus cases were plotted and a Pearson correlation coefficient of +0.70 was calculated, indicating a positive correlation between the TSH and FBS. Along with TSH levels, the values of HbA1c were plotted in patients with type 2 diabetes mellitus and a Pearson correlation coefficient of +0.76 was calculated. Conclusion: Within the limitations of the present study, it can be concluded that the prevalence of thyroid dysfunctions is more common in patients with type 2 diabetes mellitus. Also, a continuous positive correlation of TSH with FBS and HbA1c was found. Hence, a periodic screening for their coexistence in thyroid dysfunctions among diabetic patients is advisable.

Correlation Between Insulin Levels and Thyroid Hormones in Diabetic Animals After Caffeine Consumption Associated with Exercise

Introduction:

Thyroid hormones (TH) are important determinants of glucose homeostasis, and in contrast, insulin is the first hormone responsible for glycemic control.

Objective:

The objective of the present study was to correlate the levels of insulin and thyroid hormones in diabetic animals after caffeine consumption associated with physical exercise.

Methods:

A total of 48 animals, 60 days old were allocated in eight experimental groups: Control, Diabetic, Exercise, Diabetes + exercise, Caffeine, Diabetes + Caffeine, Caffeine + Exercise, and Diabetes + Exercise + Caffeine. Diabetes model was induced by intraperitoneal administration of 120 mg/kg of alloxan. On the test day, 6 mg/kg of caffeine was administrated 30 minutes before physical exercise. After, animals performed a 60 minutes’ session of predominantly aerobic exercise, using an overload of 6% of their body’s weight. Blood has been collected by a caudal puncture to future insulin, TSH, T3, and T4 analyses.

Results:

After caffeine treatment and training, insulin values were higher for the control groups (231%) when compared to the diabetic groups. A significant increase in plasmatic insulin concentration was found in caffeine group (95%) and Exercise+Caffeine group (56%) when compared to Control and Exercise groups. TSH values were increased for Diabetes, Diabetes+Caffeine and Diabetes+ Exercise+Caffeine groups (30%) compared to the other groups. A reduction in T4 values occurred in the animals of groups Diabetes+Exercise and Diabetes +Caffeine (66%) compared to the Control group. T3 values were significantly increased for the Diabetes+Exercise group (70%) when compared to the Diabetes+Exercise+Caffeine group.

Conclusion:

Physical exercise and caffeine consumption were able to promote hormonal changes in diabetic animals after 30 days of training. The study showed a reduction in the serum concentration of thyroid hormones, but insulin levels were higher.

Relationship between Free Thyroxine and Islet Beta-cell Function in Euthyroid Subjects

Thyroid hormones have a specific effect on glucose-induced insulin secretion from the pancreas. We aimed to investigate the association between euthyroid hormones and islet beta-cell function in general population and non-treated type 2 diabetes mellitus (T2DM) patients. A total of 5089 euthyroid participants (including 4601 general population and 488 non-treated T2DM patients) were identified from a cross-sectional survey on the prevalence of metabolic diseases and risk factors in East China from February 2014 to June 2016. Anthropometric indices, biochemical parameters, and thyroid hormones were measured. Compared with general population, non-treated T2DM patients exhibited higher total thyroxine (TT4) and free thyroxine (FT4) levels but lower ratio of free triiodothyronine (T3):T4 (P<0.01). HOMA-β had prominently negative correlation with FT4 and positive relationship with free T3:T4 in both groups even after adjusting for age, body mass index (BMI) and smoking. When analyzed by quartiles of FT4 or free T3:T4, there were significantly decreased trend of HOMA-β going with the higher FT4 and lower free T3:T4 in both groups. Linear regression analysis showed that FT4 but not FT3 and free T3:T4 was negatively associated with HOMA-β no matter in general population or T2DM patients, which was independent of age, BMI, smoking, hypertension and lipid profiles. FT4 is independently and negatively associated with islet beta-cell function in euthyroid subjects. Thyroid hormone even in reference range could play an important role in the function of pancreatic islets.

