Dissertation
Dissertation > Medicine, health > Internal Medicine > Endocrine diseases and metabolic diseases > Islet disease > Diabetes

Effect of Meals with Different Nutrient Contents on Incretin and Islet Function in Healthy Subjects

Author GaoZhe
Tutor SongGuangYao
School Hebei Medical University
Course Internal Medicine
Keywords Meal composition glucagon-like peptide-1 gastric inhibitory polypeptide Carbohydrate Protein saturated fat acid monounsaturated fat acid
CLC R587.1
Type Master's thesis
Year 2010
Downloads 35
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Objective:To explore the effect of meals with different nutrient contents on incretin and islet function in healthy subjects.Methods:The experiment used a randomized block design. Before each test,15 healthy subjects received a 1-week pre-experiment eucaloric diet,consisting of 55% CHO,30% fat and 15% protein.In a randomized order each of the 15 subjects consumed within 5 min the four isocaloric(300kcal) and isovolemic(300ml) meals containing different macronutrient compositions, including high carbohydrate(HC; 60% CHO,20% protein,20% fat),high protein (HP;20% CHO,60% protein,20% fat),high saturated fat acid (HSF;20% CHO,20% protein,60% fat provided by lard oil) and high monounsaturated fat acid (HMF;20% CHO,20% protein,60% fat provided by tea oil),on four separate occasions with a minimum 1-week washout among meals. After fasting for 12h an intravenous catheter was inserted into an antecubital vein at 7:00 a.m.Blood samples were collected immediately before (time 0) and at 30,60,120,180 and 240 min following meal intake, and plasma concentrations of gastric inhibitory polypeptide(GIP), glucagon-like peptide-1(GLP-1) and serum concentrations of glucose, insulin, triglyceride(TG) and free fatty acid (FFA) were measured.Results:1. We found no significant difference in fasting concentrations of glucose,insulin,triacylglycerol,FFA,GIP and GLP-1 among the different meals (P>0.05).2.Analysis of the areas under the curve of glucose,inslulin,triglyceride, FFA,GIP and GLP-1.2.1Postprandia glucose did not increase significantly following HP, HSF and HMF meals (P>0.05). Compared with the other meals, significant increase in AUCglu30min and AUCglu240min was found following HC meal (P<0.05).2.2The increased postprandial insulin concentrations were seen following four meals.Comparing with the other meals, significant increase in AUCins30min and AUCins240min was observed following HC meal (P<0.01 and P<0.05).AUCins30min was significantly higher following HP meal as compared with HMF and HSF meals (P<0.05). AUCins240min was found to be significantly higher following HSF meal as compared with HMF meal (P<0.01).2.3Compared with HC and HP meals, significant increase in AUCTG30min and AUCTG240min was found following HMF and HSF meals (P<0.05); AUCTG30min and AUCTG240min were significantly higher following HSF meal as compared with HMF meal (P<0.05);AUCTG30min and AUCTG240min were higher following HC meal as compared with HP meal with no significant difference (P>0.05).2.4We found no significant difference in AUCFFA30min among the different meals (P>0.05).Comparing HC and HP meals,a significant increase in AUCFFA240min was observed following HMF and HSF meals (P<0.05);AUCFFA240min was found to be higher following HC meal compared with HP meal with no significant difference (P>0.05);AUCFFA240min was significantly higher following HSF meal as compared with HMF meal (P<0.05).2.5We found significant differences in AUCGIP30min among the different meals(P<0.05),AUCGIP30min was highest in HC groups, followed with HP group, HMF group and HSF group in order. Comparing with the other meals,a significant increase in AUCGIP240min was observed following HC meal (P<0.01);Compared with HMF and HSF meals, no significant difference was observed in AUCGIP240min following HP meal (P>0.05);Compared with HSF meal,a significant increase in AUCGIP240min was found following HMF meal (P<0.01).2.6Comparing with the other meals, significant increase in AUCGLP-1 30min and AUCGLP-1 240min was found following HC meal (P<0.01);Compared with HMF and HSF meals, there were no significant difference in AUCGLP-1 30min and AUCGLP-1 240min following HP meal (P>0.05);Compared with HSF meal, significant increase in AUCGLP-1 30min and AUCGLP-1 240min was found following HMF meal (P<0.05 and P<0.01).3. Additionally, the empirical indexes of postprandialβcell function were assessed.3.1Compared with the other meals, a significant increase in △I30/△G30 was found following HP meal (P<0.05);and no significant difference was observed in△I30/△G30 following HC,HSM and HMF meals (P>0.05).3.2Compared with HMF and HSF meals,a significant increase in AUCI/AUCG was found following HC and HP meals (P<0.01);no significant difference was observed in AUCI/AUCG following HC and HP meals (PP>0.05);AUCI/AUCG was significantly higher following HSF meal as compared with HMF meal (P<0.01).4. Correlations among variables. By Pearson’s correlation analysis, we observed significant correlations between AUCins30min and AUCGIP30min (r=0.476,P<0.05),between AUCins30min and AUCGLP-1 30min (r=0.535,P<0.05) in HC group whereas not in HF and HP groups.AUCGLP-1 30min is correlated to AUCglu30min(r=0.517,P<0.05),wheras AUCGIP30min is not (r=0.346,P=0.056). A significantly correlation of AUCins30min with AUCGIP30min (r=0.433,P<0.05),but not with AUCGLP-1 30min (P>0.05),was also noted in HP group.No such correlations were seen for AUCins30min, AUCGIP30min or AUCGLP-1 30min following HSF and HMF meal (P>0.05).Conclusion:1.In conclusion, this study demonstrates that circulating GIP,GLP-1 andβcell function are affected by the nutrient composition of the meal in healthy adults.2.HC meal may stimulate GIP,GLP-1 and insulin secretion to a higher extent than the other meals.3.HP meal promotes postprandial elevations in GIP,insulin and indexes of postprandialβcell function during the early stage postprandially.4.HMF meal promotes postprandial increases in GIP and GLP-1 as compared with HSF meal, while HSF meal induces significant increase in insulin.

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