title: Common presence of non-transferrin-bound iron among patients with type 2 diabetes.
abstract: OBJECTIVE
  Recently, we reported increased cardiovascular disease mortality among supplemental vitamin C users with type 2 diabetes in a prospective cohort study. Because vitamin C may cause oxidative stress in the presence of redox active iron, we hypothesized that non-transferrin-bound iron (NTBI), a form of iron susceptible to redox activity, may be present in patients with type 2 diabetes.
  
  
  METHODS
  We measured serum NTBI levels using high-performance liquid chromatography in 48 patients with known diabetes (at least 5 years duration since diagnosis), 49 patients with newly diagnosed diabetes, and 47 healthy control subjects (frequency matched on age and sex).
  
  
  RESULTS
  NTBI was commonly present in diabetes: 59% in newly diagnosed diabetes and 92% in advanced diabetes. Mean NTBI values varied significantly between the three groups, with the highest values being observed in patients with known diabetes and the lowest in the control subjects (0.62 +/- 0.43 vs. 0.24 +/- 0.29 vs. 0.04 +/- 0.13 micromol/l Fe). Serum total iron or percent transferrin saturation were very similar among the three groups, yet NTBI was strongly associated with serum total iron (r = 0.74, P < 0.01) and percent transferrin saturation (r = 0.70, P < 0.01) among the patients with known diabetes.
  
  
  CONCLUSIONS
  Consistent with our hypothesis, these data demonstrate the common existence of NTBI in type 2 diabetic patients with a strong gradient with severity. Prospective cohort studies are required to clarify the clinical relevance of increased NTBI levels.
authors.affiliation: Department of Preventive Medicine and Health Promotion Research Center, School of Medicine, Kyungpook National University, Daegu, Korea. lee_dh@knu.ac.kr
authors.forename: Duk-Hee
authors.initials: DH
authors.lastname: Lee
authors.forename: Ding Yong
authors.initials: DY
authors.lastname: Liu
authors.forename: David R
authors.initials: DR
authors.lastname: Jacobs
authors.forename: Hai-Rim
authors.initials: HR
authors.lastname: Shin
authors.forename: Kyungeun
authors.initials: K
authors.lastname: Song
authors.forename: In-Kyu
authors.initials: IK
authors.lastname: Lee
authors.forename: Bowan
authors.initials: B
authors.lastname: Kim
authors.forename: Robert C
authors.initials: RC
authors.lastname: Hider
mesh_terms: D002097:C-Reactive Protein / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000097:blood*; D005260:Female; D005293:Ferritins / Q000097:blood; D006801:Humans; D007501:Iron / Q000097:blood*; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D014168:Transferrin / Q000378:metabolism*
chemical_list: D014168:Transferrin; D002097:C-Reactive Protein; D005293:Ferritins; D007501:Iron