Insulin sensitivity modifies the relationship between thyroid function and lipid profile in euthyroid type 1 diabetic patients

Association between sensitivity to thyroid hormones and non-high-density lipoprotein cholesterol levels in patients with type 2 diabetes mellitus

BACKGROUND

Dyslipidemia and type 2 diabetes mellitus (T2DM) are chronic conditions with substantial public health implications. Effective management of lipid metabolism in patients with T2DM is critical. However, there has been insufficient attention given to the relationship between thyroid hormone sensitivity and dyslipidemia in the T2DM population, particularly concerning non-high-density lipoprotein cholesterol (non-HDL-C).

AIM

To clarify the association between thyroid hormone sensitivity and dyslipidemia in patients with T2DM.

METHODS

In this cross-sectional study, thyroid hormone sensitivity indices, the thyroid feedback quantile-based index (TFQI), the thyroid-stimulating hormone index (TSHI), the thyrotrophic T4 resistance index (TT4RI), and the free triiodothyronine (FT3)/free thyroxine (FT4) ratio were calculated. Logistic regression analysis was performed to determine the associations between those composite indices and non-HDL-C levels. Random forest variable importance and Shapley Additive Explanations (SHAP) summary plots were used to identify the strength and direction of the association between hyper-non-HDL-C and its major predictor.

RESULTS

Among the 994 participants, 389 (39.13%) had high non-HDL-C levels. Logistic regression analysis revealed that the risk of hyper-non-HDL-C was positively correlated with the TFQI (OR: 1.584; 95%CI: 1.088-2.304; P = 0.016), TSHI (OR: 1.238; 95%CI: 1.034-1.482; P = 0.02), and TT4RI (OR: 1.075; 95%CI: 1.006-1.149; P = 0.032) but was not significantly correlated with the FT3/FT4 ratio. The relationships between composite indices of the thyroid system and non-HDL-C levels differed according to sex. An increased risk of hyper-non-HDL-C was associated with elevated TSHI levels in men (OR: 1.331; 95%CI: 1.003-1.766; P = 0.048) but elevated TFQI levels in women (OR: 2.337; 95%CI: 1.4-3.901; P = 0.001). Among the analyzed variables, the average SHAP values were highest for TSHI, followed by TT4RI.

CONCLUSION

Impaired sensitivity to thyroid hormones was associated with high non-HDL-C levels in patients with T2DM.

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.

Reduced Sensitivity to Thyroid Hormones Is Associated With High Remnant Cholesterol Levels in Chinese Euthyroid Adults

CONTEXT

It remains unclear whether the thyroid system could regulate the atherogenic remnant cholesterol (RC) levels in euthyroid status.

OBJECTIVE

We aimed to investigate the relationship between sensitivity to thyroid hormones and RC levels in Chinese euthyroid population.

METHODS

This study included 18 766 euthyroid adults. High RC levels were defined as the upper quartile of RC levels. The thyroid hormone sensitivity indices, including thyroid feedback quantile-based index (TFQI), thyroid-stimulating hormone index (TSHI), thyrotrophic thyroxine resistance index (TT4RI), and free triiodothyronine to free thyroxine (FT3/FT4) ratio were calculated. Linear and binary logistic regression analysis were applied to determine the associations between those composite indices with RC levels by genders.

RESULTS

Both females and males with high RC levels exhibited co-existing higher TSH and FT4 levels. Linear regression analysis revealed that TFQI, TSHI, and TT4RI were positively, while FT3/FT4 ratio levels were negatively associated with serum RC levels. The odds ratios (ORs) (95% CI) for high RC levels were increased with rising TFQI quartiles (Q) [females: Q3 1.41 (1.22-1.63), Q4 1.61 (1.39-1.86); males: Q3 1.25 (1.09-1.45), Q4 1.38 (1.19-1.59), all P for trend < 0.001] after full adjustment, with Q1 as the reference. TSHI and TT4RI yielded similar results. By contrast, the ORs (95% CI) for high RC levels were decreased with increasing FT3/FT4 ratio quartiles in both genders (P for trend < 0.001).

CONCLUSION

In euthyroid adults, reduced sensitivity to thyroid hormones was associated with high RC levels. Our results suggested an additive cardiometabolic risk of euthyroid population with thyroid hormones insensitivity.

The thyroid hormone levels and glucose and lipid metabolism in children with type 1 diabetes: a correlation analysis

BACKGROUND

Type 1 diabetes mellitus (T1DM) is common in clinical setting, the relationship between thyroid hormone levels and glucose and lipid metabolism in patients with T1DM remains unclear. We attempted to analyze the correlation of thyroid hormone levels and blood glucose and lipid metabolism in children with normal thyroid function.

METHODS

Children with T1DM were selected, and 85 healthy children who underwent physical examinations in our hospital as control group. The characteristics and laboratory testing results were compared, the correlation of thyroid hormone levels with blood glucose and blood lipids was analyzed by Pearson correlation analysis.

RESULTS

A total of 167 participants were included. the low-density lipoprotein-cholesterol (LDL-C), triglyceride (TG), fasting blood glucose (FBG), and glycated hemoglobin (HbAlc) in T1DM patients were higher than those in healthy controls, while the high-density lipoprotein-cholesterol (HDL-C), thyroid stimulating hormone (TSH) and free triiodothyronine (FT3) in T1DM patients were lower than that of healthy children (all P<0.05). TSH was positively correlated with LDL-C (r=0.169, P=0.032), TC (r=0.182, P=0.017) and TG (r=0.197, P=0.008), negatively correlated with FBG (r=-0.196, P=0.023) and HbAlc (r=-0.328, P=0.002). FT3 was negatively correlated with TG (r=-0.182, P=0.011), FBG (r=-0.184, P=0.009) and HbAlc (r=-0.223, P=0.005). TG in the high TSH group and the middle TSH group is higher than that of low TSH group. However, FBG and HbAlc were lower than those in the low TSH group (all P<0.05). Compared with the low FT3 group, the TG, FBG and HbAlc decreased in the high and middle FT3 group (all P<0.05).

