title: Plasma ceramides are elevated in obese subjects with type 2 diabetes and correlate with the severity of insulin resistance.
abstract: OBJECTIVE
  To quantitate plasma ceramide subspecies concentrations in obese subjects with type 2 diabetes and relate these plasma levels to the severity of insulin resistance. Ceramides are a putative mediator of insulin resistance and lipotoxicity, and accumulation of ceramides within tissues in obese and diabetic subjects has been well described.
  
  
  METHODS
  We analyzed fasting plasma ceramide subspecies by quantitative tandem mass spectrometry in 13 obese type 2 diabetic patients and 14 lean healthy control subjects. Results were related to insulin sensitivity measured with the hyperinsulinemic-euglycemic clamp technique and with plasma tumor necrosis factor-alpha (TNF-alpha) levels, a marker of inflammation. Ceramide species (C18:1, 18:0, 20:0, 24:1, and 24:0) were quantified using electrospray ionization tandem mass spectrometry after separation with high-performance liquid chromatography.
  
  
  RESULTS
  Insulin sensitivity (mg x kg(-1) x min(-1)) was lower in type 2 diabetic patients (4.90 +/- 0.3) versus control subjects (9.6 +/- 0.4) (P < 0.0001). Type 2 diabetic subjects had higher (P < 0.05) concentrations of C18:0, C20:0, C24:1, and total ceramide. Insulin sensitivity was inversely correlated with C18:0, C20:0, C24:1, C24:0, and total ceramide (all P < 0.01). Plasma TNF-alpha concentration was increased (P < 0.05) in type 2 diabetic subjects and correlated with increased C18:1 and C18:0 ceramide subspecies.
  
  
  CONCLUSIONS
  Plasma ceramide levels are elevated in type 2 diabetic subjects and may contribute to insulin resistance through activation of inflammatory mediators, such as TNF-alpha.
authors.affiliation: Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA.
authors.forename: Jacob M
authors.initials: JM
authors.lastname: Haus
authors.forename: Sangeeta R
authors.initials: SR
authors.lastname: Kashyap
authors.forename: Takhar
authors.initials: T
authors.lastname: Kasumov
authors.forename: Renliang
authors.initials: R
authors.lastname: Zhang
authors.forename: Karen R
authors.initials: KR
authors.lastname: Kelly
authors.forename: Ralph A
authors.initials: RA
authors.lastname: Defronzo
authors.forename: John P
authors.initials: JP
authors.lastname: Kirwan
mesh_terms: D000328:Adult; D002518:Ceramides / Q000097:blood* / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood* / Q000503:physiopathology; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
chemical_list: D002518:Ceramides; D014409:Tumor Necrosis Factor-alpha