Interrelationships between the pancreas and the thyroid

Integration of clinical demographics and routine laboratory analysis parameters for early prediction of gestational diabetes mellitus in the Chinese population

Gestational diabetes mellitus (GDM) is one of the most common complications in pregnancy, impairing both maternal and fetal health in short and long term. As early interventions are considered desirable to prevent GDM, this study aims to develop a simple-to-use nomogram based on multiple common risk factors from electronic medical health records (EMHRs). A total of 924 pregnant women whose EMHRs were available at Peking University International Hospital from January 2022 to October 2022 were included. Clinical demographics and routine laboratory analysis parameters at 8-12 weeks of gestation were collected. A novel nomogram was established based on the outcomes of multivariate logistic regression. The nomogram demonstrated powerful discrimination (the area under the receiver operating characteristic curve = 0.7542), acceptable agreement (Hosmer-Lemeshow test, P = 0.3214) and favorable clinical utility. The C-statistics of 10-Fold cross validation, Leave one out cross validation and Bootstrap were 0.7411, 0.7357 and 0.7318, respectively, indicating the stability of the nomogram. A novel nomogram based on easily-accessible parameters was developed to predict GDM in early pregnancy, which may provide a paradigm for repurposing clinical data and benefit the clinical management of GDM. There is a need for prospective multi-center studies to validate the nomogram before employing the nomogram in real-world clinical practice.

FT3/FT4 mediated the effect of pre-pregnancy body mass index or maternal weight gain during early pregnancy on gestational diabetes mellitus

OBJECTIVE

Maternal overweight or obesity during early pregnancy could increase the subsequent risk of gestational diabetes mellitus (GDM). However, whether these associations were mediated by thyroid hormones and their effect sizes were still unknown. This study aimed to identify the mediating effects of thyroid parameters between pre-pregnancy body mass index (BMI)/maternal weight gain during early pregnancy with subsequent risk of GDM.

METHODS

This prospective mother-infant cohort study was conducted from 2018 to 2019. A total of 2,772 singleton pregnant women were included for analysis. Questionnaire survey, anthropometric measures, and thyroid function testing were conducted in early pregnancy. Deiodinase activity was evaluated using free-triiodothyronine-to-free-thyroxine ratio (FT3/FT4). A standard 75 g oral glucose tolerance test was performed during 24-28 weeks of gestation to diagnose GDM. Mediation analysis was performed on PROCESS 3.5 to examine the mediating effects of thyroid parameters between pre-pregnancy BMI/maternal weight gain during early pregnancy and the subsequent GDM risk.

RESULTS

FT3/FT4 ratio was a significant mediator between pre-pregnancy BMI or maternal weight gain and GDM, accounting for 16.5% and 18.6% of total effects, respectively. FT3 also mediated the association of pre-pregnancy BMI with GDM, accounting for 3.3% of total effects. Thyroid-stimulating hormone suppressed the effects of pre-pregnancy BMI and maternal weight gain on GDM risk, and the proportions of total effects were 2.4% and 6.4%, respectively.

CONCLUSIONS

Deiodinase activity, as indicated by FT3/FT4 ratio, was the strongest mediator among thyroid parameters between pre-pregnancy BMI/maternal early weight gain and GDM.

Perinatal effects of maternal FT3/FT4 ratio on gestational transient thyrotoxicosis

OBJECTIVE

The effects of maternal thyroid hormone levels on the course of pregnancy and birth weight have attracted interest. The aim of the present study was to consider FT3 and FT3/FT4 ratio in the evaluation of the effects of maternal thyroid functions in gestational transient thyrotoxicosis (GTT).

METHODS

This case-control study included 45 patients with GTT and 45 healthy pregnant women. Maternal history before pregnancy, thyroid function tests, thyroid autoantibodies, and thyroid ultrasonography results in 6th to 10th weeks of pregnancy were used in the differential diagnosis of GTT. In both groups, the effects of FT3, FT4 and FT3/FT4 ratios on gestational age and birth weight were evaluated.

