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

Impaired sensitivity to thyroid hormones is associated with increased body fat mass/muscle mass ratio (F/M) in the euthyroid population

OBJECTIVE

To explore the relationship between body fat mass/muscle mass ratio (F/M) and thyroid hormone sensitivity in the euthyroid population.

METHODS

Body compositions of 845 check-up individuals were determined using bioelectrical impedance analysis (BIA). Biochemical indexes including blood glucose, blood lipids, liver and kidney functions and thyrotropic hormones (THs) were detected. Free triiodothyronine to free thyroxine ratio (FT3/FT4), Thyroid Feedback Quantile-based Index (TFQI), Thyrotropin Thyroxine Resistance Index (TT4RI) and TSH Index (TSHI) were calculated for analysis.

RESULTS

TT4RI and TSHI showed increased trends with statistical difference, while FT3/FT4 and TFQI showed no difference among F/M quartile groups. After adjusting for confounding factors, F/M exhibited no correlation with FT3/FT4, but positive correlations with TFQI, TT4RI and TSHI. Gender subgroup analysis showed that F/M exhibited positive relationship with TFQI in females; exhibited positive correlations with TFQI, TT4RI and TSHI before the inflection points, but no correlations thereafter in males. Age subgroup analysis showed that F/M exhibited positive correlations with TFQI, TT4RI and TSHI, but no correlation with FT3/FT4 in age < 65 years group; exhibited no relationship with thyroid hormone sensitivity in age ≥ 65 years group. BMI subgroup analysis showed that F/M exhibited no relationship with thyroid hormone sensitivity in BMI < 25 kg/m2 group; exhibited positive correlations with TFQI, TT4RI and TSHI before the inflection points, but no correlations thereafter in BMI ≥ 25, < 30 kg/m2 group; exhibited positive correlation with TFQI before the inflection point, but no correlation thereafter in BMI ≥ 30 kg/m2 group; exhibited no correlations with TT4RI and TSHI before the inflection points, but negative correlations with them thereafter in BMI ≥ 30 kg/m2 group.

CONCLUSION

Impaired central, but not peripheral sensitivity to thyroid hormones was associated with increased body fat mass/muscle mass ratio (F/M), this association was obvious in males, individuals with age < 65 years and BMI ≥ 25 kg/m2, with different inflection points. Maybe F/M independently affects thyroid hormone sensitivity, we need more clinical and basic studies in the future.

Association Between Maternal Thyroid Hormone Concentration with Normal Thyroid Function During Pregnancy and Preschoolers' Glycolipid Metabolism: A Birth Cohort Study

Background: Thyroid hormones (THs) are essential endocrine hormones that play key roles in individual's growth and development. There is limited knowledge about the association between maternal TH concentrations variations with normal thyroid function during pregnancy and offspring's glycolipid metabolism. Methods: A total of 1130 mother-child pairs from the Ma'anshan birth cohort were included in this prospective study. Maternal TH levels and thyroid peroxidase antibodies were measured in the 1st, 2nd, and 3rd trimesters of pregnancy during the childhood follow-up period. Fasting venous blood was collected from children at 4-6 years of age and glycolipid metabolic indicators were assayed. Analyses were performed using Binary logistic regression models, linear regression models, and Generalized linear regression model. Results: Maternal TH trajectories were fitted via latent category growth models. During the 1st trimester of pregnancy, maternal T3 and free thyroxine (fT4) levels were positively associated with children's blood glucose levels (β = 0.007 [CI 0.028-0.181]; β = 0.022 [CI 0.004-0.040]), whereas high levels of fT4 may be associated with decreased risk of children's hypercholesterolemia (OR = 0.870 [CI 0.768-0.986]). Maternal T4 concentrations during the 3rd trimester of pregnancy were negatively associated with children's cholesterol levels (β = -0.002 [CI -0.003-0.00]). High maternal TH levels were associated with high fasting glucose level and low low-density lipoprotein concentrations in children. Conclusions: Maternal TH dynamic variations may be associated with glycolipid metabolism in preschoolers, even when women do not have clinically diagnosed thyroid disorders. The exact associations between maternal THs in specific trimesters of pregnancy under normal thyroid function conditions and glycolipid metabolism in offspring require further investigation.

A Retrospective Analysis of the Changes in Prediabetes-Associated Markers of Thyroid Function in Patients from Durban, South Africa

Thyroid dysfunction and type 2 diabetes melittus (T2DM) are two of the most common endocrine disorders, and the emerging condition of prediabetes necessitates additional research to better understand the complex interactions between thyroid hormones, metabolic regulation, and the progression from prediabetes to T2DM. This study sought to investigate changes in selected markers of thyroid function in patients with pre-diabetes. Upon obtaining ethics permission, blood samples were collected from patients in King Edward Hospital in Durban, South Africa. The samples were classified as non-diabetic, pre-diabetic, and type 2 diabetic using the ADA guidelines. The thyroid stimulating hormone (TSH), thyroxine (T4) triiodothyronine (T3), Thyroglobulin (TG), and thyroid peroxidase antibody (TPOAb) concentrations were determined in these samples. The results showed elevated TSH, decreased T3 and T4, decreased thyroglobulin (Tg), and elevated TPOAb in the prediabetic group which became considerably pronounced with the shift to T2DM. The alterations in these markers during prediabetes may indicate an early stage of thyroid dysfunction necessitating further investigation as these alterations become more pronounced during type 2 diabetes mellitus.

Correlation between diabetic peripheral neuropathy and thyroid hormone sensitivity in elderly patients with type 2 diabetes mellitus

BACKGROUND

Diabetic peripheral neuropathy (DPN) is a common complication of type 2 diabetes mellitus (T2DM), significantly affecting patients' quality of life and imposing a substantial economic burden. Recent studies have highlighted the role of thyroid hormones in diabetes complications, particularly in elderly patients with T2DM. However, the relationship between thyroid hormone sensitivity and DPN remains unclear.

