| Objective:Recent studies have shown that patients with type 2 diabetes mellitus（T2DM）are more prone to vitamin D（Vit D）deficiency or insufficiency compared to the healthy population,and Vit D deficiency may be involved in the development and progression of T2DM.As a fat-soluble steroid hormone,vitamin D has attracted increasing attention for its effects beyond the skeleton.There have been many studies linking serum vitamin D to autoimmune diseases such as type 1 diabetes,Hashimoto’s thyroiditis and newonset Graves’ disease,however,there is a lack of clear clinical data on the effect of Vit D on thyroid function in thyroid antibody-negative T2DM patients.The main indicator of the body’s Vit D level is the concentration of its circulating metabolite serum 25-hydroxyvitamin D [25（OH）D] concentration.The aim of this study was to investigate the relationship between serum 25（OH）D levels and thyroid function in patients with T2DM.Methods:Two hundred and sixty patients with type 2 diabetes mellitus,153 males and 107 females,who were hospitalized in China-Japan Hospital of Jilin University from May2021 to December 2021,were selected for the study.The serum 25（OH）D was measured by chemiluminescence immunoassay and divided into 4 groups according to the serum 25（OH）D concentration: 32 cases in the 25（OH）D normal group（≥30 ng/m L）,85 cases in the 25（OH）D insufficiency group（20 ～ <30 ng/m L）,105 cases in the25（OH）D deficiency group（10 ～ <20 ng/m L）,and 38 cases in the 25（OH）D severely deficiency group（<10 ng/m L）.The basic data of the enrolled patients were collected:gender,age,height,weight,history of smoking,history of alcohol consumption,systolic blood pressure,diastolic blood pressure,duration of diabetes mellitus,history of coronary heart disease;clinical biochemical indexes including fasting blood glucose（FPG）,glycosylated hemoglobin（Hb A1c）,fasting C-peptide（FCP）,triglycerides（TG）,total cholesterol（TC）,25（OH）D blood calcium（Ca）,blood phosphorus（P）,parathyroid hormone（PTH）,thyroid stimulating hormone（TSH）,free triiodothyronine（FT3）,free thyroxine（FT4）,triiodothyronine（T3）,thyroxine（T4）,anti-thyroid peroxidase antibody（TPOAb）,and anti-thyroglobulin antibody（Tg Ab）.The data were processed using SPSS 26.0 statistical software to compare the differences in the indexes of the four groups and to analyze the effects of different levels of 25（OH）D on the thyroid function of patients with T2DM.Results:1.The duration of T2DM in the 25（OH）D insufficiency group,25（OH）D deficiency group,and 25（OH）D severe deficiency group was significantly higher than that in the25（OH）D normal group,the difference was statistically significant（P<0.05）.There was no statistically significant difference in the comparison of general data of the 4 groups in terms of gender,age,smoking history,drinking history,BMI,systolic blood pressure,diastolic blood pressure and history of coronary heart disease（P>0.05）.2.The TSH level in the 25（OH）D severe deficiency group was significantly higher than that in the 25（OH）D normal group,with statistically significant differences（P<0.05）,and the FT3 level in the 25（OH）D severe deficiency group and the 25（OH）D insufficiency group was significantly lower than that in the 25（OH）D normal group,with statistically significant differences（P<0.05）.The differences were not statistically significant when comparing T3,FT4,T4,TPOAb and Tg Ab in the 4 groups（P>0.05）.3.The insulin resistance index of 25（OH）D deficiency group and 25（OH）D severe deficiency group was significantly lower than that of 25（OH）D normal group,and the difference was statistically significant（P<0.05）;the fasting C-peptide of 25（OH）D deficiency group and 25（OH）D severe deficiency group was higher than that of25（OH）D normal group,and the difference was statistically significant（P<0.05）;the differences in FPG,Hb A1 c,Ca,P,PTH,TG and TC were not statistically significant（P>0.05）when comparing the 4 groups of patients.4.Pearson correlation analysis between 25（OH）D and metabolic indicators of thyroid function showed that 25（OH）D was significantly negatively correlated with TSH（correlation coefficient r=-0.329,P<0.001）.5.A univariate correlation analysis of TSH with all study variables was performed first,and the results showed that the duration of diabetes,insulin resistance index and25（OH）D were correlates of TSH concentration in patients with T2DM.TSH level was included as the dependent variable and 25（OH）D,duration of diabetes mellitus,insulin resistance index and factors that have been previously studied to have an impact on outcome（female,advanced age,obesity,insulin resistance,TPOAb positive,Tg Ab positive,poor glycemic control）were included as independent variables in the multiple linear regression analysis,and the results showed that 25（OH）D（P<0.001）,and insulin resistance index（P<0.05）were independent risk factors for predicting elevated TSH concentrations in patients with T2DM.Conclusion:There was a negative correlation between serum 25（OH）D and TSH concentrations in T2DM patients,and 25（OH）D（P<0.001）and insulin resistance index（P<0.05）were independent risk factors predicting elevated TSH concentrations in T2DM patients. |
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