RESULTS

There was no significant difference in the gestational age between the GTT and control groups (39,3±1,0 weeks and 39,2±1,2 weeks, respectively). Birth weights were similar in both groups (3205,2±4899 g and 3196,6±309,3 g, respectively). When maternal weight was adjusted, a positive correlation was observed between maternal FT3/FT4 ratio and birth weight (r=0,317, p=0,017). Additionally there was a positive correlation between the gestational age and the birth weight in the control group (ρ=0,726, p=0,001).

CONCLUSION

GTT had no significant effect on the gestational age and the birth weight. On the other hand an increase in the maternal FT3/FT4 ratio had a positive effect on the birth weight in the patient with GTT. Maternal characteristics (age, weight, BMI) and FT3/FT4 ratio should be taken into consideration in future impact assessment studies on this issue.

No Association between 25-Hydroxyvitamin D and Insulin Resistance or Thyroid Hormone Concentrations in a Romanian Observational Study

Background and objectives: Vitamin D is involved in insulin resistance through genomic and non-genomic mechanisms. Several observational and randomized studies have discrepant results; some of them showed an improved insulin resistance (IR), and others a neutral effect after vitamin D deficiency is corrected. Materials and Methods: We designed a retrospective observational study that included all women who presented for 33 months in an outpatient clinic in Bucharest, Romania. Results: We analyzed 353 patients with a mean age of 58.5 ± 13.7 years, a mean body mass index (BMI) of 27.36 ± 4.87 kg/m^-2, and a mean level of 25-hydroxyvitamin D (25OHD) of 39.53 ± 15.73 ng/mL. There were no differences in the calculated Homeostatic Model Assessment of Insulin Resistance variants 1 and 2 (HOMA-IR) and the Quantitative Insulin Sensitivity Check Index (QUICKI) between women with vitamin D deficit versus normal values. In multivariate analysis, there was no significant relation between 25OHD and the response variables considered by us. Conclusions: We observed a small positive correlation between a higher level of 25OHD and increased glycosylated hemolobin (HbA1c) or IR indices without clinical significance. Other modifiable or non-modifiable factors override 25OHD influence on IR in adult women with a normal serum level and may contribute to the remainder of the variability observed.

Maternal BMI, Peripheral Deiodinase Activity, and Plasma Glucose: Relationships Between White Women in the HAPO Study

OBJECTIVES

Explore the maternal body mass index (BMI) relationship with peripheral deiodinase activity further. Examine associations between deiodinase activity, glucose, and C-peptide. Consider findings in the historical context of related existing literature.

DESIGN

Identify fasting plasma samples and selected demographic, biophysical, and biochemical data from a subset of 600 randomly selected non-Hispanic white women recruited in the Hyperglycemia Adverse Pregnancy Outcomes (HAPO) study, all with glucose tolerance testing [545 samples sufficient to measure TSH, free T4 (fT4), and T3]. Exclude highest and lowest 1% TSH values (535 available for analysis). Assess deiodinase activity by using T3/fT4 ratios. Among women with and without gestational diabetes mellitus (GDM), compare thyroid measurements, C-peptide, and other selected data. Examine relationships independent of GDM status between BMI and thyroid hormones and between thyroid hormones and glucose and C-peptide.

RESULTS

Levels of BMI, T3/fT4 ratio, and T3 were significantly higher among women with GDM (P = 0.01, 0.005, and 0.001, respectively). Irrespective of GDM status, maternal BMI was associated directly with both T3/fT4 ratio (r = 0.40, P < 0.001) and T3 (r = 0.34, P < 0.001) but inversely with fT4 (r = -0.21, P < 0.001). In turn, fasting thyroid hormone levels (most notably T3/fT4 ratio) were directly associated with maternal glucose [z score sum (fasting, 1, 2 hours); r = 0.24, P < 0.001] and with C-peptide [z score sum (fasting, 1 hour); r = 0.27, P < 0.001].