Nutritional status and follicular-derived thyroid cancer: An update

The incidence of differentiated thyroid cancer has been increasing in the last decades all over the world. Such a steady growth cannot be entirely attributable to more intensive thyroid nodule screening and more sensitive diagnostic procedures. Several environmental factors have changed with sufficient rapidity in the same time frame and may represent credible candidates for this increase. They include modified iodine intake, lifestyle-associated risk factors, exposure to various toxic compounds, pollutants and xenobiotics, nutritional deficiencies, eating habits and comorbidities. Foremost, nutritional patterns have gained high interest as possible promoters and modifiable risk factors for thyroid cancer in recent years. The aim of this narrative review is to focus on the relationship between thyroid cancer and nutritional factors, dietary habits and obesity. Low iodine intake has been associated to increased risk of thyroid cancer, favoring the development of more aggressive histotypes. Moreover, correction of iodine deficiency can shift thyroid cancer subtypes toward less aggressive forms, without affecting the overall risk for cancer. Actually, evidence regarding the association between selenium and vitamin D deficiency and thyroid cancer is very limited, despite their well-known anti-cancer potentials, and the clinical usefulness of their supplementation is still uncertain in this setting. Albeit the relationship between single foods and thyroid cancer is difficult to examine, fish and iodine-rich foods, vegetables, and fruits might exert protective effects on thyroid cancer risk. Conversely, no clear association has been found for other foods to date. Lastly, a clear association between obesity and the risk of thyroid cancer, with more aggressive behavior, seems to emerge from most studies, likely involving variations in thyroid function and chronic inflammation mediated by cytokines, insulin, leptin and adiponectins. Although no definite association between dietary factors and thyroid cancer has been firmly established so far, some nutritional patterns, together with excessive weight, seem to play a relevant role in thyroid cancer carcinogenesis as well as in its severity and aggressiveness. These effects may play an additive role to the well-established one exerted by environmental carcinogens, such as pollutants and radiation exposure.

Higher thyroid-stimulating hormone levels in the first trimester are associated with gestational diabetes in a Chinese population

AIM

To evaluate the relationship between maternal thyroid-stimulating hormone levels during the first trimester and gestational diabetes risk.

METHODS

In Tianjin, China, 7258 women underwent a thyroid-stimulating hormone screening test within 12 gestational weeks and then had a glucose challenge test at 24-28 weeks of gestational age. The women with a glucose challenge test ≥7.8 mmol/l underwent a 75 g oral glucose tolerance test. Gestational diabetes was diagnosed following International Association of Diabetes and Pregnancy Study Group criteria. Restricted cubic spline analysis was performed to explore full-range risk associations of thyroid-stimulating hormone levels with gestational diabetes. Logistic regression was performed to obtain odds ratios and 95% confidence intervals.

RESULTS

In all, 594 women (8.2%) had gestational diabetes. Among women with thyroid-stimulating hormone ≤3.2 mIU/l, a positive association between thyroid-stimulating hormone levels and gestational diabetes risk was found (adjusted OR: 1.13, 95% CI: 1.00-1.27). There was no relationship between thyroid-stimulating hormone levels and gestational diabetes risk in univariable and multivariable analyses among women with thyroid-stimulating hormone >3.2 mIU/l. In subgroup analyses, among women with thyroid-stimulating hormone ≤3.2 mIU/l and BMI ≥25 kg/m² , the adjusted odds ratio for thyroid-stimulating hormone levels with gestational diabetes was enhanced to 1.25 (95% CI: 1.02-1.53).

CONCLUSIONS

In pregnant Chinese women, thyroid-stimulating hormone levels even within normal range in the first trimester were positively related to gestational diabetes risk, especially for pre-pregnancy overweight/obese women.

Association Between Glycaemic Control and the Intake of Thiazide Diuretics, Beta Blockers and Levothyroxine in People Without Diabetes

OBJECTIVE

The pharmacological additional information for many medications includes warnings stating that the blood sugar control may be worsened by the intake of certain drugs. However a quantification of the effects is missing. This may result in confusion for patients as well as for their physicians. The aim of this study was to assess a potential association between medication (beta blockers, thiazides, levothyroxine) and HbA_1c in people without diabetes.

METHODS

In this cross-sectional study we analysed data from 2 921 people (7 699 visits) without diabetes (age 46.6 y; 69.1% women; BMI 27.6±6.4 kg/m²; HbA_1c 5.2%) who had at least one HbA_1c determination and a complete documentation of their drug intake. An oral glucose tolerance test was not performed. The participants were divided in 8 groups (no regular drug intake, levothyroxine alone, beta blockers alone, thiazides alone, combination 2 of 3, combination of all 3). Patients with known distorting influences of the HbA_1c were excluded.

RESULTS

People with no regular drug intake had an HbA_1c of 5.4% [35.8 mmol/mol]. The HbA_1c of the group that took all 3 drugs in combination was 5.6% [38.2 mmol/mol]. A multiple linear mixed model showed an increase in HbA_1c for thiazides (β=0.0558, p=0.025) and a decrease for combination of levothyroxine and thiazide (β=-0.0765, p=0.010).

CONCLUSION

Thiazides and the combination of levothyroxine and thiazides were associated with slight changes in HbA_1c. In this study there was no association between the intake of beta blockers and HbA_1c. At least for people without diabetes these effects seem to be of minor importance.

Thyroid dysfunction prevalence and relation to glycemic control in patients with type 2 diabetes mellitus

OBJECTIVE

It is usually difficult to clinically identify thyroid abnormalities in diabetics as features of thyroid dysfunction may simulate diabetes symptoms or complications. So, assessing thyroid dysfunction prevalence in patients with type 2 diabetes mellitus (DM) would help better control of DM and its complications. Several studies reported this prevalence, however, some included small sample size or lacked a control group. We aimed to determine thyroid dysfunction prevalence in diabetic patients as well as its relation to glycemic control.

