The Association of Fat Metabolism and Diabetes Mellitus文档格式.docx
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Instructor:
RobbieChan
Reportwrittenby:
ZhangXinwen
ID:
1131300048
BiochemistryandPhysiology
Signature
20May2013
Abstract
DiabetesMellitusisanendocrine-metabolicsyndrome;
itsmajorfeaturesarehyperglycemiaandhighurinesugarlevel.AccordingtothesituationofinsulindependencecanbeclassifiedastypeIdiabetes(T1DM)andtypeⅡdiabetes(T2DM).Abnormalfat(lipid)metabolismexistedinboththesetwotypesofdiabetes.ForTypeIdiabetespatients,theirbloodleveloftriglycerides(TG)ishighbeforetreatments.Insulincansuppresstheactivityoflipase.T1DMpatientslackinsulinintheirblood,sotheirlipasewillincreaseandactiveinbloodlevel.Thus,abigamountoffreefattyacid(FFA)andbigamountofglucoseinbloodwillprovideadequatematerialsforthelivertosynthesisthevery–lowdensitylipoprotein(VLDL).ForT2DMpatients,thebackgroundandcauseofthediseasecanbegeneticfactororenvironmentalfactororboth.Thus,duringthesubclinicalstage,theT2DMpatientsalreadyhavedyslipidemia,increasedTUandVLDLintheirbloodlevel,lowerhighdensitylipoproteincholesterol(HDL-C)inbloodlevelandincreasedamountofsmalldensitylowdensitylipoprotein(SLDL).
Introduction
Severalthousandyearsago,manycountriesintheworldalreadyfoundthesweeturinedisease,butitsnamed“DiabetesMellitus”wasinthe17thcentury.Thisdiseaseisassociatedwithfatpeople,butthepathogenesiswasfoundaftermanyyears.Diabetesmellitusisadisorderofglucosemetabolism.Diabetescanbecausedbythelackofinsulinorlackofresponsetoinsulin,whichresultsinglucoseelevation.Glucoseisthemostreadilyavailableenergysourceforthebody.Whenglucosecan'
tbeusedduetoaproblemwithinsulin,proteinsandfatsareusedasalternativeenergysources.Therearetwomaintypesofdiabetes:
diabetesmellitusType1andType2.DiabetesmellitusType1iscausedbythedestructionofcellsthatproduceinsulinbytheimmunesystem.Thisresultsinlackofinsulinproduction.DiabetesmellitusType1iscommonlyseeninyounger,non-obesepeople.DiabetesmellitusType2iscausedbythebody'
sresistancetoinsulinduetoabnormaldietingthatresultinchronicelevationsofglucose.Whenglucoseishighintheblood,insulinishighaswell.Whenthishappensovertime,thebodybecomesdesensitizedtoinsulin.DiabetesmellitusType2iscommonlyseeninolder,overweightpeople.(Joy,2011)
Inthelastdecade,therehasseenashiftfromthetraditional'
glucocentric'
viewofthesyndromeassociatedwithinsulinresistancetoanincreasinglyacknowledged'
lipocentric'
viewpoint.Theconceptisthatlipidsmayactassignalingfactorsthatregulatemetabolicfunctionsintargettissues.Itwasfirstsuggestedmorethan40yearsago.(Roberto,2012)
Theabnormalfat(lipid)metabolismtheoryandstudyofdiabeteshadbigsuccessinthelastcentury.In1960,RoseK.L.WongandJ.T.VanBruggenusedthediabeticrattostudylipidmetabolismandmadeimportantadvancesontheassociationoffatmetabolismanddiabetesmellitus.Theirinvestigationsweredesignedtocomparethelipidmetabolismofdiabeticratswiththatofcontrolsandtofurthercomparethelipidmetabolismofalloxanandpancreatectomizeddiabeticanimals.Theconversionoftracerdosesofacetate-l-Cl4tofattyacidandcholesterolwasdeterminedincarcass,skin,gut,andlivertissuesafterasingleinjectionoftracer.Determinationsofserumcholesterolweremadeandtheradioactivityoftheserumcholesterolwasalsostudiedonanumberoftheanimals.(Wong&
Bruggen,1960)
TypeIDiabetes(T1DM)
Currently,T1DMisusuallyaccompaniedwithdyslipidemia,whichrelatedwithinsulin-dependentstepsoftheintravascularlipoproteinmetabolism.T1DMdyslipidemiamaypredisposetoprecociouscardiovasculardiseaseandthelipidstatusinT1DMunderintensiveinsulintreatmenthasnotbeensufficientlyexplored.Thestudywasaimtoinvestigatetheplasmalipidsamountandquality.Atthesametime,themetabolismofLDLandHDLininsulin-treatedT1DMpatientswithhighglycemiclevelswillbemonitored.(Feitosa,2013)
Afterseveralexperimentandmeasurement,theyfoundoutthatT1DMpatientsunderintensiveinsulintreatmentbutwithpoorglycemiccontrolhadlowerLDL-cholesterolwithhigherLDEplasmaclearance,indicatingthatLDLplasmaremovalwasevenmoreefficientthanincontrols.Furthermore,HDL-cholesterolandtriglycerides,cholesterolesterificationandtransferoflipidstoHDL,animportantstepinreversecholesteroltransport,wereallnormal.Coexistenceofhighglycemialevelswithnormalintravascularlipidmetabolismmayberelatedtodifference