Study On The Relationship Between FT3 Level And NAFLD In Type 2 Diabetic Patients With Normal Thyroid Function

Background:Type 2 diabetes mellitus（T2DM）is a chronic metabolic disease characterized by hyperglycemia.Non-alcoholic fatty liver disease（NAFLD）is a clinical syndrome characterized by hepatocyte steatosis,which excludes viral infections,alcohol,drugs and other definite liver function impairment factors.The prevalence of NAFLD has been increasing in recent years,and patients with Diabetes mellitus（DM）often have NAFLD,and its prevalence has increased significantly compared with non-DM populations.At present,NAFLD has become an important cause of liver damage in patients with T2DM,making it more difficult to control plasma glucose.Thyroid hormone（TH）is an important hormone that regulates the body’s metabolism,widely acting on various tissues and organs of the body,especially playing an important role in the metabolism of glucose and lipids.In recent years,a number of studies have found that in people with normal thyroid function,TH level is significantly related to the risk of NAFLD.However,there are few studies on liver fat metabolism in T2DM patients with normal thyroid function,and the conclusions are not uniform.Therefore,it is necessary to further explore the relationship between TH level and the risk of NAFLD and its possible mechanism in T2DM population with normal thyroid function,so as to provide a theoretical basis for finding new therapeutic targets for DM combined with hepatic fat metabolism disorders.Objective:（1）Analyze the relationship between T2DM and NAFLD under normal thyroid function.（2）Analyze the correlation between thyroid function indexes and other clinical indexes in T2DM patients.（3）To explore the related influencing factors of NAFLD in T2DM patients with normal thyroid function.Methods:（1）This study took T2DM patients and/or NAFLD patients with normal thyroid function who were hospitalized in the Endocrinology Department and Gastroenterology Department of the First Affiliated Hospital of Guangdong Pharmaceutical University from December 2018 to July 2020 as the research objects.A retrospective analysis of the relevant clinical indicators of the study subjects that meet the criteria for inclusion.（2）Collect relevant data,including age,gender,height,weight,body mass index（BMI）,glycosylated hemoglobin（Hb A1c）,fasting plasma glucose（FPG）,2-hour postprandial plasma glucose（2h PG）,aspartame aminotransferase（AST）,alanine aminotransferase（ALT）,total cholesterol（TC）,triglycerides（TG）,low-density lipoprotein cholesterol（LDL-C）,high-density lipoprotein cholesterol（HDL-C）,free triiodothyronine（FT3）,free thyroxine（FT4）,thyroid stimulating hormone（TSH）,liver ultrasound.The plasma sampling test was performed in accordance with the quality control and inspection standards formulated by the First Affiliated Hospital of Guangdong Pharmaceutical University.（3）Use SPSS20.0 for statistical analysis.For measurement data,the normal distribution was described by x^_<sub>±s,and the t test was used for comparison between groups;the non-normal distribution was described by the median（quartile）[M（Q1,Q3）],and Mann-Whitney u test was used for comparison between groups.Enumeration data were described by percentage（%）or frequency（n）,andχ2 test was used for comparison between groups.Pearson correlation or Spearman rank correlation was used to analyze the correlation between thyroid function indexes and other clinical indexes.The binary logistic regression method was used to analyze the impact of various relevant clinical indicators in patients with T2DM on the risk of NAFLD.All tests are two-way tests,the statistical test levelα=0.05,P<0.05 considered the difference to be statistically significant.Results:（1）Comparison of research objects between groups（1）In T2DM patients,there was no statistical difference between NAFLD group and non-NAFLD group in age,gender,Hb A1c,FPG,2h PG,TC,LDL-C,HDL-C,FT3,FT4,TSH indicators（P>0.05）.The BMI,TG,ALT and AST of the NAFLD group significantly increased（P<0.05）.（2）In NAFLD patients,there was no statistical difference between T2DM group and non-T2DM group in age,gender,BMI,TG,TC,LDL-C,HDL-C,FT4,TSH,ALT,AST indicators（P>0.05）.The FPG of the T2DM group significantly increased（P<0.01）;the FT3 of the non-T2DM group significantly increased（P<0.01）.（2）Correlation analysis between thyroid function indexes and other clinical indexes in T2DM patientsSpearman correlation analysis showed that FT3 was positively correlated with BMI and TG（P<0.01）,and negatively correlated with Hb A1c（P<0.01）;FT4 was positively correlated with Hb A1c（P<0.05）;TSH was not correlated with any index（P>0.05）.（3）Binary logistic regression analysis with NAFLD as the dependent variableBinary logistic regression analysis was performed with NAFLD as the dependent variable,and the influence of confounding factors was excluded.BMI and TG were independent risk factors for T2DM patients with NAFLD.Conclusion:（1）In patients with T2DM,BMI,TG,ALT and AST in NAFLD group were significantly higher than those in non-NAFLD group,suggesting that obesity and disorder of lipid metabolism are the susceptible factors of NAFLD in T2DM patients with normal thyroid function,and finally lead to the damage of liver function.（2）In NAFLD patients,the FT3 in non-T2DM group was higher than that in T2DM group,while in T2DM patients,there was no significant difference in FT3 between NAFLD group and non-NAFLD group,suggesting that the pathophysiological condition of absolute or relative insufficient insulin secretion of T2DM will weaken the adjustment response of FT3 in obesity and lipid metabolism disorder,resulting in no increase of FT3 response and increasing the risk of NAFLD.（3）BMI and TG are independent risk factors for NAFLD in T2DM patients with normal thyroid function.Obesity and lipid metabolism disorder in patients with T2DM lead to the occurrence and development of NAFLD.</sup>