METHODS

A cross-sectional study included 200 patients having type 2 DM and 200 apparently healthy controls. Each participant was tested for fasting and 2-h post-prandial blood glucose, glycated haemoglobin (HbA1C), thyroid function tests: thyroid-stimulating hormone (TSH), free tri-iodothyronine (FT3), free thyroxine (FT4), serum total cholesterol and triglycerides and thyroid antibodies; anti-thyroid peroxidase (anti-TPO) and anti-thyroglobulin (anti-Tg) for hypothyroidism only.

RESULTS

There was a significant increase in serum TSH and T3 levels in diabetics when compared with the controls, (P < 0.001, P = 0.001), respectively. Thyroid dysfunction was significantly more prevalent in patients with HbA1c ≥ 8%, (P = 0.0001), and in those having longer diabetes duration, (P < 0.001).

CONCLUSION

There was a higher prevalence of thyroid dysfunction among patients with type 2 DM. This dysfunction increased with the rise of HbA1c. This could suggest that poor glycemic control may have a role in the development of thyroid dysfunction in type 2 DM patients. Subclinical hypothyroidism was the most prevalent type of thyroid dysfunction in diabetic patients.

Effects of Maternal Flaxseed Supplementation on Female Offspring of Diabetic Rats in Serum Concentration of Glucose, Insulin, and Thyroid Hormones

Objective: This study aimed to evaluate the effect of maternal consumption of flaxseed flour and oil on serum concentrations of glucose, insulin, and thyroid hormones of the adult female offspring of diabetic rats. Methods: Wistar rats were induced to diabetes by a high-fat diet (60%) and streptozotocin (35 mg/kg). Rats were mated and once pregnancy was confirmed, were divided into the following groups: Control Group (CG): casein-based diet; High-fat Group (HG): high-fat diet (49%); High-fat Flaxseed Group (HFG): high-fat diet supplemented with 25% flaxseed flour; High-fat Flaxseed Oil group (HOG): high-fat diet, where soya oil was replaced with flaxseed oil. After weaning, female pups (n = 6) from each group were separated, received a commercial rat diet and were sacrificed after 180 days. Serum insulin concentrations were determined by ELISA, the levels of triiodothyronine (T3), thyroxine (T4) and thyroid-stimulating hormone (TSH) were determined by chemiluminescence. Results: There was a significant reduction in body weight at weaning in HG (-31%), HFG (-33%) and HOG (44%) compared to CG (p = 0.002), which became similar by the end of 180 days. Blood glucose levels were reduced in HFG (-10%, p = 0.044) when compared to CG, and there was no significant difference between groups in relation to insulin, T3, T4, and TSH after 180 days. Conclusions: Maternal severe hyperglycemia during pregnancy and lactation resulted in a microsomal offspring. Maternal consumption of flaxseed reduces blood glucose levels in adult offspring without significant effects on insulin levels and thyroid hormones.

Thyroid-stimulating hormone levels in the normal range and incident type 2 diabetes mellitus

AIM

To evaluate the relationship between thyroid-stimulating hormone (TSH) levels within the normal range and the risk of type 2 diabetes mellitus (T2DM) in a cohort of patients at high cardiovascular risk, and to perform a systematic review and meta-analysis of previous studies.

METHODS

We included 5542 patients without T2DM from the prospective Secondary Manifestations of ARTerial disease study with TSH levels between 0.35 and 5.0 mIU/L without anti-thyroid medication or thyroid-hormone replacement therapy. Cox regression was used to investigate the relationship between baseline plasma TSH levels and incident T2DM. MEDLINE, EMBASE, and Cochrane were searched for prospective cohorts assessing TSH and incident T2DM. Hazard ratios (HR) from included prospective cohort studies were pooled using a random-effects model.

RESULTS

In patients at high cardiovascular risk, higher plasma TSH levels in the normal range were not associated [HR 1.07 per mIU/L increase in TSH (95% confidence interval (95% CI) 0.95-1.22)] with an increased risk of T2DM, adjusted for age, sex, smoking, total and HDL cholesterol, and triglycerides. In the meta-analysis involving three prospective cohort studies, including the present study, including 29,791 participants with 1930 incident events, there was no relation between plasma TSH levels in the normal range and incident T2DM [pooled HR 1.06 (95% CI 0.99-1.14)].

CONCLUSION

There is no apparent relation between plasma TSH levels in the normal range and incident T2DM in patients at high cardiovascular risk.

