title: Fatty Acids, Obesity and Insulin Resistance.
abstract: OBJECTIVE
  Although elevated free fatty acid (FFA) levels in obesity have been considered to be of importance for insulin resistance, a recent meta-analysis suggested normal FFA levels in obese subjects. We investigated fasting circulating FFA and glycerol levels in a large cohort of non-obese and obese subjects.
  
  
  METHODS
  Subjects recruited for a study on obesity genetics were investigated in the morning after an overnight fast (n = 3,888). Serum FFA (n = 3,306), plasma glycerol (n = 3,776), and insulin sensitivity index (HOMA-IR,n = 3,469) were determined. Obesity was defined as BMI ≥ 30 kg/m 2 and insulin resistance as HOMA-IR ≥ 2.21.
  
  
  RESULTS
  In obese subjects, circulating FFA and glycerol levels were higher than in non-obese individuals (by 26% and 47%, respectively; both p < 0.0001). Similar results were obtained if only men, women or medication-free subjects were investigated. Insulin resistance and type 2 diabetes were associated with a further minor increase in FFA/glycerol among obese subjects. When comparing insulin-sensitive non-obese with insulin-sensitive or -resistant obese individuals, FFA and glycerol were 21–29% and 43–49% higher in obese individuals, respectively.
  
  
  CONCLUSIONS
  Circulating FFA and glycerol levels are markedly elevated in obesity but only marginally influenced by insulin resistance and type 2 diabetes. Whether these differences persist during diurnal variations in circulating FFA/glycerol, remains to be established
authors.forename: Peter
authors.initials: P
authors.lastname: Arner
authors.forename: Mikael
authors.initials: M
authors.lastname: Rydén
mesh_terms: D000328:Adult; D003924:Diabetes Mellitus, Type 2 / Q000097:blood*; D005227:Fatty Acids / Q000097:blood; D005230:Fatty Acids, Nonesterified / Q000097:blood*; D005260:Female; D005990:Glycerol / Q000097:blood; D006801:Humans; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood*; D055815:Young Adult
chemical_list: D005227:Fatty Acids; D005230:Fatty Acids, Nonesterified; D007328:Insulin; D005990:Glycerol