CONCLUSIONS

The serum TSH are closely associated with FT3 and glycolipid metabolism in children with T1DM, which may be the useful indicators to assess the severity of T1DM in clinical settings to provide insights into the management of T1DM.

Association between thyroid hormone parameters and dyslipidemia among type 2 diabetes mellitus patients: Comparative cross-sectional study

BACKGROUND

The relationship between thyroid function and lipid profile has been documented in T2DM and healthy subjects. The aim of the current study was to assess the association between thyroid hormone parameters and dyslipidemia in T2DM and non-diabetic study participants.

METHOD AND MATERIALS

In this comparative cross-sectional study, 214 type 2 diabetic and 214 non-diabetic study participants were enrolled. Clinical and anthropometric data were collected from all study participants. After overnight fasting, 10ml of whole blood samples were drawn for the measurement of serum TSH, free thyroxine (fT4), free triiodothyronine (fT3), serum reactive C-protein levels, as well as for lipid profile test and glucose.

RESULT

The burden of hypothyroidism and subclinical hypothyroidism among T2DM study participants were 73 (17.05%) and 13 (3.04%) respectively. Comparatively, T2DM study participants had significantly higher serum lipid level than non-diabetics. Stratified by TSH, hypothyroid T2DM study participants had increased lipid level than euthyroid subjects. T2DM serum TSH have shown a positive significant correlation with all lipid profile parameters except HDL-C. In the final model (multivariate linear regression), diabetics serum TSH significantly and positively associated with TG and BMI. Diabetic serum fT3 and fT4 negatively associated with body mass index. In addition, diabetics serum fT3 negatively and serum fT4 positively associated with TC and HDL-C respectively.

CONCLUSION

T2DM study subjects had significantly higher lipid level than nondiabetic and We identified that TSH was positively associated with serum TG and BMI among T2DM study participants.

Relation of thyroid hormone abnormalities with subclinical inflammatory activity in patients with type 1 and type 2 diabetes mellitus

Thyroid hormone (TH) abnormalities are common in patients with diabetes mellitus (DM). These thyroid hormone abnormalities have been associated with inflammatory activity in several conditions but this link remains unclear in DM. We assessed the influence of subclinical inflammation in TH metabolism in euthyroid diabetic patients. Cross-sectional study involving 258 subjects divided in 4 groups: 70 patients with T2DM and 55 patients with T1DM and two control groups of 70 and 63 non-diabetic individuals, respectively. Groups were paired by age, sex, and body mass index (BMI). We evaluated the association between clinical and hormonal variables [thyrotropin, reverse T3 (rT3), total and free thyroxine (T4), and triiodothyronine (T3)] with the inflammation markers C-reactive protein (hs-CRP), serum amyloid A (SAA), and interleukin-6 (IL-6). Serum T3 and free T3 were lower in patients with diabetes (all P < 0.001) compared to the control groups. Interleukin-6 showed positive correlations with rT3 in both groups (P < 0.05). IL-6 was independently associated to FT3/rT3 (B = -0.193; 95% CI -0.31; -0.076; P = 0.002) and FT4/rT3 (B = -0.107; 95% CI -0.207; -0.006; P = 0.039) in the T1DM group. In the T2DM group, SAA (B = 0.18; 95% CI 0.089; 0.271; P < 0.001) and hs-CRP (B = -0.069; 95% CI -0.132; -0.007; P = 0.03) predicted FT3 levels. SAA (B = -0.16; 95% CI -0.26; -0.061; P = 0.002) and IL6 (B = 0.123; 95% CI 0.005; 0.241; P = 0.041) were related to FT4/FT3. In DM, differences in TH levels compared to non-diabetic individuals were related to increased subclinical inflammatory activity and BMI. Altered deiodinase activity was probably involved. These findings were independent of sex, age, BMI, and HbA1c levels.

Serum cholesterol and triglyceride concentrations in diabetic patients with subclinical hypothyroidism

OBJECTIVE

To assess whether subclinical hypothyroidism is associated to elevations in serum cholesterol and triglyceride levels in patients with type 2 diabetes.

PATIENTS AND METHODS

From a total population of 1,112 patients with type 2 diabetes screened for thyroid dysfunction (thyrotropin measurement), a group of 325 patients with normal thyroid function and another group of 29 patients with subclinical hypothyroidism were selected. No patient had known dyslipidemia or was taking lipid lowering medication.

RESULTS

Patients with subclinical hypothyroidism had serum levels of total cholesterol (4.88 ± 0.74 mmol/L), HDL cholesterol (1.37 ± 0.34 mmol/L), LDL cholesterol (2.94 ± 0.58 mmol/L), and triglycerides (1.05 [0.88-1.41] mmol/L) that did not significantly differ from those found in euthyroid patients (4.79 ± 0.83, 1.33 ± 0.36, 2.87 ± 0.76, and 1.11 [0.81-1.43] mmol/L, respectively). Multiple regression analysis showed no association between TSH and serum lipid levels.

CONCLUSION

These results suggest that, in our population, there are no significant differences in serum cholesterol and triglyceride levels between diabetic patients with normal and reduced thyroid function.