Bone Marrow-Derived Mesenchymal Stem Cells Ameliorate the Pancreatic Changes of Chemically Induced Hypothyroidism by Carbimazole in Male Rats

We induced hypothyroidism (HT) in male rats through chronic oral administration of carbimazole and then tested whether an i.v. injection of rat bone marrow-derived mesenchymal stem cells (BM-MSCs) could ameliorate the HT-induced changes in pancreatic structure and function. The thyroid and pancreatic function tests, as well as total antioxidant capacity (TAC) and malondialdehyde (MDA) were estimated. The pancreatic structure was evaluated by hematoxylin and eosin (H&amp;E) stain. Insulin protein and cleaved caspase-3 were detected immunohistochemically. The degree of apoptosis was assessed by TUNEL assay. The morphometric measurements were done by an image analyzer system and the obtained data were statistically analyzed. HT rats showed hyperglycemia associated with insulin deficiency, decreased TAC and increased MDA levels. H&amp;E-stained sections showed that the pancreatic septa were infiltrated with acidophilic material. Some acini were vacuolated while others showed depleted acidophilia and dilated lumina. Spindle-shaped cells were accumulated within deformed islets in HT rats. The positive reaction with anti-cleaved caspase-3 was exclusively noted in the cytoplasm of islet cells with no immunostaining reaction in the acinar and ductal cells, whereas the positively stained nuclei with TUNEL were demonstrated in the islet and acinar cells. A significant increase in the apoptotic index % of both markers was detected. Injection of BM-MSCs in HT rats restored all biochemical indicators of disturbed pancreatic function to normal level and improved pancreatic structure, resulting in a clear septa and normal appearance of acini and islets. In conclusion, many of the significant structural and func tional pancreatic alterations detected in HT rats were ameliorated after the injection of BM-MSCs. These data demonstrate the ability of BM-MSCs to repair pancreatic disturbances. Further studies on humans are necessary to determine the potential clinical applications of BM-MSCs.

Isolated effect of maternal thyroid-stimulating hormone, free thyroxine and antithyroid peroxidase antibodies in early pregnancy on gestational diabetes mellitus: a birth cohort study in China

This article aims to understand the isolated effect of maternal thyroid-stimulating hormone (TSH), free thyroxine (FT₄) and antithyroid peroxidase antibodies (TPOAb) in early pregnancy on gestational diabetes mellitus (GDM). Based on a birth cohort, pregnant women presented to maternity hospitals for the first antenatal care from Nov 2008 to Oct 2010 were invited to participate in the study. A self-administered questionnaire was asked to complete to collect data on socio-economic variables, previous adverse pregnancy outcomes, method of conception, previous endocrinic and metabolic diseases, and pregnancy-related anxiety in 1^st trimester of the index pregnancy. Pre-pregnancy BMI was measured. Serum samples were collected, and TSH, FT₄ and TPOAb were assayed. GDM was confirmed from medical records screened on 24-28 gestational weeks by using oral glucose tolerance test (OGTT). The prevalence of isolated subclinical hypothyroidism, hypothyroidemia and positive TPOAb in early pregnancy was 2.0%, 2.0% and 12.8%. Prevalence of GDM in women with the isolated sub-clinical hypothyroidism, hypothyroxinemia and positive TPOAb was 2.9%, 2.8% and 3.1%, respectively, which were all higher than that detected in euthyroidism women (1.2%). Women with isolated positive TPOAb had significantly higher TSH and lower FT₄ level compared with euthyroidism women. It was found that isolated positive TPOAb in early pregnancy increased the risk of GDM, adjusted RR and 95%CI being 2.541(1.037-6.226). No significant relationships were identified between isolated sub-clinical hypothyroidism or hypothyroxinemia with GDM. In conclusion, isolated thyroid autoimmunity, represented by positive TPOAb, in early pregnancy were associated with GDM independent of TSH and FT₄.

Biochemical isthmus [nexus] between type 2 diabetes mellitus and thyroid status-an update

Both Type 1 [T1DM] and Type 2 diabetes mellitus [T2DM] share a nexus with altered thyroid status. In recent times, evidences point to the link between thyroid hormones andT2DM in particular. Several lines of evidences suggest an array of biochemical and molecular events. Gene polymorphism, disturbances in gene expression and regulation, enhanced and bizarre absorption of dietary glucose from intestine, decreased utilization of glucose by tissues and aberrations in hepatic handling of glucose with the onus on Gluconeogenesis are some of the projected mechanisms. Insulin resistance, a progressive condition is the hallmark in T2DM. Hypothyroidism as well as hyperthyroidism have been associated with insulin resistance which are synonymous with impaired glucose metabolism in T2DM. A multitude of basic, clinical and molecular studies provide an insight into thyroid comorbidity in T2DM, though there are a few instances to suggest equivocal link denoting cause-effect relationship. In biochemical pharmacology, as fortified by pharmacogenomics, modalities have now been proposed, through drug trials, to underline the utility of specifically designed thyroid hormone analogues in addressing metabolic syndrome, DM and associated cardiovascular pathology. A thorough understanding of the physiological, biochemical and molecular mechanisms would certainly open newer vistas in the perspectives of T2DM with special reference to alterations in thyroid status.

