Thyroid Hormone Changes in Euthyroid Patients with Diabetes

Abstract

Background

Thyroid dysfunction is associated with diabetes, but it is unclear if the thyroid hormone levels change in euthyroid adults with diabetes.

Objective

To investigate the association between thyroid hormone levels and diabetes in euthyroid adults.

Methods

Among the euthyroid adults who underwent health examination in West China Hospital of Sichuan University in 2016, patients with diabetes were identified according to the medical history, fasting blood glucose and HbA1c. Age and sex matched controls were identified from the population. The patients with diabetes group was further divided into two subgroups: patients with newly diagnosed diabetes (NDD) and with previously diagnosed diabetes (PDD). Independent t-test and multivariate logistic regression models were used to investigate the difference in the levels of thyroid stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3) and the ratio of FT4/FT3 between groups.

Results

We included 32,557 participants, 2,271 with diabetes. Compared to the adults without diabetes, the odds ratios (ORs) per one unit elevation of TSH, FT4, FT4/FT3 ratio and FT3 in patients with diabetes were 0.88 [95% confidence interval (CI): 0.82–0.95], 1.11 (95% CI: 1.08–1.14), 2.05 (95% CI: 1.81–2.32) and 0.85 (95% CI: 0.78–0.93), respectively. Compared to the NDD group, the ORs per one unit elevation of TSH, FT4, FT4/FT3 ratio and FT3 of the PDD group were 0.81 (95% CI: 0.71–0.92), 1.08 (95% CI: 1.04–1.12), 1.76 (95% CI: 1.49–2.08) and 1.01 (95% CI: 0.92–1.12), respectively.

Conclusion

In euthyroid adults, diabetes was associated with increased FT4/FT3 ratio, which is linked to the peripheral turnover of the thyroid hormones.

Keywords:

• diabetes mellitus
• thyroid hormones
• triiodothyronine
• thyroxine

Abbreviations

NDD, newly diagnosed with diabetes; PDD, previously diagnosed with diabetes; TSH, thyroid stimulating hormone; FT4, free thyroxine; FT3, free triiodothyronine; ORs, odds ratios; CI, confidence interval; TPOAb, thyroid peroxidase antibody; TGAb, thyroglobulin antibody; HbA1c, hemoglobin A1c; COPD, chronic obstructive pulmonary disease; eGFR, estimated glomerular filtration rate; BMI, body mass index; FPG, fasting plasma glucose; TG, triglyceride; LDL-C, low-density lipoprotein cholesterol; HDL-C, high-density lipoprotein cholesterol; ALT, alanine aminotransferase; AST, aspartate aminotransferase; GGT, glutamyl transpeptidase; DBP, diastolic blood pressure; SBP, systolic blood pressure; WC, waist circumstance; DM, diabetes mellitus; rT3, reverse triiodothyronine; D1, type 1 deiodinases; ESS, euthyroid sickness syndrome; T4, tetraiodothyronine; T3, triiodothyronine.

Data Sharing Statement

The datasets used and/or analyzed during the current study are available from the corresponding author, Sheyu Li, on reasonable request.

Ethics Approval and Consent to Participate

This study is approved by the ethical committee of West China Hospital, Sichuan University (No. 2015-202). Subjects were only included if they signed informed consent agreeing to the scientific use of their health data.

Author Contributions

All authors made substantial contributions to conception and design, acquisition of data, or analysis and interpretation of data; took part in drafting the article or revising it critically for important intellectual content; gave final approval of the version to be published; and agree to be accountable for all aspects of the work.

Disclosure

The authors have no conflicts of interest to declare.

Additional information

Funding

This study was supported by 1.3.5 Project for Disciplines of Excellence, West China Hospital, Sichuan University (grant number ZYGD18022) and Sichuan Science and Technology Program (grant numbers 2017RZ0046, 2018SZ0087 and 2019YFH0150). Sheyu Li has also received grants from the National Natural Science Foundation of China (grant number 81400811 and 21534008).