AIM

To investigate the correlation between thyroid hormone sensitivity and DPN in elderly patients with T2DM.

METHODS

In a cohort of 256 elderly patients with T2DM, propensity score matching was used to balance age, sex, and diabetes duration. Clinical data were collected to calculate thyroid hormone sensitivity and analyze its correlation with DPN. A random forest model was used to evaluate the diagnostic value of free triiodothyronine/free thyroxine (FT3/FT4) for DPN.

RESULTS

Patients with DPN had a lower FT3/FT4 ratio [ (0.302 ± 0.053) vs (0.316 ± 0.049), P = 0.040]. Quartile stratification showed decreasing DPN prevalence with higher FT3/FT4 ratios. Spearman's correlation analysis showed that a lower FT3/FT4 ratio was associated with higher glycated hemoglobin, fasting blood glucose, reduced nerve conduction velocity, and electrical skin conductance. Logistic regression indicated a positive relationship between the median FT3/FT4 ratio and bilateral foot electrochemical skin conductance [odds ratio (OR): 1.019; 95%CI: 1.005-1.034; P = 0.007] and sural nerve sensory amplitude (OR: 1.310; 95%CI: 1.008-1.703; P = 0.043). Receiver operating characteristic analysis using a random forest model showed that incorporating FT3/FT4 improved predictive performance for DPN, with an area under the curve of 0.74, sensitivity of 0.79, specificity of 0.64, and accuracy of 0.77.

CONCLUSION

In elderly patients with T2DM with euthyroidism, a lower FT3/FT4 ratio is correlated with increased DPN incidence, affecting both large and small nerve fibers. FT3/FT4 is an effective predictor of DPN.

Relationship of thyroid parameters with chronic inflammation in patients with euthyroid type 2 diabetes

Aims

We evaluated the association of multiple thyroid parameters with the levels interleukin 6 (IL6) and interleukin 8 (IL8) in patients with euthyroid type 2 diabetes (T2D).

Methods

A total of 166 adults with euthyroid T2D were examined. Serum IL6, IL8, triiodothyronine (FT3), free thyroxin (FT4), thyroid-stimulating hormone (TSH), five thyroid sensitivity indexes (FT3/FT4, TSH index [TSHI], thyrotroph T4 resistance index [TT4RI], thyroid feedback quantile-based index by FT3 [TFQIFT3], and TFQIFT4), and biochemical parameters were determined.

Results

The median age was 64 years (IQR: 54.75,70) and the median duration of diabetes was 10 years (IQR: 3,18). Patients with high levels of IL6 (≥2.38 pg/mL) had lower levels of FT3 and TFQIFT3 (P<0.05). Patients with high levels of IL8 (≥18.1 pg/mL) had lower levels of TSH and higher levels of FT4 (P<0.05). IL6 was negatively correlated with FT3 (r=-0.359, P<0.001), TFQIFT3 (r=-0.273, P=0.009), and FT3/FT4 (r=-0.22, P=0.037). IL8 was negatively correlated with TSH (r=-0.256, P=0.01), TSHI (r=-0.226, P=0.033), and TT4RI (r=-0.244, P=0.021). Binary logistic regression analysis with multiple adjusted models showed that a high level of IL6 was negatively associated with FT3 (aOR: 0.529; 95%CI: 0.302, 0.926, P=0.026), and that a high level of IL8 was negatively associated with TSH (aOR: 0.343; 95%CI: 0.155, 0.759; P=0.008) and TT4RI (aOR: 0.398;95%CI: 0.191, 0.831; P=0.014).

Conclusion

Patients with euthyroid T2D who had lower levels of FT3 had significantly higher levels of IL6, and those with lower levels of TSH and TT4RI had significantly higher levels of IL8.

Impaired Sensitivity to Thyroid Hormones is Associated with Central Obesity in Euthyroid Type 2 Diabetes Mellitus Patients with Overweight and Obesity

Background

Thyroid hormone levels are associated with the distribution of body components in humans.

Objective

This study aimed to investigate the associations between thyroid hormone (TH) levels, central sensitivity to THs, and body composition in overweight and obese patients with euthyroid type 2 diabetes mellitus (T2DM).

Methods

This cross-sectional study included 1215 euthyroid T2DM patients (721 men and 494 women) aged 20-80 years. The thyroid hormone sensitivity indices included the thyroid feedback quartile-based index (TFQI), thyrotroph T3 resistance index (TT3RI), thyrotroph T4 resistance index (TT4RI), and thyroid-stimulating hormone index (TSHI). The appendicular fat ratio, trunk fat ratio, android fat ratio, gynoid fat ratio, and appendicular skeletal muscle mass (ASM) were measured via dual-energy X-ray absorptiometry.

Results

The data revealed a greater proportion of subjects with impaired central sensitivity to THs in the obese group. TFQIFT4 and TFQIFT3 levels were positively correlated with the upper limb fat ratio, lower limb fat ratio, gynoid fat ratio, and total fat ratio. TSHI was positively correlated with body mass index (BMI), upper limb fat ratio, lower limb fat ratio, trunk fat ratio, android fat ratio, gynoid fat ratio, total fat ratio, and appendicular skeletal muscle mass index (ASMI) in women. In men, TSHI was only positively correlated with upper limb fat ratio, lower limb fat ratio, and total fat ratio. Logistic regression analysis indicated that TT3RI and TFQIFT3 were independently and positively associated with central obesity and low muscle mass in overweight and obese men. No significant differences were found among the women.

