title: Iron metabolism is associated with adipocyte insulin resistance and plasma adiponectin: the Cohort on Diabetes and Atherosclerosis Maastricht (CODAM) study.
abstract: OBJECTIVE
  Adipocyte insulin resistance (IR) is a key feature early in the pathogenesis of type 2 diabetes mellitus (T2DM), and although scarce, data in the literature suggest a direct role for iron and iron metabolism-related factors in adipose tissue function and metabolism. Serum ferritin and transferrin were shown to be associated with muscle insulin resistance (IR) and T2DM, but little is known about the role of iron metabolism on adipose tissue. We therefore investigated whether markers of iron metabolism were associated with adipocyte IR and plasma adiponectin.
  
  
  METHODS
  Serum ferritin, transferrin, total iron, non-transferrin-bound iron (NTBI), transferrin saturation, and plasma adiponectin were determined in 492 individuals. Adipocyte IR was defined by the product of fasting insulin and nonesterified fatty acids (NEFAs). Using linear regression analyses, we investigated the difference in adipocyte IR or adiponectin (in %) according to differences in iron metabolism markers.
  
  
  RESULTS
  Serum ferritin (β = 1.00% increase in adipocyte IR per 10 μg/L [95% CI 0.66-1.34]), transferrin (4.18% per 0.1 g/L [2.88-5.50]), total iron (1.36% per μmol/L [0.61-2.12]), and NTBI (5.14% per μmol/L [1.88-8.52]) were associated with adipocyte IR after adjustment for several covariates, including inflammatory markers. All markers of iron metabolism were also associated with NEFAs (all P < 0.01). In addition, ferritin and transferrin were inversely associated with adiponectin (both P < 0.01).
  
  
  CONCLUSIONS
  The observed associations of several markers of iron metabolism with adipocyte IR and adiponectin suggest that factors related to iron and iron metabolism may contribute to adipocyte IR early in the pathogenesis of T2DM.
authors.affiliation: Corresponding author: Nick Wlazlo, nickwlazlo@gmail.com.
authors.forename: Nick
authors.initials: N
authors.lastname: Wlazlo
authors.forename: Marleen M J
authors.initials: MM
authors.lastname: van Greevenbroek
authors.forename: Isabel
authors.initials: I
authors.lastname: Ferreira
authors.forename: Eugene H J M
authors.initials: EH
authors.lastname: Jansen
authors.forename: Edith J M
authors.initials: EJ
authors.lastname: Feskens
authors.forename: Carla J H
authors.initials: CJ
authors.lastname: van der Kallen
authors.forename: Casper G
authors.initials: CG
authors.lastname: Schalkwijk
authors.forename: Bert
authors.initials: B
authors.lastname: Bravenboer
authors.forename: Coen D A
authors.initials: CD
authors.lastname: Stehouwer
mesh_terms: D017667:Adipocytes / Q000378:metabolism; D052242:Adiponectin / Q000097:blood*; D000368:Aged; D003924:Diabetes Mellitus, Type 2 / Q000097:blood; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005293:Ferritins / Q000097:blood; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology*; D007501:Iron / Q000097:blood*; D008297:Male; D008875:Middle Aged
chemical_list: D052242:Adiponectin; D005230:Fatty Acids, Nonesterified; D005293:Ferritins; D007501:Iron