Impaired Sensitivity to Thyroid Hormones Is Associated With Diabetes and Metabolic Syndrome

OBJECTIVE

Diabetes prevalence and incidence increase among individuals with hypothyroidism but also among those with hyperthyroxinemia, which seems contradictory. Both high free thyroxine (fT4) and high thyroid-stimulating hormone (TSH) are present in the resistance to thyroid hormone syndrome. A mild acquired resistance to thyroid hormone might occur in the general population and be associated with diabetes. We aimed to analyze the association of resistance to thyroid hormone indices (the Thyroid Feedback Quantile-based Index [TFQI], proposed in this work, and the previously used Thyrotroph T4 Resistance Index and TSH Index) with diabetes.

RESEARCH DESIGN AND METHODS

We calculated the aforementioned resistance to thyroid hormone indices based on a U.S. representative sample of 5,129 individuals ≥20 years of age participating in the 2007-2008 National Health and Nutrition Examination Survey (NHANES). Also, to approximate TFQI, a U.S.-referenced Parametric TFQI (PTFQI) can be calculated with the spreadsheet formula =NORM.DIST(fT4_cell_in_pmol_per_L,10.075,2.155,TRUE)+NORM.DIST(LN(TSH_cell_in_mIU_per_L),0.4654,0.7744,TRUE)-1. Outcomes of interest were glycohemoglobin ≥6.5%, diabetes medication, diabetes-related deaths (diabetes as contributing cause of death), and additionally, in a fasting subsample, diabetes and metabolic syndrome. Logistic and Poisson regressions were adjusted for sex, age, and race/ethnicity.

RESULTS

Odd ratios for the fourth versus the first quartile of TFQI were 1.73 (95% CI 1.32, 2.27) (P _trend = 0.002) for positive glycohemoglobin and 1.66 (95% CI 1.31, 2.10) (P _trend = 0.001) for medication. Diabetes-related death rate ratio for TFQI being above versus below the median was 4.81 (95% CI 1.01, 22.94) (P _trend = 0.015). Further adjustment for BMI and restriction to normothyroid individuals yielded similar results. Per 1 SD in TFQI, odds increased 1.13 (95% CI 1.02, 1.25) for diabetes and 1.16 (95% CI 1.02, 1.31) for metabolic syndrome. The other resistance to thyroid hormone indices showed similar associations for diabetes-related deaths and metabolic syndrome.

CONCLUSIONS

Higher values in resistance to thyroid hormone indices are associated with obesity, metabolic syndrome, diabetes, and diabetes-related mortality. Resistance to thyroid hormone may reflect energy balance problems driving type 2 diabetes. These indices may facilitate monitoring treatments focused on energy balance.

Jinlida Granules Improve Dysfunction of Hypothalamic-Pituitary-Thyroid Axis in Diabetic Rats Induced by STZ

Objective

We aim to explore the effects and mechanisms of Jinlida granules on the dysfunction of hypothalamic-pituitary-thyroid (HPT) axis in diabetic rats induced by streptozotocin.

Methods

A total of 48 SD rats were randomized into normal control group (NC, n = 6) and diabetic group (n = 42). Rats in diabetic group were randomly divided into diabetes mellitus (DM) control group, low, medium, and high doses of Jinlida group (JL, JM, and JH), medium dose of Jinlida plus Tongxinluo group (JM + T), metformin group (Met), and Saxagliptin group (Sax) (n = 6 in each group). Diabetic rats were obtained by intraperitoneal injection of streptozotocin and sacrificed at 8 weeks to examine the function of HPT axis.

Results

Levels of fasting blood glucose (P < 0.05), pIκB, TNFα (P < 0.05), pNF-κB, and IL-6 (P < 0.01) in liver tissue and TSHR mRNA expression (P < 0.01) in diabetic group were significantly increased, while levels of serum T3 and T4, thyroid hormone receptor (TR) mRNA and Dio1 mRNA in liver tissue, and sodium iodide symporter (NIS) mRNA in thyroid tissue in diabetic group were significantly decreased compared with those in NC group (P < 0.01). Among diabetic groups, level of fasting blood glucose in JH, JM + T and Met group was lower (P < 0.05) compared with DM group. However, levels of serum T3 and T4, TR mRNA in liver tissue, TSHR, and NIS mRNA in thyroid tissue in JH, JM + T, Met, and Sax group were significantly increased (P < 0.01) compared to DM group. In contrast, levels of Dio1 mRNA, pI-κB in Met and JM + T groups, pNF-κB in JH, JM + T, and Met group, and TNFα and IL-6 in JM, JH, JM + T, and Met group were significantly decreased (P < 0.05). HE staining showed reduced thyroid follicular epithelium and follicular area, as well as increased colloid area in DM group, indicating impaired synthesis, reabsorption, and secretory of TH in diabetes, which was significantly improved in JH, JM + T, and Met groups.

Conclusion

HPT axis dysfunction in DM could be significantly improved by Jinlida granules. The mechanism might be associated with the anti-inflammatory effects involving NF-κB pathway. Our findings suggested the potential benefit of Jinlida granules for patients with HPT axis dysfunction and DM, which was to be verified by more experimental and clinical studies.

