Hypothyroidism has no impact on insulin sensitivity assessed with HOMA-IR in totally thyroidectomized patients

The influence of thyroid hormones on insulin and glucose metabolism is controversial. We examined the impact of hypothyroidism on insulin sensitivity in 22 hypothyroid patients (15 females and 7 males, mean age 51.0 +/- 12.36 yrs). All subjects had a history of total thyroidectomy and radioiodine ablation for differentiated thyroid cancer. Each subject ceased levothyroxine treatment six weeks prior to admission. The controls were 17 healthy individuals, 6 women and 11 men, mean age 55.12 +/- 14.17 years. TSH, free thyroxine, and the HOMA index of insulin sensitivity, as well as HOMA B (%) and HOMA S (%) were assessed. Insulin sensitivity was compared between the groups, and the correlation between FT4 and TSH and insulin sensitivity was calculated.

The mean FT4 was 4.6 +/- 4.64 pmol/L in the examined group vs. 16.2 +/- 1.8 pmol/L in controls, p<005; TSH 72.11 +/- 36.73 pmol/L vs. 1.24 +/- 1.07 pmol/L, p<0.005; plasma glucose 4.68 +/- 0.47 mmol/L vs. 5.04 +/- 0.62mmol/L, p=0.0436; plasma insulin 8.07 +/- 9.39 microU/mL vs. 7.24 +/- 4.06 microU/mL, p=0.7877; HOMA index 1.79 +/- 2.53 vs. 1.69 +/- 1.09, p=0.5148; HOMA B (%) 102.46 +/- 41.59 vs. 85.95 +/- 26.87, p=0.1926, and HOMA S (%) 150.46 +/- 95.90 vs. 153.80 +/- 108.85, p= 0.6710, in subjects and controls, respectively. The levels of insulin sensitivity did not differ significantly between the two groups. FT4 and TSH did not influence the insulin sensitivity in either group, the correlation was insignificant, respectively p=0.5426 and p=0.8175 in the examined group, and p=0.172 and p=0.4509 in the controls.

Hypothyroidism has no impact on insulin sensitivity in the examined group.