A Correlation Study Between Non-alcoholic Fatty Liver Disease And Serum Triglyceride Level After Oral Fat Tolerance Test

Objective: By detecting serum triglyceride level after oral fat tolerance test(OFTT)in healthy volunteers and NAFLD patients,we analyzed the correlation between postprandial serum triglyceride level and the incidence of NAFLD.The clinical significance of change in postprandial lipid after oral fat tolerance test was further discussed.Methods: All subjects were recruited from Endocrinology Department of Hebei General Hospital.After written informed consent,physical examination and oral glucose tolerance test(OGTT)were carried out in all subjects.The subjects were selected according to the inclusion and exclusion criteria and those who met the inclusion criteria accepted the oral fat tolerance test.After a week of normal diet elution and 8-hours fasting,venous blood was collected in the morning,and then all subjects took a high-fat meal within 10 minutes.The high-fat meal was prepared by professional nutritionists,which provides 1500 kcal in total,and fat,protein and carbohydrate contents are 60%,20% and 20% respectively.Blood samples were collected 2 hours,4 hours,6 hours,8 hours and 10 hours after the high-fat meal.The other blood samples were stored in a refrigerator with temperature of-80 degrees.Diagnosis of non-alcoholic fatty liver disease(NAFLD)met the NAFLD diagnostic standard in 2018 guidelines for the diagnosis and treatment of non-alcoholic fatty liver disease.Ultrasound examinations in all patients were completed by a fixed technologist.Spss21.0 software was used for statistical analysis.Results: 1.There was no significant difference in gender between subjects in NAFLD group and in control group(P>0.05).BMI,waist circumference,systolic blood pressure and diastolic blood pressure of NAFLD group were higher than those in control group with statistical differences(P<0.01).FBG,FINS,TC,TG,LDL-C,Apo B,HOMA-IR of NAFLD group were higher than those in control group.Differences between the two groups was statistically significant(P<0.001).The levels of HDL-C,Apo A1 and Apo A1/Apo B in NAFLD group were statistically lower than those in control group(P<0.05).Parameters of subjects in NAFLD and control group were compared in different sex group.BMI,FBG,FINS and HOMA-IR in male and female NAFLD group were higher than those in control group,and the differences between groups were statistically significant(P<0.001).Fasting TC,TG and LDL-C in male and female NAFLD group were higher than those in control group,and HDL-C was lower than that in control group(P<0.05);2.According to fasting triglyceride level,all subjects were divided into two groups.BMI,FBG,FINS and HOMA-IR in hypertriglyceridemia group were higher than those with normal fasting triglyceride,and the difference between the two groups was statistically significant(P<0.001).Pearson chi square test was used to compare the incidence of NAFLD between the two groups,the incidence of NAFLD in hypertriglyceridemia group is higher than that in normal fasting triglyceride group,and the difference was statistically significant(P<0.001);3.TG in NAFLD group and Control group increased gradually after the oral fat tolerance test.In control group,TG level peaked at 4 hours after meal and decreased nearly back to fasting level after 10 hours.TG level of NAFLD subjects peaked at 6h postprandial,and did not fall back to the fasting level at 10 h postprandial;4.Risk factors of NAFLD were analyzed with Binary logistic regression analysis and a forest graph.The risk factors of NAFLD were BMI,TG 2h after meal,TG 4h postprandial,LDL-C and HOMA-IR;5.ROC curve of NAFLD was evaluated by TG level at different time point after oral fat tolerance test.Results showed that there was no significant difference(P>0.05)in evaluating NAFLD by TG at each time point after high-fat meal.The cut-off point of TG4 h was 2.65mmol/L;6.The postprandial TC,TG and LDL-C level of NAFLD group was higher than that in control group(P<0.001),while HDL-C level of NAFLD group was lower than that of control group(P<0.001).7.The peak time of TG after OFTT was 4 hours after meal and considering that the time of lipid metabolism is longer.Therefore,TG4h> 2.65mmol/L was regarded as the abnormal cut-off point of early evaluation of NAFLD All subjects were divided into three groups according to fasting and TG levels at 4 hours after OFTT: normal fat tolerance group(NFT),impaired fat tolerance group(IFT),and fasting hypertriglyceridemia group(FTHG).Among the three groups,age,BMI,WC,FBG,FINS,HOMA-IR,TC,TG,LDL-C all increased with the decrease of fat tolerance,while HDL-C decreased with the decrease of fat tolerance,and the differences in 3 groups were statistically significant(P<0.05).The incidence of NAFLD among 3 groups with different lipid tolerance was statistically significant(P<0.001).Oral fat tolerance test is very important for early detection of NAFLD.Conclusion:1.BMI,triglyceride level postprandial,LDL-C and HOMA-IR were risk factors of NAFLD.The risk of NAFLD increased with the increase of BMI and waist circumference and postprandial triglyceride level.2.The results of oral fat tolerance test showed that peak value of serum triglyceride in NAFLD patients after meal was higher than that in control group and the peak value of TG delayed in NAFLD patients.3.The definition of postprandial hypertriglyceridemia with TG4 h postprandial >2.65mmol/l is of clinical significance for the early evaluation of NAFLD.