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

J Diabetes. 2021 Apr;13(4):318-329. doi: 10.1111/1753-0407.13118. Epub 2020 Nov 2.

Abstract

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

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

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

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

目的: 探讨2型糖尿病(T2DM)患者甲状腺功能与糖代谢的关系, 进一步研究T2DM患者经国家代谢管理中心(MMC)管理后甲状腺功能的变化。 方法: 研究纳入上海市第一人民医院MMC甲状腺功能正常人群及社区健康体检人群共2000例, 分为4组:糖耐量正常组(n=132), 糖尿病前期组(n=147), 糖尿病控制良好组(T2DM糖化血红蛋白≤7%, n=505), 糖尿病控制不良组(T2DM糖化血红蛋白>7%, n=1216), 比较各组间相关代谢指标, 并进一步观察糖尿病控制不良组经MMC随访前后甲状腺功能的变化。 结果: 四组间游离三碘甲状腺原氨酸(FT3)和游离甲状腺素(FT4)水平差异显著。FT3, FT4水平与HbA1c水平呈负相关(P <0.05), 与预估葡萄糖清除率(eGDR)呈正相关(P <0.05)。MMC管理后, 糖尿病控制不良组血糖和胰岛素抵抗明显改善(P <0.001)。同时, 与基线相比, FT3升高(从4.51±0.78 pmol/L升至4.68±0.87 pmol/L, P <0.05), 反三碘甲状腺原氨酸(r-t3)从1.03±0.24 nmol/L降至0.92±0.25 nmol/L(P<0.001)。促甲状腺激素(TSH)也明显降低(P <0.001)。 结论: 正常范围内游离甲状腺激素水平降低与高血糖和胰岛素抵抗有关。MMC管理后, 血糖和胰岛素抵抗的改善也伴随着甲状腺功能的恢复。.

Keywords: 2型糖尿病; insulin resistance; metabolic management center; thyroid function; type 2 diabetic mellitus; 代谢性疾病管理中心; 甲状腺功能; 胰岛素抵抗.

MeSH terms

  • Adult
  • Aged
  • Biomarkers / blood
  • Blood Glucose / metabolism*
  • Case-Control Studies
  • China
  • Cross-Sectional Studies
  • Diabetes Mellitus, Type 2 / blood
  • Diabetes Mellitus, Type 2 / diagnosis
  • Diabetes Mellitus, Type 2 / physiopathology
  • Diabetes Mellitus, Type 2 / therapy*
  • Female
  • Glycated Hemoglobin / metabolism
  • Humans
  • Insulin Resistance*
  • Male
  • Middle Aged
  • Prediabetic State / blood
  • Prediabetic State / diagnosis
  • Prediabetic State / physiopathology
  • Prediabetic State / therapy*
  • Prospective Studies
  • Thyrotropin / blood*
  • Thyroxine / blood*
  • Time Factors
  • Treatment Outcome
  • Triiodothyronine / blood*

Substances

  • Biomarkers
  • Blood Glucose
  • Glycated Hemoglobin A
  • hemoglobin A1c protein, human
  • Triiodothyronine
  • Thyrotropin
  • Thyroxine