Conclusion

THs central sensitivity is related to the body composition of euthyroid T2DM patients. Specifically, high levels of TT3RI and TFQIFT3 are associated with central obesity and low muscle mass in T2DM men with overweight and obesity.

Update on clinical and experimental management of diabetic cardiomyopathy: addressing current and future therapy

Diabetic cardiomyopathy (DCM) is a severe secondary complication of type 2 diabetes mellitus (T2DM) that is diagnosed as a heart disease occurring in the absence of any previous cardiovascular pathology in diabetic patients. Although it is still lacking an exact definition as it combines aspects of both pathologies - T2DM and heart failure, more evidence comes forward that declares DCM as one complex disease that should be treated separately. It is the ambiguous pathological phenotype, symptoms or biomarkers that makes DCM hard to diagnose and screen for its early onset. This re-view provides an updated look on the novel advances in DCM diagnosis and treatment in the experimental and clinical settings. Management of patients with DCM proposes a challenge by itself and we aim to help navigate and advice clinicians with early screening and pharmacotherapy of DCM.

Expressions of glycemic parameters, lipid profile, and thyroid hormone in patients with type 2 diabetes mellitus and their correlation

OBJECTIVE

This study aimed to investigate the expressions of glycemic parameters, lipid profile, and thyroid hormone in type 2 diabetes mellitus (T2DM) patients and their correlation.

METHODS

Eighty-four patients with T2DM in our hospital were included as the observation group. The T2DM patients were divided into mild group, moderate group, and severe group according to the fasting plasma glucose (FPG) level. Another 84 healthy subjects in the same period of health examination in our hospital were included as the control group. The levels of glycemic parameters, (HbA1c and FPG), lipid profile (TC, TG, LDL-C, and HDL-C) and thyroid hormone (FT3, TSH, and FT4) were measured by automatic biochemical analyzer. The correlation between glycemic parameters, lipid profile, and thyroid hormone was analyzed by Pearson correlation analysis.

RESULTS

The FPG, TC, TG, LDL-C, HbA1c, and TSH levels were significantly elevated, while the HDL-C and FT3 levels were significantly declined in the observation group versus to control group (p < .05). The levels of HbA1c, FPG, TC, LDL-C, and TSH were significantly increased, while the levels of HDL-C and FT3 were decreased in moderate and severe groups, when compared to mild group (p < .05). The levels of HbA1c, FPG, TC, LDL-C and TSH were higher, while the level of FT3 was lower in severe group than those in moderate group (p < .05). Pearson Correlation analysis showed that FT3 level in T2DM patients was positively correlated with FPG, HbAlc, TC, TG, and LDL-C levels (p < .05), but negatively correlated with HDL-C level (p < .05). TSH level was negatively correlated with FPG, HbAlc, TC, TG, and LDL-C levels (p < .05), while positively correlated with HDL-C level.

CONCLUSION

The thyroid hormone levels were of clinical significance in evaluating glycolipid metabolism and severity of T2DM. Clinical detection of glycolipid metabolism and thyroid hormone levels in T2DM patients is of great significance for diagnosis, evaluation, and targeted treatment of the disease.

Ethanolamine as a biomarker and biomarker-based therapy for diabetic retinopathy in glucose-well-controlled diabetic patients

Diabetic retinopathy (DR) is the leading cause of blindness among the working-age population. Although controlling blood glucose levels effectively reduces the incidence and development of DR to less than 50%, there are currently no diagnostic biomarkers or effective treatments for DR development in glucose-well-controlled diabetic patients (GW-DR). In this study, we established a prospective GW-DR cohort by strictly adhering to glycemic control guidelines and maintaining regular retinal examinations over a median 2-year follow-up period. The discovery cohort encompassed 71 individuals selected from a pool of 292 recruited diabetic patients at baseline, all of whom consistently maintained hemoglobin A1c (HbA1c) levels below 7% without experiencing hypoglycemia. Within this cohort of 71 individuals, 21 subsequently experienced new-onset GW-DR, resulting in an incidence rate of 29.6%. In the validation cohort, we also observed a significant GW-DR incidence rate of 17.9%. Employing targeted metabolomics, we investigated the metabolic characteristics of serum in GW-DR, revealing a significant association between lower levels of ethanolamine and GW-DR risk. This association was corroborated in the validation cohort, exhibiting superior diagnostic performance in distinguishing GW-DR from diabetes compared to the conventional risk factor HbA1c, with AUCs of 0.954 versus 0.506 and 0.906 versus 0.521 in the discovery and validation cohorts, respectively. Furthermore, in a streptozotocin (STZ)-induced diabetic rat model, ethanolamine attenuated diabetic retinal inflammation, accompanied by suppression of microglial diacylglycerol (DAG)-dependent protein kinase C (PKC) pathway activation. In conclusion, we propose that ethanolamine is a potential biomarker and represents a viable biomarker-based therapeutic option for GW-DR.

Estimated glucose disposal rate predicts the risk of diabetic peripheral neuropathy in type 2 diabetes: A 5-year follow-up study

BACKGROUND

Insulin resistance is associated with chronic complications of diabetes, including diabetic peripheral neuropathy (DPN). Estimated glucose disposal rate (eGDR), calculated by the common available clinical factors, was proved to be an excellent tool to measure insulin resistance in large patient population. Few studies have explored the association between eGDR and DPN longitudinally. Therefore, we performed the current study to analyze whether eGDR could predict the risk of DPN.

METHODS

In this prospective study, 366 type 2 diabetes (T2DM) subjects without DPN were enrolled from six communities in Shanghai in 2011-2014 and followed up until 2019-2020. Neuropathy was assessed by Michigan Neuropathy Screening Instrument (MSNI) at baseline and at the end of follow-up.