CONCLUSIONS

Higher BMI was associated with increased deiodinase activity, consistent with reports from elsewhere. Increased deiodinase activity, in turn, was associated with higher glucose. Deiodinase activity accounts for a small percentage of z score sum glucose.

Comparison of irisin hormone expression between thyroid cancer tissues and oncocytic variant cells

Objective: The incidence of thyroid cancer has been continuously increasing. The main objective of this study was to investigate irisin expression in various thyroid pathologies and to compare these expression patterns with irisin expression in healthy thyroid tissues.

Methods: The study groups consisted of 20 cases each of control thyroid tissue, Hashimoto’s thyroiditis, thyroid papillary carcinoma, oncocytic papillary carcinoma, follicular thyroid carcinoma, oncocytic follicular thyroid carcinoma, medullary thyroid carcinoma, anaplastic thyroid carcinoma. Irisin expression was evaluated using immunohistochemistry. Irisin levels in thyroid tissue supernatants were measured using ELISA.

Results: Patients with HT showed increased irisin expression compared with controls (p<0.05). In addition, mild immunoreactivity was observed in the thyroid tissues of patients with papillary carcinoma while significantly increased irisin immunoreactivity was observed tissues of patients with oncocytic papillary carcinoma (p<0.05). There was no difference in irisin immunoreactivity in thyroid tissues between patients with follicular carcinoma and controls. However, irisin immunoreactivity was higher in tissues of patients with oncocytic follicular carcinoma than in tissues of patients with follicular carcinoma (p<0.05). No irisin immunoreactivity was observed in tissues of patients with medullary carcinoma, a malignant tumor the thyroid; however, irisin expression was significantly increased in tissues of patients with anaplastic carcinoma compared with that in tissues of controls (p<0.05). Furthermore, in all thyroid tissues with irisin expression, irisin immunoreactivity was observed in follicular cells, indicating that irisin is produced by these cells.

Conclusion: Irisin is a novel potential immunohistochemical marker for differentiating oncocytic variants of papillary and FTCs from papillary and follicular thyroid cancers.

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.

High-normal serum thyrotropin levels and increased glycemic variability in type 2 diabetic patients

PURPOSE

High-normal thyrotropin (TSH) is related to reduced insulin sensitivity and may contribute to glycemic disorders in diabetes. We investigated the relationship between normal serum TSH levels and glycemic variability in euthyroid type 2 diabetic patients.

METHODS

A total of 432 newly diagnosed type 2 diabetic patients with euthyroid function and normal serum TSH levels were recruited between March 2013 and February 2017. Insulin sensitivity was evaluated by the Matsuda index (ISI_Matsuda) following a 75-g oral glucose tolerance test. Multiple glycemic variability indices, including the mean amplitude of glycemic excursions (MAGE), mean of daily differences (MODD), and standard deviation of glucose (SD), were calculated from glucose data obtained with a continuous glucose monitoring system. Average glucose accessed by 24-h mean glucose (24-h MG) was also calculated.

RESULTS

A normal serum TSH level was positively correlated with MAGE, MODD, SD, and 24-h MG (r = 0.206, 0.178, 0.186, and 0.132, respectively, p < 0.01). After adjusting for somatometric parameters, lipid profiles, ISI_Matsuda, and HbA1c via multiple linear regression analysis, mean differences [B(95% CI)] in MAGE, MODD, SD, and 24-h MG between the patients in the lowest and highest quartiles of TSH levels were 0.128(0.031, 0.226), 0.085(0.022, 0.148), 0.039(0.001, 0.078), and 0.002(-0.264, 0.267) mmol/L, respectively. High-normal TSH was independently associated with MAGE, MODD, and SD, but not 24-h MG.

CONCLUSIONS

High-normal serum TSH is a significant additional risk factor for increased glycemic variability in type 2 diabetic patients.