Thyroid function is associated with body mass index and fasting plasma glucose in Thai euthyroid population

AIMS

Several population-based studies found the associations between body mass index and thyroid function within the normal range. Furthermore, these thyroid functions are related with insulin resistance and plasma glucose levels. This study aimed to investigate the associations between thyroid functions and metabolic parameters in Thai euthyroid population.

METHODS

Participants from the Thai National Thai Health Examination Survey were randomly measured for TSH, FT4, anti-thyroperoxidase, and anti-thyroglobulin. Euthyroidism was defined by TSH 0.27-4.20 mIU/L and FT4 0.93-1.71 ng/dL.

RESULTS

A total of 2242 euthyroid participants were included. Fifty-one percent were female. Mean age, fasting plasma glucose, and body mass index were 55 ± 21 years, 93 ± 29 mg/dL, and 23.4 ± 4.6 kg/m², respectively. Multivariate regression analysis after age and sex adjustment showed a negative association of serum FT4 with body mass index (β = -0.070, p = 0.001) and the relationship was still significant after subjects with positive anti-thyroperoxidase were excluded (β = -0.068, p = 0.003). In contrast, serum TSH was positively associated with body mass index (β = 0.052, p = 0.012). Moreover, serum FT4 was positively associated with fasting plasma glucose levels (β = 0.097, p < 0.001).

CONCLUSIONS

Small variations of serum TSH and FT4 within the reference range may contribute to the differences in metabolic indexes such as body mass index and fasting plasma glucose.

Construction of a long non‑coding RNA-mediated competitive endogenous RNA network reveals global patterns and regulatory markers in gestational diabetes

Gestational diabetes mellitus (GDM) is a common disease affecting pregnant women. Recent studies have suggested that competing endogenous RNAs (ceRNAs), which compete with long non‑coding RNAs (lncRNAs) for microRNA (miRNA or miR) binding and indirectly regulate miRNA targets through competing interactions, play a critical role in disease. In this study, we present a computationally integrated approach with which to construct a lncRNA‑mediated ceRNA network (LCEN) in GDM by integrating RNA interactions and expression data. lncRNAs exhibited specific features and played critical roles in GDM‑associated LCEN. The construction of a global functional score profile revealed that ceRNAs had a high activity in GDM. We extracted several ceRNA modules and demonstrated that these modules had increased close interactions. We further discovered that these ceRNA modules may be utilized as specific and effective circulating biomarkers for GDM. Finally, functional analyses demonstrated that the GDM‑associated ceRNAs participated in the regulation of irisin and the thyroid hormone signaling pathway. It was suggested that there were close associations between the thyroid hormone and GDM. Collectively, ceRNAs may accelerate biomarker discovery and therapeutic development in GDM.

Moderating effects of sleep duration on diabetes risk among cancer survivors: analysis of the National Health Interview Survey in the USA

Background

Growing evidence suggests that cancer and diabetes may share common risk factors such as age, race/ethnicity, obesity, insulin resistance, sedentary lifestyle, smoking, and alcohol consumption. However, little is known about how habitual sleep duration (a known cardiometabolic risk factor) may affect the relationship between cancer and diabetes. The aim of this study was to investigate whether sleep duration moderated the relationship between history of cancer and diabetes.

Methods

Data were extracted from the National Health Interview Survey dataset from 2004 to 2013 containing demographics, chronic diseases, and sleep duration (N=236,406). Data were analyzed to assess the moderating effect of short and long sleep durations on cancer and diabetes mellitus.

Results

Our findings indicate that short sleep (odds ratio [OR] =1.07, 95% CI =1.03–1.11, P<0.001) and long sleep (OR =1.32, 95% CI =1.26–1.39, P<0.001) were associated with diabetes mellitus in fully adjusted models. However, only long sleep duration significantly moderated the relationship between cancer and diabetes (OR =0.88, 95% CI =0.78–0.98, P<0.05).

Conclusion

Our findings indicate that for cancer survivors, short sleep was associated with higher self-reported diabetes and long sleep duration may act as a buffer against diabetes mellitus, as the likelihood of self-reported diabetes was lower among cancer survivors who reported long sleep duration.

Impact

Findings from the current study have clinical and public health implications. Clinically, comprehensive sleep assessments and sleep interventions to improve sleep are needed for cancer survivors who have comorbid diabetes. Our findings can also spur public health reform to make sleep an important component of standard cancer survivorship care, as it reduces other chronic disease like diabetes.

Evaluation of thyroid function in type 2 diabetes in north-eastern part of India: A hospital-based study

Background

Diabetes mellitus (DM) and thyroid dysfunctions are the two most common endocrine disorders to come across in any clinical practice. Both thyroid hormones and insulin act antagonistically in metabolic pathways or cycles of cells. The aim of our study is to look for thyroid dysfunction in patients with type 2 DM and its correlation with insulin resistance (IR).

