Common presence of non-transferrin-bound iron among patients with type 2 diabetes.
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.
Lee
Duk-Hee
DH
Department of Preventive Medicine and Health Promotion Research Center, School of Medicine, Kyungpook National University, Daegu, Korea. lee_dh@knu.ac.kr
Liu
Ding Yong
DY
Jacobs
David R
DR
Shin
Hai-Rim
HR
Song
Kyungeun
K
Lee
In-Kyu
IK
Kim
Bowan
B
Hider
Robert C
RC
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*
D014168:Transferrin; D002097:C-Reactive Protein; D005293:Ferritins; D007501:Iron