Table 2 Relationship between thyroid hormone levels and insulin resistance.

From: Low total and free triiodothyronine levels are associated with insulin resistance in non-diabetic individuals

Thyroid hormone Total (N = 1560) Univariate Multivariate
Coefficient (95% CI) Coefficient (95% CI)
Thyroid stimulating hormone (TSH) (mIU/L) 2.01 ± 0.08   
  Normal (0.24–5.4 mIU/L) 1506 (97.0) Reference Reference
  Low (<0.24 mIU/L) 16 (0.8) −0.632 (−1.291, 0.027) −0.564 (−1.288, 0.161)
  High (>5.4 mIU/L) 38 (2.2) 0.228 (−0.606, 1.061) 0.204 (−0.418, 0.827)
Total triiodothyronine (TT3) (ng/dL) 115.69 ± 1.01   
  Normal (87–178 ng/dL) 1445 (93.0) Reference Reference
  Low (<87 ng/dL) 97 (6.1) −0.747 (−1.199, −0.294) −0.486 (−0.936, −0.036)
  High (>178 ng/dL) 18 (0.9) 0.661 (−0.321, 1.643) 0.586 (−0.211, 1.382)
Free triiodothyronine (FT3) (pg/mL) 3.27 ± 0.02   
  Normal (2.5–3.9 pg/mL) 1470 (94.3) Reference Reference
  Low (<2.5 pg/mL) 15 (0.7) −0.647 (−1.493, 0.198) −1.151 (−1.952, −0.35)
  High (>3.9 pg/mL) 75 (5.0) 0.206 (−0.088, 0.501) −0.092 (−0.449, 0.265)
Total thyroxine (TT4) (ug/dL) 7.69 ± 0.06   
  Normal (6.1–12.2 ug/dL) 1372 (86.6) Reference Reference
  Low (<6.1 ug/dL) 174 (12.7) −0.141 (−0.553, 0.270) −0.054 (−0.347, 0.240)
  High (>12.2 ug/dL) 14 (0.7) 0.056 (−0.693, 0.806) −0.214 (−0.632, 0.203)
Free thyroxine (FT4) (ng/dL) 0.78 ± 0.01   
  Normal (0.6–1.6 ng/dL) 1532 (97.9) Reference Reference
  Low (<0.6 ng/dL) 25 (2.0) 1.925 (0.233, 3.617) 1.372 (−0.282, 3.025)
  High (>1.6 ng/dL) 3 (0.1) −0.606 (−1.389, 0.178) −1.857 (−4.102, 0.387)
Thyroglobulin (ng/mL) 15.49 ± 0.95   
  Normal (0–35.0 ng/mL) 1446 (93.5) Reference Reference
  High (>35.0 ng/mL) 114 (6.5) 0.715 (−0.062, 1.492) 0.523 (−0.373, 1.418)
Thyroid peroxidase antibodies (IU/mL) 16.62 ± 1.85   
  Normal (0–9.0 IU/mL) 1422 (90.3) Reference Reference
  High (>9.0 IU/mL) 138 (9.7) −0.022 (−0.472, 0.429) 0.008 (−0.266, 0.282)
  1. CI, confidence interval.
  2. Bold indicates significant factor, p < 0.05.
  3. Thyroid hormone levels were shown mean ± standard error; thyroid hormone group numbers were shown unweighted counts (weighted %).
  4. Multivariate model: Adjusted for thyroid hormones, race, liver function, depression, obesity, hypertension, dyslipidemia, smoking, physical activity, vigorous recreational activity, moderate recreational activity, 2-hour glucose, glycohemoglobin, high-density lipoprotein, triglyceride, vitamin D, and C-reactive protein.