FINDINGS

After 5.91 years, 198 of 366 participants progressed to DPN according to MNSI examination scores. The incidence of DPN in the low baseline eGDR (eGDR < 9.15) group was significantly higher than in the high baseline eGDR (eGDR ≥ 9.15) group (62.37% vs. 45.56%, p = .0013). The incidence of DPN was significantly higher in patients with sustained lower eGDR level (63.69%) compared with those with sustained higher eGDR level (35.80%). Subjects with low baseline eGDR (eGDR < 9.15) had significantly higher risk of DPN at the end of follow-up (odds ratio = 1.75), even after adjusting for other known DPN risk factors.

CONCLUSIONS

The 5-year follow-up study highlights the importance of insulin resistance represented by eGDR in the development of DPN in T2DM. Diabetic patients with low eGDR are more prone to DPN and, therefore, require more intensive screening and more attention.

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.

Correlation Between Thyroid-Related Hormones and Diabetic Retinopathy in Type 2 Diabetes Mellitus Patients with Normal Thyroid Function: A Retrospective Study

Purpose

To investigate the correlation between thyroid-related hormones and diabetic retinopathy (DR) in euthyroid patients with type 2 diabetes mellitus (T2DM).

Patients and Methods

Patients with T2DM admitted to our hospital between January 2023 and June 2023 were retrospectively analyzed. The patients were divided into DR and non-diabetic retinopathy (NDR) groups according to whether DR occurred. Thyroid function-related hormones (TSH, FT3, and FT4), blood glucose indices (FBG and HbA1c), and blood lipid indices (HDL-C, LDL-C, TC, and TG) of the two groups were analyzed by univariate and multivariate logistic regression to explore the risk factors for DR. Pearson correlation analysis and multiple stepwise regression analysis were used to investigate the correlation of TSH or FT3 with FBG, HbA1c, and TG in DR patients.

Results

Of the 286 patients with T2DM included in this study, 101 (35.31%) developed DR and 185 (64.69%) did not. High TG, FBG, HbA1c, and TSH and low FT3 levels were independent risk factors for DR in T2DM patients. TSH positively correlated with TG, whereas FT3 negatively correlated with TG and HbA1c in T2DM patients with DR.

Conclusion

Higher TSH and lower FT3 in T2DM patients with normal thyroid function may affect glucose and lipid metabolism, thereby increasing the risk of DR.

Are there bidirectional associations between maternal thyroid function and glucose metabolism in singleton live births? A birth cohort study

(1) Aims: To examine the associations between maternal thyroid function and glucose metabolism during pregnancy. (2) Methods: This study was based on Ma' anshan Birth Cohort in China. Totally 2375 pregnant women were included in data analysis. Maternal thyroid-stimulating hormone (TSH), free thyroxine (FT4), thyroid peroxidase antibody (TPOAb) and fasting plasma glucose (FPG) levels during the first, second and third trimesters of pregnancy were measured retrospectively. Mplus 8.0 was used to construct a cross-lagged panel model to examine the potential bidirectional association between thyroid function and FPG levels throughout pregnancy. (3) Results: FT4 levels were positively correlated with FPG levels in the first trimester and negatively correlated with FPG levels in the second trimester. TSH levels were negatively associated with FPG levels in the second trimester, and in the first trimester, it could positively predict FPG levels in the second trimester. No significant association was found between TPOAb levels and FPG levels during pregnancy. (4) Conclusions: There was a non-bidirectional association between maternal thyroid function and glucose metabolism during pregnancy. FT4 and TSH levels influence FPG concentrations in the first and second trimesters of pregnancy.

B-cell-activating factor (BAFF) and platelet-activating factor (PAF) in pregnancies complicated by maternal obesity and diabetes: a preliminary study

OBJECTIVE

In pregnancies complicated by maternal obesity and diabetes, a disruption in inflammatory mediators occurs, resulting in endothelial microvascular dysfunction, oxidative stress, tissue damage, and maternal and feto-neonatal complications. To outline this proinflammatory status, an innovative approach is represented by the measurement of proinflammatory cytokines. Among these biomarkers, B-cell-activating factor (BAFF) and platelet-activating factor (PAF) play a key role in metabolic regulation, immune response to infections, tissue homeostasis, and "food-related inflammation." The aim of the present study is to investigate the blood expression of BAFF and PAF in a cohort of pregnant women affected by obesity and diabetes compared with a control group of healthy pregnant women.

METHODS

A prospective longitudinal cohort study has been conducted on pregnant women referred to Fondazione Policlinico Universitario Gemelli IRCCS in Rome. For each pregnant woman, a capillary sample was collected with a swab in three different consecutive evaluations carried out in the three trimesters of pregnancy.

RESULTS

A total of 77 pregnant women have been enrolled. No significant differences in BAFF and PAF levels were longitudinally observed between groups. Focusing on the exposed group, in the third trimester of pregnancy, both PAF and BAFF levels were lower than the basal time. Among the selected group of patients who developed Gestational Diabetes, only PAF values were longitudinally lower when compared to other groups. The multivariate analysis showed that BAFF levels were positively correlated with thyroid-stimulating hormone levels. No macrosomia, no shoulder dystocia, no major perineal lacerations at birth, and no intrauterine growth restriction were observed in the whole population.

CONCLUSIONS

This study supports the involvement of metabolic and proinflammatory biomarkers in the mechanisms related to pregnancy complications. Improving a good metabolic environment for obese and diabetic pregnant women could break the vicious cycle connecting inflammation, oxidative stress, and metabolic disorders.

Subclinical hypothyroidism increases insulin resistance in normoglycemic people

Objective

To investigate the effect of simple subclinical hypothyroidism (SCH) and type 2 diabetes mellitus (T2DM) combined with SCH on insulin resistance.

