Study on serum thyroid hormone and thyrotropin levels and influencing factors in patients with type 2 diabetes mellitus

ObjectiveTo investigate the changes of serum thyroid hormone(TH) and thyroid stimulating hormone(TSH) levels in patients with type 2 diabetes mellitus(T2DM) and their influencing factors.

MethodsSeventy-five patients with T2DM(T2DM group) and 75 healthy persons(control group) were selected to compare the levels of TH and TSH in serum of the two groups.The levels of TH and TSH in serum of the two groups were also compared according to sex, age, course of disease, HbAlc and FBG.

ResultsThe level of serum free triiodothyronine(FT3) in patients with T2DM was significantly lower than that in control group(P < 0.01).There was no significant difference in the levels of free thyroxine(FT4) and TSH between the two groups(P>0.05).There was no significant difference in serum FT3, FT4 and TSH levels between different sexes, taking metformin of not in T2DM patients(P>0.05).There were significant differences in serum FT3 levels between patients of different age groups and course of disease.With the increase of age and course of disease, the level of FT3 decreased(P < 0.05 to P < 0.01).There were statistical differences in FT3 and FT4 levels between patients with different HbAlc.The levels of FT3 and FT4 decreased with the increase of HbAlc(P < 0.05 to P < 0.01), and the levels of FT3 and FT4 in patients with FBG ≥ 7.0 mmol/L were significantly lower than those in patients with FBG < 7.0 mmo/L(P < 0.01).Spearman correlation analysis showed that FT3 level was negatively correlated with age, course of disease, HbAlc and FBG in patients with T2DM(P < 0.05), and FT4 was negatively correlated with HbAlc and FBG(P < 0.05).

ConclusionsCompared with healthy adults, patients with T2DM have abnormal thyroid function, which is mainly manifested by the decrease of FT3.The changes of FT3 level in patients with T2DM are closely related to age, course of disease, HbA1c and FBG.