Common Presence of Non–Transferrin-Bound Iron Among Patients With Type 2 Diabetes

  1. Duk-Hee Lee, MD1,
  2. Ding Yong Liu, PHD2,
  3. David R. Jacobs, Jr., PHD34,
  4. Hai-Rim Shin, MD5,
  5. Kyungeun Song, MD6,
  6. In-Kyu Lee, MD7,
  7. Bowan Kim, MD7 and
  8. Robert C. Hider, PHD2
  1. 1Department of Preventive Medicine and Health Promotion Research Center, School of Medicine, Kyungpook National University, Daegu, Korea
  2. 2Department of Pharmacy, King’s College London, London, U.K
  3. 3Department of Epidemiology, School of Public Health, University of Minnesota, Minnesota
  4. 4Department of Nutrition, University of Oslo, Oslo, Norway
  5. 5Division of Cancer Control and Epidemiology, National Cancer Center, Ilsan, Korea
  6. 6Department of Clinical Pathology, School of Medicine, Kyungpook National University, Daegu, Korea
  7. 7Department of Endocrinology, School of Medicine, Kyungpook National University, Daegu, Korea
  1. Address correspondence and reprint requests to Duk-Hee Lee, MD, Department of Preventive Medicine, School of Medicine, Kyungpook University, 101 Dongin-dong, Jung-gu, Daegu, Korea 700-422. E-mail: lee_dh{at}knu.ac.kr

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.

RESEARCH DESIGN AND 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 μmol/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.

Footnotes

  • A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.

  • The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

    • Accepted February 1, 2006.
    • Received December 16, 2005.
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  1. doi: 10.2337/dc05-2471 Diabetes Care May 2006 vol. 29 no. 5 1090-1095
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