Design and methods

A total of 622 people with newly diagnosed T2DM were selected as the study subjects, and 621 normoglycemic people were selected as control subjects. According to the diagnostic criteria of thyroid diseases, the subjects were divided into a normal thyroid function group and a subclinical hypothyroidism group. Both groups received a physical examination, and blood samples were collected. The measurement indexes included FPG, FINS, OGTT2hPG, OGTT2hINS, HbA1c, TC, TG, HDL-C, LDL-C, TSH, FT3 and FT4. HOMA-IR, HOMA-β, and TFQI (thyroid feedback quantile index) were calculated.

Results

There was no significant difference in age or sex distribution between the T2DM group and the normoglycemic group (P>0.05). The prevalence of thyroid dysfunction in the T2DM group was significantly higher than that in the normoglycemic group (16.39% vs. 11.27%, P<0.05), and among the different types of thyroid dysfunction, the prevalence of SCH was the highest at 14.95% (P<0.05). There was no significant difference in BMI, waist-hip ratio, blood lipid profile, HOMA-β, and HOMA-IR values between the T2DM with subclinical hypothyroidism group (T2DM+SCH+ group) and the normal thyroid function group (T2DM+SCH- group) (P>0.05). The BMI, waist-hip ratio and HOMA-IR values of the normoglycemic group with subclinical hypothyroidism (T2DM-SCH+ group) were significantly higher than those of the normoglycemic group with normal thyroid function (T2DM-SCH- group) (P<0.05), and there were no significant differences between the T2DM+SCH- and T2DM+SCH+ groups (P>0.05). HOMA-β values were significantly higher in the T2DM-SCH+ group than in the T2DM-SCH-, T2DM+SCH- and T2DM+SCH+ groups (P<0.05). As the TFQI value increased, the body weight, waist-hip ratio, diastolic blood pressure, FPG, OGTT2hPG and HbA1c values gradually increased in the T2DM group and normoglycemic group (P<0.05). HDL-C, FINS, OGTT2hINS and HOMA-β values gradually decreased (P<0.05).

Conclusion

Subclinical hypothyroidism only increases insulin resistance in normoglycemic people. As the sensitivity of the central thyroid decreases, the risk of developing diabetes increases.

A Systematic Review and Meta-analysis examining the Risk of Adverse Pregnancy and Neonatal Outcomes in Women with Isolated Hypothyroxinemia in Pregnancy

BACKGROUND

The relationship between isolated hypothyroxinemia (IH) in pregnancy and adverse pregnancy outcomes is controversial, with no consensus on the need for treatment.

METHODS

We conducted a systematic review and meta-analysis examining adverse pregnancy and neonatal outcomes in women with isolated hypothyroxinemia (IH) in pregnancy. We searched PubMed, Embase, Web of Science and the Cochrane Central Register of Controlled Trials for publications from inception to December 2022. Randomized clinical trials and cohort studies were included. Random effects meta-analyses were used to estimate pooled relative risks (RRs) for each outcome.

RESULTS

We included 21 articles, of which 19 investigated the relationship between IH and maternal and neonatal outcomes and 4 investigated the efficacy of LT4 treatment. Compared with euthyroid pregnancies, IH pregnancies were associated with an increased risk of preterm birth (RR 1.35 [CI 1.16-1.56]; I2 = 9%), premature rupture of membranes (RR 1.41 [CI 1.08-1.84]; I2 = 0%), gestational diabetes (RR 1.34 [CI 1.07-1.67]; I2 = 76%), macrosomia (RR 1.62 [CI 1.31-2.02]; I2 = 42%), and fetal distress (RR 1.72 [CI 1.15-2.56]; I2 = 0%). However, no statistically significant differences were noted in adverse outcomes according to LT4 treatment status.

CONCLUSIONS

There is evidence suggesting that that IH in pregnancy may be associated with an increased risk of adverse pregnancy and neonatal outcomes. However, it is unclear whether LT4 may mitigate the risk of these adverse outcomes.

Obesity in Late-Life as a Protective Factor Against Dementia and Dementia-Related Mortality

OBJECTIVE

We estimated the conversion from cognitively normal to mild cognitive impairment (MCI) to probable dementia and death for underweight, normal, overweight, and obese older adults, where the timing of examinations is associated with the severity of dementia.

METHODS

We analyzed six waves of the National Health and Aging Trends Study (NHATS). Body mass (BMI) was computed from height and weight. Multi-state survival models (MSMs) examined misclassification probability, time-to-event ratios, and cognitive decline.

RESULTS

Participants (n = 6078) were 77 years old, 62% had overweight and/or obese BMI. After adjusting for the effects of cardiometabolic factors, age, sex, and race, obesity was protective against developing dementia (aHR=.44; 95%CI [.29-.67]) and dementia-related mortality (aHR=.63; 95%CI [.42-.95]).

DISCUSSION

We found a negative relationship between obesity and dementia and dementia-related mortality, a finding that has been underreported in the literature. The continuing obesity epidemic might complicate the diagnosis and treatment of dementia.

