Study On The Correlation Between Serum Vitamin D Levels And Liver Fat Content In Type 2 Diabetes Mellitus

Objective:To investigate the relationship between serum 25-hydroxy vitamin D₃levels and liver fat content in patients with type 2 diabetes mellitus.Methods:In Autumn and winter season from 2015 to 2018,a total of 382 patients with type 2diabetes mellitus hospitalized in the department of endocrinology of the First Affiliated Hospital of Nanjing Medical University were recruited.According to whether being complicated with fatty liver or not diagnosed by ordinary B-ultrasound,they were divided into the group with fatty liver and without fatty liver.Anthropometrics,triglyceride（TG）,high density lipoprotein cholesterol（HDL-C）,and other indicators were measured.serum 25-hydroxy vitamin D₃ were detected by electrochemiluminescence.Traditional ultrasound was applied to detect whether they were NAFLD.141 patients from Nanjing areas who have used subcutaneous injection of insulin to control blood glucose for at least half a year,whose glycated hemoglobin level were less than 7.5%were selected.Moreover,Ultrasound images were captured using a scanner of ESAOTE S.p.A-Italia.The pictures with legible liver and renal were used to calculate liver fat content with software“NIH ImageJ”.The correlation between 25-hydroxyl vitamin D3 and liver fat content,BMI,waist circumference and HOMA-IR were analyzed by simple correlation analysis and partial correlation analysis.The relationship between 25-hydroxyl vitamin D3,HOMA-IR and liver fat content was analyzed by single factor ANOVA test.Results:（1）Compared to the group without fatty liver,25-hydroxyl vitamin D3 level of the group with fatty liver was significantly lower（P<0.05）.（2）Checking the influence factors of 25-hydroxyl vitamin D₃:age,course of disease,BMI,waist circumference and blood lipid level,we found that the level of serum 25-hydroxyl vitamin D₃ in T2DM patients was still negatively correlated with liver fat content（r=-0.272,P=0.005）.（3）Patients with T2DM were stratified according to liver fat content three division method.With the increase of liver fat content,the value of BMI,waist circumference,fasting insulin levels,HOMA-IR,TG and ALT increased and the level of 25-hydroxyl vitamin D₃ decreased（p<0.05）（Table 3）.（4）In patients with type 2 diabetes,serum 25-hydroxyl vitamin D₃ had a negative correlation with BMI（r=-0.283,P=0.001）,waist circumference（r=-0.263,P=0.002）,fasting insulin（r=-0.224,P=0.009）,HOMA-IR（r=-0.268,P=0.002）and liver fat content（r=-0.319,P=0.000）.After correction of the related factors,25-hydroxyl vitamin D₃ was negatively correlated with BMI,waist circumference,HOMA-IR,and fasting insulin（P<0.05）.Liver fat content was positively related with BMI（r=0.288,P=0.001）,waist circumference（r=0.313,P=0.000）,HOMA-IR（r=0.456,P=0.000）,fasting insulin（r=0.252,P=0.003）and ALT（r=0.199,P=0.02）.After correction of related factors,liver fat content was positively correlated with BMI,waist circumference,fasting insulin,HOMA-IR and ALT（P<0.05）,and negatively correlated with 25-hydroxyl vitamin D₃（r=-0.340,P=0.000）（Table 5,table 6）.（5）Among patients with type 2 diabetes,according to the quartile of HOMA-IR,the significantly negative correlation between 25-hydroxyl vitamin D₃ levels and liver fat content were found in stratification of the severest insulin resistance（r=-0.499,P=0.003）.After checking BMI and waistline,25-hydroxyl vitamin D₃ levels were still negatively correlated with liver fat content in stratification of the severest insulin resistance（r=-0.463,P=0.008）.Conclusion:Serum 25-hydroxyl vitamin D₃ levels were lower in type 2 diabetes patients with fatty liver than that of the group without fatty liver.Serum 25-hydroxyl vitamin D₃levels had a negative correlation with liver fat content in the severe insulin resistance.