Levels Of Pancreatic Polypeptide And Its Affecting Factors In Subjects With Different Glucose Tolerance And Body Mass Index

Objective:The purpose of this study is to compare the concentrations of serum pancreatic polypeptide(PP),insulin(INS),C-peptide(C-P),and glucagon(GC)in different glucose tolerance and body mass index(BMI)stages,analyze the influencing factors of PP secretion,and further explore the PP action in the pathogenesis of obesity and diabetes.Methods:Data were collected from 100 subjects who attended the Endocrinology clinic and physical examination center of Affiliated Hospital of Medical College Qingdao University between June 2019 and December 2019.OGTT was carried out to all subjects after fasting for 8～12 hours.According to the result of OGTT,subjects were divided into normal glucose tolerance(NGT)group,impaired glucose regulation[IGR,including impaired fasting glucose(IFG)and impaired glucose tolerance(IGT)]group,and newly diagnosed type 2 diabetes mellitus(T2DM)group.Data were also collected from 85 T2DM patients who were hospitalized in the Endocrinology and Metabolism Department of Affiliated Hospital of Medical College Qingdao University between January 2020 and June 2020.Individuals were divided into three groups according to their BMI:normal BMI group,overweight group and obesity group.Steamed bread meal test(SBMT)was carried out to all T2DM patients after fasting.Clinical data including age,sex,height,weight,waist circumstances,systolic blood pressure,diastolic blood pressure,history of illness and drugs intake were collected.The concentrations of fasting blood glucose(FBG),lipids[triglycerides(TG),cholesterol(TC),low-density lipoprotein-cholesterol(LDL-c),high-density lipoprotein-cholesterol(HDL-c),free fatty acids(FFA)],hepatic function[Alanine aminotransferase(ALT),aspartate aminotransferase(AST),y-glutamyl transpeptadase(GGT)],renal function[creatinine(Cr),urea nitrogen(BUN),uric acid(UA)]and glycosylated hemoglobin(HbAlc)were detected.Blood samples at 0,60min and 120min were collected,and the concentrations of blood glucose,PP,GC,insulin(INS)and C-peptide(C-P)of each sample were measured.The area under the curve(AUC)of PP,GC,INS and C-P after OGTT or SBMT were calculated.Results:1 Comparation among different glucose tolerance state:Fasting and postprandial PP in the group of IGR and newly diagnosed T2DM were higher than those in NGT group.The differences were statistically significant in 60min after OGTT(P=0.036),while no significant difference was detected between groups in fasting or 120min after OGTT(P>0.05).AUCpp was significantly higher in the IGR and newly diagnosed T2DM group than in the NGT group(P=0.047,P=0.031),while no significant difference was detected between T2DM and IGR group(P>0.05).2 Comparation among different BMI groups in T2DMs:Fasting PP was insignificantly different among different BMI groups(P>0.05);In 60min and 120min after SBMT,PP concentrations in overweight and obesity were significantly lower than that of normal BMI group(P<0.05).AUCpp in overweight and obesity were significantly lower than that in the normal BMI group(P=0.013,P=0.002).3 Factors influencing PP secretion in T2DM patients:(1)Correlation analysis showed that fasting PP was positively correlated with AUCgc;In 60min after SBMT,PP was negatively correlated with BMI,HbA1c、LDL-c and TC,and positively correlated with AUCcp and AUCgc;In 120min after SBMT,PP was negatively correlated with BMI,and positively correlated with AUCgc(all P<0.05).(2)Multiple linear stepwise regression:Use AUCpp as the dependent variable and potentially correlated factors as the independent variables for stepwise fitting.Results indicated that the influence of BMI and AUCgc on AUCpp were statistically significant(P<0.05),and the regression equation is AUCpp=1385.205-0.630×BMI+0.724×AUCgc。Conclusions:1 Compared with NGT subjects,IGR and T2DM patients have an enhanced postprandial PP secretion,which tends to be more significant in IGR subjects.2 Overweight and obesity appear to be associated with an impaired postprandial PP response.This response could be masked by the abnormalities under glucose tolerance.3 In T2DMs,the secretion of PP is mainly affected by BMI and GC.There may exist a potential protective effect of PP on the function of islet cells.