Advance in the Correlation between Diabetic Nephropathy and Abnormal Serum Thyroid Hormone Levels in Patients

This study was developed to explore the correlation between diabetic nephropathy (DN) and abnormal serum thyroid hormone (TH) levels in patients, which can provide a reference for disease prevention and control in patients with DN. DN is the most serious complication of diabetes. The mortality rate of diabetic patients with DN is approximately 30 times higher than that of diabetic patients without DN. DN leads to high blood sugar, which causes vascular dysfunction in patients, causes cardiovascular disease, aggravates the disease and disease complexity, and thus increases the mortality of patients. DN patients often have oxidative stress and even fibrosis in severe cases. TH has a potential renal protective effect and can also regulate glucose metabolism and improve abnormal glucose tolerance and insulin resistance. Abnormal serum TH levels increase the risk of DN. Normal thyroid function plays an important role in regulating the physiological functions of the human body. Hormonal disorders promote the development of diabetes mellitus (DM) into DN. The pathogenesis, clinical manifestations, detection, and treatment methods of DN were reviewed in this study. The research progress of the influence of TH on DN was analyzed. This study is conducive to clinical research on DN and provides a reference.

The correlation between triiodothyronine and the severity of liver fibrosis

BACKGROUND

The severity of liver fibrosis is an important predictor of death in patients with non-alcoholic fatty liver disease (NAFLD) and type 2 diabetes mellitus (T2DM). However, there is still no definite conclusion on the relationship between triiodothyronine (T3) and the severity of liver fibrosis. Thus, the aim of this study was to analyze the correlation between T3 level and the severity of liver fibrosis.

METHODS

We performed a cross-sectional study of 2072 T2DM patients with normal thyroid function from January 2017 to January 2020. NAFLD fibrosis score (NFS), Fibrosis index based on the 4 factors (FIB-4) and BARD score (BARD) were used to assess the severity of fibrosis in T2DM patients, and linear regression analyses were used to determine the factors independently associated with liver fibrosis. Further experiments were performed to assess the impact of low T3 on fibrosis progression in mice model and explore possible mechanisms.

RESULTS

Free triiodothyronine (fT3) levels had significantly inverse correlations with NFS and FIB-4, and BARD in T2DM patients (P < 0.05). In multiple linear regression analyses, decreased fT3 level was an independent risk factor for the severity of liver fibrosis of T2DM patients (P < 0.01). Findings from in-vivo experiment using mice model proved that hypothyroidism mice had more severe of liver fibrosis than those mice with normal thyroid function. We also found that T3 could inhibit the profibrotic TREM2⁺CD9⁺ macrophage, which had been identified an important player in the progression of liver fibrosis.

CONCLUSION

The findings from this study proved an inverse correlation between T3 level and the severity of liver fibrosis, and lower fT3 level within the normal range was an independent risk factor for severe liver fibrosis.

Low FT3/FT4 Ratio Is Linked to Poor Prognosis of Acute Myocardial Infarction in Euthyroid Patients with Type 2 Diabetes Mellitus

This is an observational, retrospective, single-center study aimed to determine whether the free triiodothyronine (FT3) to free thyroxine (FT4) ratio was related to acute myocardial infarction (AMI) prognosis in individuals with type 2 diabetes mellitus (T2DM). A total of 294 euthyroid T2DM patients with new-onset AMI were enrolled. FT3/FT4 ratio tertiles were used to categorize patients into Group 1 (FT3/FT4 ≥ 4.3), Group 2 (3.5 ≤ FT3/FT4 < 4.3), and Group 3 (FT3/FT4 < 3.5). Major adverse cardiac events (MACE), including nonfatal myocardial infarction, target vessel revascularization (TVR), and cardiac mortality, served as the primary endpoint. Group 3 demonstrated a considerably higher incidence of MACE than the other two groups over the average follow-up duration of 21 ± 6.5 months (all p < 0.001). Multivariable Cox regression analysis showed that a low FT3/FT4 ratio was an independent risk factor for MACE after AMI (Group 1 as a reference; Group 2: hazard ratio [HR] 1.275, 95% confidence interval [CI]: 0.563−2.889, p = 0.561; Group 3: HR 2.456, 95% CI: 1.105−5.459, p = 0.027). Moreover, the area under the receiver-operating characteristic curve (AUC) indicates a good predictive value of FT3/FT4 ratio for MACE (AUC = 0.70). Therefore, in T2DM patients with AMI, a low FT3/FT4 ratio was strongly linked to poor prognosis.

Analysis of risk factors for the development of type 2 diabetes mellitus complicated with Hashimoto's thyroiditis

AIMS

The purpose of this study is to elucidate the correlation between thyroid hormone, glycosylated hemoglobin (HbA1c), vitamin D and type 2 diabetes mellitus (T2DM) with Hashimoto's thyroiditis (HT), and to seek the independent predictors affecting disease development.

METHODS

The study included 44 T2DM with HT, 94 T2DM, and 112 healthy subjects. We investigated some laboratory factors like thyroid hormone and compared the levels. Independent predictors determination by logistic univariate regression analysis were analyzed. The diagnostic value of thyroid-stimulating hormone (TSH) and threshold concentration were determined by ROC curve.

RESULTS

In T2DM with HT group, levels of PTH, HbA1c were lower and levels of TSH were significantly higher, when compared with T2DM group. But there was no significant difference in vitamin D between these two groups. In both logistic univariate regression analysis and multiple logistic regression analysis, TSH, HbA1c were independent predictors for T2DM with HT. Based on the ROC curve, the best cut-off value of the TSH was 4 mIU/L (sensitivity 72.7%, specificity 94.6%, AUC = 0.832) for predicting T2DM with HT in T2DM patients.

CONCLUSIONS

TSH has increased risk for T2DM evolving into T2DM complicated with HT, so it is important to monitor the concentrations of TSH in patients with T2DM. Although vitamin D was not the independent predictor in T2DM with HT development, effect of vitamin D deficiency on the progress of diabetes and its complications should be taken into consideration.

