Iodine Nutritional Status And Its Associated Factors In Patients With Type 2 Diabetes Mellitus

Objective:To survey the iodine nutritional status and to analyze its associated metabolic factors in patients with type 2 diabetes mellitus.Methods:There were 501 inpatients tested for urine iodine from November 2018 to November 2019,of which 456 were patients with type 2 diabetes mellitus.A total of 433patients were included for analysis after excluding hypothyroidism?n=3?,suspected central thyroid function abnormality?n=18?,and incomplete data?n=2?.Patients with type 2 diabetes mellitus were divided into subclinical hyperthyroidism?SCHypo,94 cases,21.7%?,normal thyroid function?ET,300 cases,69.3%?,subclinical hyperthyroidism?SCHyper,27 cases,6.2%?,and clinical hyperthyroidism?H,12 cases,2.8%?.After further excluding those of abnormal thyroid function and thyroid autoantibodies?thyroid globulin autoantibody,ATG,and thyroid peroxidase autoantibody,ATPO?,203 patients were used to analyze the association of iodine nutritional status with metabolic abnormalities and prevalence of thyroid nodules.There were 82 patients with different types of thyroid nodules,including solid nodules?SN,27 cases?,mixed nodules?MN,45cases?,and cystic nodules?CN,10 cases?.Iodine nutritional status was evaluated by UIC and urinary iodine/creatinine?UI/Cr?.Results:1.Gender,Fasting blood glucose?FBG?,HOMA-?,total cholesterol?TC?,Apolipoprotein B?Apo B?was significantly different(P_trend<0.05)and low density lipoprotein cholesterol?LDL-C?borderly different(P_trend=0.051)among Different thyroid functional status.SCHypo and SCHyper were more common in women.Levels of FBG and glycosylated hemoglobin?Hb A1c?in SCHyper were higher than other groups.SCHyper had worse?cell function?HOMA-??than EH and SCHypo,there was no difference in?cell function between H and SCHyper.SCHypo had the highest TC while H the lowest,and high-density lipoprotein cholesterol?HDL-C?was significantly decreased in H,the Apo B level SCHyper and H was lower than that of ET and SCHypo.2.UIC?ambient g/L?and UI/Cr?ambient g/g?levels were significantly different among different thyroid function states?P<0.05?.SCHypo had the higher UIC?206.19±147.15?,compared with ET?164.32±95.27?and SCHyper?149.00±134.73?,and UI/Cr in ET?170.75±96.31?was lower than that of SCHypo?240.70±172.02?.Regardless of thyroid function status,UIC level was lower in women than in men?P=0.031?,but there was no significant difference for UI/Cr?P=0.131?.3.There were 203 euthyroidic thyroid autoantibody negative patients with type 2diabetes mellitus.Pearson correlation analysis revealed that UIC was negatively correlated with LDL-C?r=-0.148,P=0.036?;UI/Cr was positively correlated with age?r=0.140,P=0.046?,insulin?INS??r=0.158,P=0.024?,HOMA-IR?r=0.201,P=0.004?and negatively correlated with Free Triiodothyronine?FT3??r=-0.152,P=0.030?and Free tetraiodothyronine?FT4??-0.197,P=0.005?.Spearman correlation analysis found that UIC was positively correlated with body mass index?BMI??r=0.158,P=0.027?and FBG?r=0.141,P=0.045?,and negatively correlated with serum Thyroid Stimulating Hormone?TSH??r=-0.175,P=0.013?and LDL-C?r=-0.142,P=0.045?.UI/Cr was positively correlated with age?r=0.165,P=0.019?,INS?r=0.152,P=0.030?and HOMA-IR?r=0.195,P=0.005?,and negatively correlated with FT3?r=-0.144,P=0.040?and FT4?r=-0.195,P=0.005?.After adjusted with gender,age,duration of diabetes?DD?,and estimated glomerular filtration rate?e GFR?and TSH,FT4,FT3,partial correlation analysis showed that UIC were positively correlated BMI?r=0.159,P=0.031?,UI/Cr were positively correlated with FBG?r=0.176,P=0.017?and HOMA IR?r=0.189,P=0.011?.4.Using UIC or UI/Cr as the dependent variable,and Age,time of disease,BMI,TSH,FT4,FT3,Hb A1c,FBG,Tchol,HDL-C,LDL-C,Apolipoprotein A?Apo A?,Apo B,log10?INS,Triglyceride?log10?TG?,log10-HOMA-IR,and log10?HOMA-?as covariates,stepwise linear regression analysis showed a linear correlation between UIC and BMI?P=0.027?.UI/Cr was linearly correlated with age and log?HOMA-IR?P<0.004?and age?0.001?.5.Using the minimum linear model of multivariate analysis,A trend of higher BMI?F=2.542,P=0.058?and higher C-peptide?log10?CP??F=2.645,P=0.051?were found from UIC standard of iodine deficiency to that of excess after adjusting for gender,age,DD,e GFR,BMI,TSH,FT4,and FT3;A trend of higher FBG and Log10?HOMA-IR?P<0.05?and a borderline trend of higher Log10?INS?P=0.076?were found from UI/Cr standard of iodine deficiency to that of excess.6.Eighty two patients were found with various nodules among the 203 euthyroidic thyroid antibody negative patients with type 2 diabetes.Cross-table Chi-square analysis found no statistically difference was found for prevalence of thyroid nodules among different UIC status and UI/Cr?P>0.05?.To compare the differences between iodine nutritional status and different types of nodules,thyroid nodules were divided into substantive?single or multiple?,mixed?both substantive and mixed,single or multiple?,and cystic?no substantive or mixed?nodules.Chi-square analysis did not find the difference in presence of different nodules under different iodine nutritional status?P>0.05?.7.To explore whether iodine nutritional status affects the presence of thyroid autoantibodies,a total of 300 patients with type 2 diabetes mellitus and normal thyroid function were included in the analysis with 97 patients with positive antibodies.Stratified by sex.Chi-square analysis found on significant difference in presence of thyroid autoantibodies under different status iodine nutritional status irrespective whether classified with UIC or with UI/Cr?P>0.05?.Conclusion:Excessive iodine intake may be related to subclinical hypothyroidism.Iodine excess may lead to worse blood glucose control and higher insulin resistance.Iodine nutritional status is not related to the production of thyroid nodules and thyroid autoantibodies in euthyroidic thyroid antibody negative patients with type 2 diabetes.