Ectopic thyroid of the pancreas: A case report and literature review

RATIONALE

Ectopic thyroid is commonly found in the neck region. Intra-abdominal ectopic thyroid is extremely rare, with only 2 cases reported in the pancreatic region. Very few reports have described detailed imaging findings of intra-abdominal ectopic thyroid.

PATIENT CONCERNS

A 73-year-old woman with aggravated recurrent right upper quadrant pain was found to have a retroperitoneal mass at the head of pancreas. Abdominal computed tomography (CT) showed a well-defined, high attenuated (56HU) mass measured of 60 × 50 mm in diameter, that exhibited heterogeneous contrast enhancement throughout the 3 phases.

DIAGNOSIS

Neuroendocrine neoplasm was suspected.

INTERVENTIONS

Following discussions with the patient, she refused fine needle aspiration cytology; however, she underwent total resection of the mass and had an uneventful clinical course. Histopathological examination showed thyroid tissue with TTF-1 and TGB positivity, and BRAF negativity, indicating a benign variant.

OUTCOMES

The patient had no signs of relapse with normal thyroid hormone levels after 2 years of follow up.

LESSONS

Ectopic thyroid tissue should be considered when patients present with similar imaging findings in abdomen. We review all reported cases of abdominal ectopic thyroid tissue to provide specific evidence for the diagnosis and treatment of this rare entity.

Peripheral deiodinase activity: A potential explanation for the association between maternal weight and gestational hyperglycemia

Background

High maternal weight is known to associate with both low free thyroxine and gestational diabetes mellitus. We explore a deiodinase-related mechanism that may help explain these associations.

Methods

Among 108 women receiving routine oral glucose tolerance testing for gestational diabetes mellitus, we collected biophysical data and measured free thyroxine and total triiodothyronine, using residual plasma samples.

Results

Fasting triiodothyronine/free thyroxine ratio and triiodothyronine were higher among women with gestational diabetes mellitus (p = 0.02; p = 0.04). The triiodothyronine/free thyroxine ratio and triiodothyronine measurements at 2 h were associated with weight (r = 0.20, p = 0.04; r = 0.22, p = 0.02); free thyroxine showed a non-significant inverse weight relationship (r = -0.06, p = 0.55). Glucose at all four intervals was associated with triiodothyronine/free thyroxine ratios, and triiodothyronine at 2 h. In stepwise regression, triiodothyronine/free thyroxine ratio predicted glucose more strongly than did weight.

Conclusion

These relationships may be explained by higher maternal weight inducing peripheral deiodinase activity, resulting in higher plasma glucose (via triiodothyronine stimulation) and thereby increasing gestational diabetes mellitus risk.

High dose of radioactive iodine per se has no effect on glucose metabolism in thyroidectomized rats

PURPOSE

Thyroid concentrates radioactive iodine by sodium-iodide symporter; this is used for treating hyperthyroidism and thyroid cancer. Pancreas expresses NIS and radioactive iodine uptake may damage pancreatic beta-cells and predispose patients to type 2 diabetes. The aim of this study was to determine whether radioactive iodine is associated with glucose metabolism in thyroidectomized rats.

METHODS

Forty male Wistar rats were divided into four groups (n = 10/each); control, thyroidectomized, thyroidectomized-treated with 131-I (TX+I), and thyroidectomized-treated with 131-I and L-thyroxine (TX+I+T₄). At the end of study, serum fasting glucose, insulin, thyroid-stimulating hormone, and free tetraiodothyronine were measured, intraperitoneal glucose tolerance test was performed, and homeostasis model assessment-insulin resistance was calculated. In in vitro experiments, glucose-stimulated insulin secretion from pancreatic islets and sodium-iodide symporter mRNA expression in thyroid and islets were determined.