Thyroid-Stimulating Hormone and Thyroid Hormones and Incidence of Diabetes: Prospective Results of the Brazilian Longitudinal Study of Adult Health (ELSA-BRASIL)

Background: There are conflicting data regarding the association of thyroid function with incident diabetes. We prospectively investigated thyrotropin (TSH), free thyroxine (fT4), free triiodothyronine (fT3), and its conversion ratio (fT3:fT4) with the risk of developing diabetes in euthyroid subjects and those with subclinical thyroid dysfunction. Our hypothesis is that this relationship is a U-shaped curve since both subclinical thyroid diseases may be associated with diabetes. Methods: ELSA-Brasil is a highly admixed cohort study of 35-74 years old at baseline (2008-2010). Levels of TSH, fT4, fT3, and fT3:fT4 ratio were evaluated at baseline and incident diabetes was estimated over an 8.2-year follow-up (2017-2019). Diabetes was identified based on medical diagnosis, prescriptions, and laboratory tests. The risk of diabetes was evaluated according to quintiles of TSH, fT4, fT3, and fT3:fT4 ratio using Poisson regression with robust variance presented as relative risk (RR) with confidence interval [CI] of 95% after multivariable adjustment for sociodemographic and cardiovascular risk factors (reference third quintile), and as continuous variables. Results: We included 7948 participants (mean age, 50.2 [standard deviation 8.6] years; 54.4% female): 7177 euthyroid, 726 with subclinical hypothyroidism, and 45 with subclinical hyperthyroidism. Incidence of diabetes was 14.8%. No association was found for TSH, fT4, fT3, and fT3:fT4 ratio quintiles with incident diabetes. Using continuous variables, the increase of 1-unit (1-U) of fT4 decreased the risk of diabetes (RR 0.94 [CI 0.91-0.99]), while the increase of 1-U of the fT3:fT4 ratio increased the diabetes risk (RR 1.37 [CI 1.15-1.63]). The increase of 1-U of fT3 was associated with an increased risk of diabetes, but without significance after multivariable adjustment. In body mass index-stratified analysis, people with overweight or obesity presented a modest significantly higher risk of diabetes in the lowest quintile of fT4 (RR 1.04 [CI 1.01-1.07]) and an inverse association with incident diabetes in the first quintile of fT3:fT4 ratio (RR, 0.95 [CI 0.93-0.98]). The analyses using continuous variables presented similar findings. Conclusion: These findings suggest that fT4 and fT3 levels and the conversion rate might be additional risk factors associated with incident diabetes, especially in the presence of overweight or obesity. However, they need to be confirmed in future studies. (ClinicalTrials.gov Identifier: NCT02320461).

Subsequent perinatal outcomes of pregnancy with two consecutive pregnancies with gestational diabetes mellitus: A population-based cohort study

BACKGROUND

Gestational diabetes mellitus (GDM) is glucose intolerance diagnosed during pregnancy. We aimed to explore the different outcomes of women with two consecutive pregnancies with GDM.

METHODS

This study included 861 women with recurrent GDM who had two consecutive singleton deliveries at Fujian Maternity and Child Health Hospital between May 2012 and September 2020. Data on pregnancy complications and neonatal and delivery outcomes were collected and analyzed.

RESULTS

Among those women with recurrent GDM, there was no difference in pregnancy complications in index pregnancy vs subsequent pregnancy. Our data revealed there was a significantly higher incidence of thyroid disease in the subsequent pregnancies than in the index pregnancy. (6% vs 10%, p = .003)In subsequent pregnancies, the birth weight was greater than that of the index pregnancy (3296.63 ± 16.85 vs 3348.99 ± 16.05, p = .025); and the incidence of large for gestational age (LGA) was higher than that of the index pregnancy (16.3% vs 20.6%, p = .021). More cesarean sections occurred in the subsequent pregnancy. (32.9% vs 6.6%, p = .039). Postpartum hemorrhage, premature birth, and placental abruption were not significantly different between the two pregnancies.

CONCLUSIONS

The results suggest the effect of GDM on thyroid dysfunction may be persistent. Recurrent gestational diabetes results in a higher rate of cesarean delivery, incidence of LGA, and neonatal admission to the neonatal intensive care unit (NICU) in subsequent pregnancies. We need to pay attention to the postpartum thyroid function of pregnant women with GDM. Further studies are still needed on recurrent GDM to reduce this occurrence of admission to NICU.

Serum spexin differed in newly diagnosed type 2 diabetes patients according to body mass index and increased with the improvement of metabolic status

OBJECTIVE

The aim of this study was to explore serum spexin levels in newly diagnosed type 2 diabetes mellitus (T2DM) patients with different body mass indexes (BMIs) and to investigate the changes of spexin after improvement of metabolic indicators.

METHODS

A total of 323 newly diagnosed T2DM patients from national Metabolic Management Center (MMC) in Shanghai General Hospital were recruited. T2DM patients were categorized into three groups: diabetes with obesity group (DM-OB group, BMI≥28 kg/m², n=89), diabetes with overweight group (DM-OV group, 24≤BMI<28 kg/m², n=161), and diabetes with normal weight group (DM-NW group, 18≤BMI<24 kg/m², n=73). In addition, 41 volunteers with normal glucose tolerance (NGT) were used as controls. Spexin and metabolic parameters were compared at baseline, and changes after MMC follow-up in 100 DM patients were investigated.

RESULTS

In the DM-OB group, the level of spexin was significantly lower than that in the DM-OV group and the DM-NW group (P < 0.01). Spexin was significantly negatively related to body mass index (BMI, β=-0.214, P<0.001), waist circumference (β=-0.249, P<0.001), visceral fat area (VFA, β=-0.214, P<0.001), and subcutaneous fat area (SFA, β=-0.265, P<0.001) after adjustment for age and sex. Among all the metabolic indicators, the decline in BMI in the DM-OB group was the most obvious among those in the three groups (-3.7 ± 0.8 kg/m² vs. -0.9 ± 0.3 kg/m² vs. 0.7 ± 0.6 kg/m², P<0.01) after one year of MMC standardized management. The serum spexin level in the DM-OB group increased the most (1.00 ± 0.10 ng/mL vs. 0.49 ± 0.06 ng/mL in DM-OV group and 0.58 ± 0.09 ng/mL in DM-NW group, P < 0.001).

