title: Effects of insulin sensitivity, body composition, and fitness on lipoprotein particle sizes and concentrations determined by nuclear magnetic resonance.
abstract: BACKGROUND
  Insulin resistance has been reported to be associated with development of atherogenic dyslipidemia. However, the confounding effects that obesity and low levels of cardiorespiratory fitness have on the relationship between insulin resistance and the development of atherogenic dyslipidemia remain to be adequately addressed.
  
  
  OBJECTIVE
  This study sought to examine the independent and combined effects of insulin sensitivity, body composition, and cardiorespiratory fitness on lipoprotein particle sizes and concentrations.
  
  
  METHODS
  Eight-four healthy, nondiabetic men (n = 43) and women (n = 41) were studied. The participants had a wide range of ages (18-30 and 65-80 yr), body composition (7.2-52.8% fat), and cardiorespiratory fitness (VO(2) peak, 13.5-66.2 ml/kg · min). Body composition, cardiorespiratory fitness, insulin sensitivity, and lipoprotein particle profiles were assessed using dual-energy x-ray absorptiometry, cardiopulmonary exercise testing, a hyperinsulinemic-euglycemic clamp, and nuclear magnetic resonance spectroscopy, respectively.
  
  
  RESULTS
  Low levels of insulin sensitivity and cardiorespiratory fitness and higher levels of adiposity were associated with the accumulation of small, dense, low-density lipoprotein particles; small high-density lipoprotein particles; triglycerides; and very low-density lipoprotein particles. Multivariate forward-stepwise regression revealed that higher levels of adiposity, in particular truncal fat, were the strongest predictor of the lipoprotein particle size and concentration data, followed by insulin sensitivity.
  
  
  CONCLUSIONS
  As expected, the accumulation of atherogenic lipoprotein particles (e.g. small, dense, low-density lipoprotein particles and small, high-density lipoprotein particles) was associated with low levels of insulin sensitivity, cardiorespiratory fitness, and higher levels of adiposity. However, multivariate forward-stepwise regression revealed that triglycerides, followed by truncal fat mass, were the strongest predictors of the lipoprotein particle size and concentration data.
authors.affiliation: Division of Endocrinology, Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota 55905, USA. irving.brian@mayo.edu
authors.forename: Brian A
authors.initials: BA
authors.lastname: Irving
authors.forename: K Sreekumaran
authors.initials: KS
authors.lastname: Nair
authors.forename: Manivannan
authors.initials: M
authors.lastname: Srinivasan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001823:Body Composition / Q000502:physiology*; D005260:Female; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D008074:Lipoproteins / Q000032:analysis* / Q000097:blood / Q000737:chemistry; D008297:Male; D008875:Middle Aged; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D009994:Osmolar Concentration; D010316:Particle Size; D010809:Physical Fitness / Q000502:physiology*; D055815:Young Adult
chemical_list: D008074:Lipoproteins