RESULTS

Compared to control group, free tetraiodothyronine was lower by 41 and 77% and thyroid-stimulating hormone was higher by 36 and 126% in thyroidectomized and TX+I groups, respectively. Compared to controls, rats in TX+I group had glucose intolerance as assessed using the area under curve of intraperitoneal glucose tolerance test (12,376 ± 542 vs. 20,769 ± 1070, P < 0.001) and L-thyroxine replacement therapy restored the value (14,286 ± 328.24) to near normal. Fasting insulin and homeostasis model assessment-insulin resistance were comparable in all groups, however fasting glucose was higher in TX+I group. In in vitro experiments, glucose-stimulated insulin secretion from islets did not differ between groups.

CONCLUSION

Radioactive iodine therapy per se had no effect on glucose metabolism, just intensified thyroid hormone deficiency and the alterations on glucose metabolism in thyroidectomized rats. L-thyroxine therapy restored the glucose intolerance observed in radioactive iodine-treated thyroidectomized rats.

Comparison of thyroid function tests and blood count in pregnant women with versus without gestational diabetes mellitus

AIM

The aim of this study was to compare thyroid function and complete blood count parameters in pregnant women with versus without gestational diabetes mellitus (GDM).

METHODS

A total of 269 pregnant women patients with (n = 110, GDM group) or without (n = 159, non-GDM group) GDM were included in this study. Data on age, rate of cesarean section, birthweight of neonate, hemogram, and thyroid function tests were collected. Multivariate analysis was performed to determine factors predicting increased risk of GDM.

RESULTS

Rate of cesarean section (70.9 vs 57.2%, P = 0.022), median (max-min) age (33.0 [26.0] vs 26.0 [20.0] years, P < 0.001), platelet count (246.7 ± 68.3 vs 227.8 ± 64.2 ×10³ /μL, P = 0.021) and thyroid-stimulating hormone (1.3 [97.6] vs 1.0 [4.1] μIU/mL, P = 0.028) were significantly higher in the GDM than in the non-GDM group; whereas mean platelet volume (10.4 [5.3] vs 10.6 [5.6] fL, P = 0.031) and free triiodothyronine (FT3) (2.9 [3.6] vs 3.1 [3.0] pg/mL, P < 0.001) levels were significantly lower in the GDM than in the non-GDM group. Older age (odds ratio, 1.281; 95% confidence interval, 1.182-1.389, P < 0.001) and lower FT3 levels (odds ratio, 0.295; 95% confidence interval, 0.149-0.586, P < 0.001) were independently associated with increased risk of GDM.

CONCLUSION

Our findings revealed that lower FT3 levels and older age predict the likelihood of developing GDM in euthyroid pregnant women, with no influence of other thyroid hormones or blood counts on the risk of GDM.

Free Thyroxine During Early Pregnancy and Risk for Gestational Diabetes

Several studies have now reported associations between gestational diabetes mellitus (GDM) and low free thyroxine (fT4) during the second and third trimesters, but not in the first trimester. The present study further examines relationships between low fT4, maternal weight, and GDM among women in the FaSTER (First and Second Trimester Evaluation of Risk) trial, in an effort to determine the extent to which thyroid hormones might contribute to causality. The FaSTER cohort includes 9351 singleton, euthyroid women; 272 of these women were subsequently classified as having GDM. Thyrotropin (TSH), fT4, and thyroid antibodies were measured at 11–14 weeks’ gestation (first trimester) and 15–18.9 weeks’ gestation (second trimester). An earlier report of this cohort documented an inverse relationship between fT4 in the second trimester and maternal weight. In the current analysis, women with GDM were significantly older (32 vs. 28 years) and weighed more (75 vs. 64.5 kg). Maternal weight and age (but not TSH) were significantly associated univariately with fT4 (dependent variable), in the order listed. Second trimester fT4 odds ratios (OR) for GDM were 2.06 [95% CI 1.37–3.09] (unadjusted); and 1.89 [95% CI 1.26–2.84] (adjusted). First trimester odds ratios were not significant: OR 1.45 [95%CI 0.97–2.16] (unadjusted) and 1.11 [95% CI 0.74–1.62] (adjusted). The second trimester fT4/GDM relationship thus appeared to strengthen as gestation progressed. In FaSTER, high maternal weight was associated with both low fT4 and a higher GDM rate in the second trimester. Peripheral deiodinase activity is known to increase with high caloric intake (represented by high weight). We speculate that weight-related low fT4 (the metabolically inactive prohormone) is a marker for deiodinase activity, serving as a substrate for conversion of fT4 to free triiodothyronine (fT3), the active hormone responsible for glucose-related metabolic activity.