CONCLUSIONS

Serum spexin differed in newly diagnosed T2DM patients according to BMI and was lowest in the DM-OB group. With the improvement of metabolic indicators, especially the decline in BMI, serum spexin increased significantly after MMC management.

Potential Risk Factors for Isolated Hypothyroxinemia in Women of Childbearing Age-Results from Retrospective Analysis

Isolated hypothyroxinemia (IH) unfavorably affects reproduction. This study aimed to evaluate retrospectively if any routinely measured clinical/laboratory parameters are associated with IH among women of childbearing age hospitalized in the endocrine department. A group of 466 female non-pregnant inpatients (age range 13-57 years) was considered. IH (decreased free thyroxine (FT4) with normal TSH) was found in 8/466 patients (1.72%). Vitamin D deficiency (<30 ng/mL) was found in all patients with IH, whereas severe Vitamin D deficiency (<20 ng/mL) was found in 5/6. Vitamin D concentration was lower in IH females. FT4 concentration was lower in patients with severe vitamin D deficiency and correlated positively with vitamin D concentration. Insulin resistance index (IRI) was increased (>1.25) in 5/6 patients with IH. IRI was higher in IH patients and it was the only independent linear factor for IH in the univariate regression. FT4 concentration was lower in patients with increased IRI and correlated negatively with IRI. FT4 concentration correlated negatively with body mass index (BMI) and LDL cholesterol or triglycerides, and positively with HDL cholesterol or HDLC/cholesterol ratio. Vitamin D deficiency, insulin resistance and increased BMI (as potential causative factors), and abnormal lipid profile (as a possible consequence), are associated with IH in women of childbearing age. Eliminating risk factors for hypothyroxinemia may improve reproductive health.

Association of thyroid disorders with gestational diabetes mellitus: a meta-analysis

PURPOSE

The current meta-analysis aimed to evaluate the association of thyroid dysfunction and autoimmunity with gestational diabetes mellitus (GDM).

METHODS

A comprehensive search from PubMed, Embase, MEDLINE, and Cochrane databases until November 2020 was conducted. Fixed-effect model was used to combine the results when I² was <50%. Random-effect model was used to summarize the results when I² was >50%.

RESULTS

A total of 44 studies were included in the meta-analysis. Low FT4 levels were closely related with GDM in the first and second trimesters of gestation. Hypothyroxinemia (OR: 1.45; 95% CI: 1.25, 1.68; P < 0.00001), overt (OR: 1.80; 95% CI: 1.73, 1.86; P < 0.00001), and subclinical (OR: 1.54; 95% CI: 1.03, 2.30; P = 0.03) hypothyroidism, overt hyperthyroidism (OR: 1.49; 95% CI: 1.09, 2.04; P = 0.01), and positive thyroid antibodies (OR: 1.49; 95% CI: 1.07, 2.07; P < 0.00001) were observed significantly associated with the risk of GDM. Pregnant women with subclinical hyperthyroidism were less likely to develop GDM (OR: 0.62; 95% CI: 0.39, 0.97; P = 0.04).

CONCLUSIONS

Thyroid dysfunction and positive thyroid antibodies were associated with the risk of GDM. Our findings suggest that pregnant women with these thyroid diseases may be offered screening for GDM comprehensively.

Sensitivity to Thyroid Hormones and Risk of Prediabetes: A Cross-Sectional Study

CONTEXT

Thyroid hormone influences glucose homeostasis through central and peripheral regulations. To date, the link between sensitivity to thyroid hormones and prediabetes remains unknown. We aimed to investigate the association between thyroid hormones sensitivity and risk of prediabetes in both general and euthyroid populations.

METHODS

Participants with serum free triiodothyronine (FT3), free thyroxine (FT4), and thyrotropin (TSH) measurements from the health checkup programs of the First Hospital of China Medical University were collected. We measured the parameters representing central and peripheral sensitivities to thyroid hormones (central sensitivity, assessed by calculating Thyroid Feedback Quantile-based Index (TFQI), TSH Index (TSHI), and Thyrotroph Thyroxine Resistance Index (TT4RI); peripheral sensitivity, evaluated by FT3/FT4 ratio). Associations between thyroid hormones sensitivities and risk of prediabetes were assessed with logistic regression.

RESULTS

A total of 4378 participants (mean age ± SD, 49 ± 11 years) were included, with 1457 (33%) subjects had prediabetes. The risk of prediabetes was negatively associated with levels of TSHI (odds ratio [OR] 0.91; 95% confidence interval [CI], 0.85-0.97), TT4RI (OR 0.91; 95% CI, 0.84-0.99) and Parametric TFQI (PTFQI) (OR 0.89; 95% CI, 0.83-0.95) among all subjects. The association remained significant in euthyroid subjects and euthyroid subjects with negative thyroid autoimmunity. Higher FT3/FT4 ratio was associated with a mild increased risk of prediabetes (95% CI 1.09; 1.02-1.16). Compared with subjects in the lowest quartile of PTFQI, those in the highest quartile had lower risk of prediabetes (0.70; 95% CI, 0.58-0.84).

CONCLUSIONS

Decreased central sensitivity to thyroid hormones is associated with lower risk of prediabetes. This demonstrates the complex interaction between thyroid system and glucose metabolism. Future studies are warranted to confirm our findings and underlying mechanisms.