Methods

A cross-sectional study was carried out among 80 newly diagnosed type 2 diabetic patients. Thyroid-stimulating hormone (TSH), free triiodothyronine, free thyroxine, and insulin were measured in fasting serum sample. Homeostasis model assessment for IR was calculated as per formula.

Results

Among 80 diabetic patients, 20 were hypothyroid, 4 were hyperthyroid, and 56 were found to be euthyroid. IR was found to be significantly higher in hypothyroid as compared to euthyroid patients. A positive association was found between TSH and IR (r = 0.230) among hypothyroid patients though association was not significant. In hyperthyroid patients, a strong negative correlation (r = -0.94933) was found between TSH and IR, but no association was found among euthyroid patients.

Conclusion

The inability to recognize the presence of thyroid hormone dysfunction may be one of the important causes of poor management of type 2 DM. Therefore, there is a need for routine assay of thyroid hormones in type 2 diabetic patients to improve the medical management as well as to reduce the morbidity in them.

Low total and free triiodothyronine levels are associated with insulin resistance in non-diabetic individuals

This study examined associations of thyroid hormone levels and insulin resistance (IR) in non-diabetic individuals. Using a cross-sectional design, 2007-2008 data from the National Health and Nutrition Examination Survey (NHANES) were analyzed. NHANES participants ≥20 years of age with complete data of interest were included. The homeostatic model assessment (HOMA) was used to quantify IR, and treated as a continuous variable. Self-reported diabetes or a fasting glucose ≥7 mmol/L were used as criteria to exclude diabetic subjects. Race, liver function, obesity, hypertension, dyslipidemia, smoking, physical activity, vigorous recreational activity, 2-hour glucose, hemoglobin A1C (HbA1C), high-density lipoprotein, triglyceride, vitamin D and C-reactive protein were covariates significantly associated with HOMA-IR. A total of 1,560 non-diabetic subjects were included in the analysis. When adjusted for all factors significant in the univariate analysis (race, liver function, obesity, hypertension, dyslipidemia, smoking, physical activity, vigorous recreational activity, 2-hour glucose, HbA1C, high-density lipoprotein, triglyceride, vitamin D, and CRP) low total triiodothyronine (TT3) and low free T3 (FT3) were significantly associated with decreased HOMA-IR (adjusted coefficient = -0.486, 95% confidence interval [CI]: -0.936, -0.036; adjusted coefficient = -1.151, 95% CI: -1.952, -0.350, respectively). Insulin resistance is associated with low thyroid hormone levels in non-diabetic individuals.

Association between thyroid hormones and the components of metabolic syndrome

BACKGROUND

Thyroid hormones are known to have direct and indirect effects on metabolism. Individuals with metabolic syndrome, a disease that is growing in incidence at a rapid rate, are at higher risk for cardiovascular disease, diabetes, and cancer. The aim of this study was to identify whether significant correlations exist between thyroid hormone levels and components of the metabolic syndrome in the general population of Korea.

METHODS

The data were collected from the sixth Korea National Health and Nutrition Examination Surveys from 2013 to 2015. A total of 1423 participants were tested for thyroid function. The analysis of variance and multiple linear regression were performed to analyze the relationship between thyroid hormone level and components of the metabolic syndrome.

RESULTS

A positive association between free thyroxine and fasting glucose level was observed in patients with high free thyroxine levels (≥1.70 ng/dL, β = 15.992, p = < 0.0001), when compared with patients with normal-middle free thyroxine levels. Moreover, a negative association was observed between free thyroxine and triglyceride levels in patients with normal-high free thyroxine levels (β = - 21.145, p = 0.0054) and those with high free thyroxine levels (β = - 49.713, p = 0.0404).

CONCLUSION

Free thyroxine shows a partially positive association with fasting glucose and a partially negative association with triglycerides in the Korean population. In patients with abnormal thyroid function, follow up tests for glucose levels and lipid profiling during treatment for thyroid dysfunction would be beneficial in terms of overlooking metabolic syndrome and to prevent related diseases.

Diabetes mellitus and thyroid diseases

Both diabetes mellitus and thyroid diseases are very common in the fields of endocrinology and metabolism. Coexistence of diabetes mellitus and thyroid diseases are frequently experienced. However, higher prevalence of thyroid dysfunction in both type 1 and type 2 diabetes compared with non-diabetics have been reported. Autoimmunity is a key to understand the link between type 1 diabetes and autoimmune thyroid diseases. And, this combination of autoimmune diseases is recognized as autoimmune polyglandular syndrome type 3 variant. On the other hand, the relation between thyroid function and glucose intolerance or type 2 diabetes mellitus is more complicated. Both hyperthyroidism and hypothyroidism could be risk factors for glucose intolerance. In this review, current knowledge about the relationship between diabetes mellitus and thyroid diseases is described, which includes the following topics: effects of thyroid hormone on glucose metabolism, subclinical hypothyroidism and diabetic complications, type 1 diabetes and autoimmune thyroid diseases, and several clinical pitfalls in patients with both diseases.