Implications of High Free Thyroxine (FT4) concentrations in euthyroid pregnancies: the FaSTER trial

CONTEXT

Lower birth weight has been reported in conjunction with high maternal free T4 (FT4) in euthyroid pregnancies, raising concerns for suboptimal outcomes.

OBJECTIVE

The objective of the study was to explore the relationships between high maternal FT4 and pregnancy complications in euthyroid women and to further examine the relationships among maternal size, FT4, and birth weight.

DESIGN

This was an observational multicenter cohort study.

SETTING

The study was conducted at prenatal clinics.

STUDY SUBJECTS

A total of 9209 euthyroid women with singleton pregnancies participated in the study.

INTERVENTIONS

There were no interventions.

MAIN OUTCOME MEASURES

Relationships between second-trimester high maternal FT4 and pregnancy/delivery complications and, among FT4, maternal weight and birth weight were measured.

RESULTS

Women in the highest FT4 quintile are younger and weigh less than women in quintiles 1-4; gestational diabetes and preeclampsia occur less often (P = < .001, P < .001, P < .001, and P = .05, respectively). Lowest median birth weight occurs among women in the highest FT4 quintile (P = < .001), but deliveries less than 37 weeks' gestation are not increased. Labor/delivery complications do not differ by FT4 quintile. Restricting analyses to maternal weight-adjusted small-for-gestational-age deliveries yields similar results, except for preeclampsia. In the highest maternal weight decile, adjusted median birth weight is 266 g higher (8.3%) than in the lowest weight decile; adjusted median FT4 is 0.91 pmol/L lower (6.8%). Among women in the highest FT4 decile, adjusted median birth weight is 46 g lower (1.3%) than in the lowest FT4 decile. All three relationships are statistically significant (P < .001, P < .001, and P = .004, respectively).

CONCLUSIONS

Lower median birth weight among euthyroid women with high FT4 is not associated with adverse pregnancy outcomes. Further investigation is indicated to determine how the variations in thyroid hormone concentration influence birth weight.

Relationship of subclinical thyroid disease to the incidence of gestational diabetes

OBJECTIVE

To estimate if there is a relationship between subclinical thyroid disease and gestational diabetes.

METHODS

Between November 2000 and April 2003, serum thyrotropin screening was performed on all women who presented for prenatal care. Women identified with abnormal thyrotropin had a serum free thyroxine reflexively determined. Those women with abnormal serum free thyroxine values were referred for further evaluation and excluded from further analysis. For this analysis, normal thyrotropin values were those between the 2.5th and 97.5th percentiles (0.03-4.13 milliunits/L) not corrected for gestational age and serum free thyroxine were considered normal if they ranged from 0.9 to 2.0 mg/dL. Women with an elevated serum thyrotropin but a normal serum free thyroxine were designated to have subclinical hypothyroidism and those with a low thyrotropin and a normal serum free thyroxine level were designated to have subclinical hyperthyroidism. Euthyroid women had both normal thyrotropin and normal serum free thyroxine values. The incidence of gestational diabetes was compared among these three groups.

