Comparisons Of Serum Fibroblast Growth Factor-21 Levels Among The Different Glucose Tolerance Groups And Correlation With Multi-factors

Objective:To study the changes of serum fibroblast growth factor-21(FGF-21) in various glucose tolerance by measuring the serum FGF-21 concentrations among the subjects with normal tolerance(NGT) and with impaired glucose tolerance(IGT) and patients with type 2 diabetes mellitus(T2DM).Meanwhile to determine the relationships between the serum FGF-21 levels and factors including age,gender,body mass index(BMI),waist circumstance(WC),blood pressure,blood lipid,fasting plasma glucose(FPG),postprandial 2 hours plasma glucose(P2hPG),fasting insulin(FIN),homeostasis model assessment for insulin resistance(HOMA-IR),homeostasis model assessment for beta-cell secretion index(HOMA-IS).Contents:Forty-three patients with T2DM were recruited from the metabolic clinics at Tianjin Medical University General Hospital.Oral 75 gram glucose tolerance test was done among the volunteers.According to the results of the test,we chose thirty-five subjects with NGT and thirty-five cases with IGT randomly.Further,according to the HOMA-IR,the cases with IGT were divided into two subgroups.Namely subgroups with insulin resistance and without insulin resistance.Serum FGF-21 concentration was measured by enzyme linked immunosorbent assay(ELISA).Methods:All analysis were performed with SPSS 13.0 software package.Normal distribution of the data was tested using Kolmogorov-Smirnov nonparametric test.Serum FGF21 levels were log transformed in order to achieve a normal distribution of the data. Groups comparion were performed with one way analysis of variance(post Levene test).Comparion of any two groups among the groups were performed with SNK-q test.Analysis of covariance was used to compare data after adjustment for other variables.Pearson' correlation and stepwise multiple regression analysis were to determine the relationships between the serum FGF-21 level and multifactors. Difference were considered statistically significant at P≤0.05.Results:1.The serum FGF-21 level of T2DM was higher than in NGT and IGT groups.The results were 5.12±10.15pg/mk 40.99±10.99 p pg/mK 76.13±18.08pg/ml (P=0.000,p=0.000,respectively).The serum FGF-21 level was higher in cases with IGT than that in NGT subjects(P=0.023).The results were unchanged after adjustment for BMI.2.According to HOMA-IR,the cases with IGT were divided into two subgroups, namely IGT with insulin resistance and IGT without insulin resistance.There was difference among the serum FGF-21 level of NGT,subgroups of IGT without insulin resistance,subgroups of IGT with insulin resistance and T2DM. The results were respectively 35.12±pg/ml,38.07±8.95pg/ml,44.47±12.08pg/ml,76.13±18.08pg/ml.Among them,there was difference between the NGT subjects and cases of IGT without insulin resistance(P=0.742), the serum FGF-21 level of cases IGT with insulin resistance was higher than that in NGT subjects and cases of IGT without insulin resistance(P=0.006,P=0.046 respectively),the T2DM'serum FGF-21 level was higher than that in other three groups(P=0.000,P=0.000,P=0.000,respectively).3.There was difference in the serum FGF-21 level in the IGT and T2DM subgroups whose average age was no more than fifty years old(P=0.041, P=0.037,respectively),but there was no difference in the IGT and T2DM subgroups whose average age was more than fifty years old and no difference in the serum FGF-21 level between the males and females in the NGT subjects(all P＞0.05).4.Whatever NGT,IGT,T2DM,serum FGF-21 level always correlated positively with WC(r=0.557 P=0.001;r=0.872,P=0.000;r=0.627, P=0.000,respectively),and also correlated negatively with HDL-c(r=0.349,P=0.040;r=-0.521,P=0.001;r=-0.697,P=0.000,respectively) but there was no relationship between serum FGF-21 level and age,SBP,DBP,TC,TG,LDL-c,HDL-C,FPG,P2hPG(all P＞0.05).In IGT group, serum FGF-21 level also correlated positively with BMl(r=0.318,P=0.042).In the T2DM group,serum FGF-21 level negatively with HOMA-IS r=-0.198,=0.048).5.Stepwise multiple regression analysis showed that in NGT group,WC and HDL-c correlated independently with serum FGF-21 level,in IGT group,WC entered into regression equation but in T2DM group,WC and HDL-c were independently correlative factor with serum FGF-21 level.Conclusions:1.Serum FGF-21 level increased gradually with the worsening of the glucose tolerance.2.In cases with IGT,it was insulin resistance that resulted in serum FGF-21 level increased.3.In IGT and T2DM groups,serum FGF-21 level was lower in premenopause females than that in males who had similarly age.4.Whatever glucose tolerance,obesity always correlated positively with the serum FGF-21 level.In the NGT group,serum FGF-21 level also correlated negatively with HDL-c.In IGT group,serum FGF-21 level also correlated with fat distribution and insulin resistance.In T2DM patients,serum FGF-21 level also correlated positively with the average level of blood glucose,besides fat distribution and insulin resistance.5.In the NGT group,HDL-c and obesity correlated independently with serum FGF-21 level.In IGT group,only HOMA-IR affected serum FGF-21 level independently.In T2DM patients,HbAlCbmi and FIN independently affected the serum FGF-21 respectively.