The Association of Fat Metabolism and Diabetes Mellitus.docx

The Association of Fat Metabolism and Diabetes Mellitus.docx

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TheAssociationofFatMetabolismandDiabetesMellitus

TheAssociationofFatMetabolismandDiabetesMellitus

Instructor:

RobbieChan

Reportwrittenby:

ZhangXinwen

ID:

1131300048

BiochemistryandPhysiology

Signature

20May2013

TheAssociationofFatMetabolismandDiabetesMellitus

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