RESULTS

Of the 24,883 women included in the study, 23,771 (95.5%) were euthyroid, 584 (2.3%) had subclinical hyperthyroidism, and 528 (2%) had subclinical hypothyroidism. The likelihood of gestational diabetes increased with thyrotropin level (P=.002). For example, when a pregnant Hispanic woman of average age and weight was used, the predicted percent of gestational diabetes increased from 1.9% to 4.9% as thyrotropin increased from 0.001 to 10 milliunits/L (P=.001).

CONCLUSION

The risk of developing gestational diabetes increases with thyrotropin level. This supports a relationship between subclinical hypothyroidism and diabetes diagnosed during pregnancy.

LEVEL OF EVIDENCE

III.

Diabetes and thyroid cancer risk: literature review

Diabetic patients have a higher risk of various types of cancer. However, whether diabetes may increase the risk of thyroid cancer has not been extensively studied. This paper reviews and summarizes the current literature studying the relationship between diabetes mellitus and thyroid cancer, and the possible mechanisms linking such an association. Epidemiologic studies showed significant or nonsignificant increases in thyroid cancer risk in diabetic women and nonsignificant increase or no change in thyroid cancer risk in diabetic men. A recent pooled analysis, including 5 prospective studies from the USA, showed that the summary hazard ratio (95% confidence interval) for women was 1.19 (0.84-1.69) and was 0.96 (0.65-1.42) for men. Therefore, the results are controversial and the association between diabetes and thyroid cancer is probably weak. Further studies are necessary to confirm their relationship. Proposed mechanisms for such a possible link between diabetes and thyroid cancer include elevated levels of thyroid-stimulating hormone, insulin, glucose and triglycerides, insulin resistance, obesity, vitamin D deficiency, and antidiabetic medications such as insulin or sulfonylureas.

Do antidiabetic medications play a specific role in differentiated thyroid cancer compared to other cancer types?

The risk for differentiated thyroid cancer, like for many other types of cancer, is increased in obese individuals and people with intermediate hyperglycaemia. The incidence of all cancers, with the exception of thyroid cancer, is also increased in type 2 diabetes mellitus patients. The review compares the prevalence of thyroid carcinoma and other cancers in obese, people with intermediate hyperglycaemia and patients with diabetes and summarizes mode of action and anti-tumourigenic effect of common antidiabetic medications. The over-expression of dipeptidyl peptidase IV in the tumours, not seen in the other cancer types, is suggested as a potential reason for the unique situation in thyroid cancer.

Thyroid-related autoantibodies in Tunisian patients with type 1 diabetes

AIM

To evaluate, retrospectively, the frequency of antithyroid antibodies (ATA) in patients with type 1 diabetes (T1D).

MATERIALS AND METHODS

Antithyroperoxidase antibodies (TPO-Ab), antithyroglobulin antibodies (TG-Ab), and antithyroid-stimulating hormone receptor antibodies (TSHR-Ab) were determined by enzyme-linked immunosorbent assay. Sera of 312 patients (166 children and 146 adults) with T1D were analyzed. Sera of 276 healthy subjects (87 children and 189 blood donors) served as controls.

RESULTS

Out of 312 patients with T1D, 44 (14%) had ATA (TPO-Ab or TG-Ab or TSHR-Ab). The frequency of ATA in patients with T1D was significantly higher than in the control group (14% vs. 2.8%; p<10(-5)). ATA were significantly more frequent in adult patients with T1D than in the blood donor group (20% vs. 1.6%; p<10(-8)). The frequency of ATA in adult patients was significantly higher than in pediatric patients (20% vs. 9%; p=0.006). The frequency of TPO-Ab and TG-Ab was significantly higher in patients with T1D than in the control group (13.5% vs. 2%; p<10(-8) and 7% vs. 2.2%, p=0.008), respectively. Out of 312 patients with T1D, only one had TSHR-Ab. The simultaneous presence of three autoantibodies was found in one patient with T1D.

CONCLUSION

ATA were frequent in patients with T1D. Serological screening of autoimmune thyroid disease is suggested in patients with T1D.