Thyroid-Stimulating Hormone Levels Are Positively Associated with Insulin Resistance

BACKGROUND It has been reported that overt and mild thyroid dysfunctions are associated with insulin resistance (IR). We performed this retrospective study to evaluate the relationships between thyroid-stimulating hormone (TSH) levels within the reference range and IR. MATERIAL AND METHODS A total of 447 outpatients were enrolled in this study: 298 with type 2 diabetes mellitus and 149 nondiabetic individuals. Based on a cutoff HbA1c value of 7%, diabetic patients were additionally divided into 2 groups: a high-HbA1c group (n=240) and a low-HbA1c group (n=58). The relationships of TSH levels and HOMA-IR were computed using linear regression models. RESULTS TSH levels were positively and linearly associated with HOMA-IR in both the nondiabetic and diabetic groups (r=0.210, p=0.011 and r=0.451, p<0.001), as well as in the high- and low-HbA1c groups (r=0.507, p<0.001 and r=0.259, p=0.048). A better correlation between TSH levels and HOMA-IR was found in the diabetic group and in the high-HbA1c group when compared with the nondiabetic group and the low-HbA1c group, respectively. Linear regression analysis showed that TSH levels were independently associated with HOMA-IR (p=0.034, =0.049 and <0.001 in nondiabetic, low-, and high-HbA1c groups, respectively). CONCLUSIONS Our data suggest that TSH is independently associated with insulin resistance.

[Pharmacological approaches for correction of thyroid dysfunctions in diabetes mellitus]

Thyroid diseases are closely associated with the development of types 1 and 2 diabetes mellitus (DM), and as a consequence, the development of effective approaches for their treatment is one of the urgent problems of endocrinology. Traditionally, thyroid hormones (TH) are used to correct functions of the thyroid system. However, they are characterized by many side effects, such as their negative effect on the cardiovascular system as well as the ability of TH to enhance insulin resistance and to disturb insulin-producing function of pancreas, exacerbating thereby diabetic pathology. Therefore, the analogues of TH, selective for certain types of TH receptors, that do not have these side effects, are being developed. The peptide and low-molecular weight regulators of thyroid-stimulating hormone receptor, which regulate the activity of the thyroid axis at the stage of TH synthesis and secretion in thyrocytes, are being created. Systemic and intranasal administration of insulin, metformin therapy and drugs with antioxidant activity are effective for the treatment of thyroid pathology in types 1 and 2 DM. In the review, the literature data and the results of own investigations on pharmacological approaches for the treatment and prevention of thyroid diseases in patients with types 1 and 2 DM are summarized and analyzed.

Myopathy in hyperthyroidism as a consequence of rapid reduction of thyroid hormone: A case report

RATIONALE

Myalgia and elevated creatine kinase (CK) are occasionally observed during the treatment of hyperthyroid patients. Relative hypothyroidism resulted from rapid thyroid hormone reduction had been promoted as a plausible cause of these myopathic changes, however rarely reported.

PATIENT CONCERNS

We hereby presented a 20-year-old female with Grave's disease, who developed myopathy and elevated CK during rapid correction of thyroid hormone.

DIAGNOSES

Relative hypothyroidism-induced myopathy.

INTERVENTIONS

Antithyroid drug (ATD) dosage was reduced without levothyroxine replacement.

OUTCOMES

The muscular symptoms were recovered with CK level returned to normal after adoption of the euthyroid status.

LESSONS

Differentiation of relative hypothyroidism from other causes of myopathy, especially with the effect of ATD, is important for clinical practice, although difficult in many cases.

Association of triiodothyronine levels with future development of metabolic syndrome in euthyroid middle-aged subjects: a 6-year retrospective longitudinal study

BACKGROUND

Several cross-sectional studies have reported that thyroid hormone levels are associated with cardiovascular risk markers and metabolic syndrome (MetS) even in euthyroid subjects. However, the prognostic role of serum thyroid hormone levels in the risk of incident MetS has not been elucidated.

AIM

We aimed to investigate the associations of baseline serum thyroid hormone levels with the development of MetS in healthy subjects.

METHODS

This 6-year, cross-sectional, longitudinal and follow-up study was conducted in 12 037 euthyroid middle-aged subjects without MetS subjected to comprehensive health examinations. Subjects were grouped according to total triiodothyronine (T3) quartiles. The hazard ratio (HR) for the development of MetS according to T3 quartiles was estimated using Cox proportional hazards model.

RESULTS

During the 6-year period, 3544 incident cases of MetS (29%) were identified. The proportion of subjects with incident MetS increased across the T3 quartiles (P for trend <0.001). The HR and 95% confidence interval (CI) for the development of MetS were significantly higher in the highest T3 quartile compared with the lowest T3 quartile even after adjusting for confounding variables including gender, age and smoking (HR: 1.238, 95% CI: 1.128-1.358, P < 0.001).

CONCLUSION

In euthyroid middle-aged subjects, serum T3 levels are associated with increased risk for future development of MetS.