Lee Duk-Hee, Liu Ding Yong, Jacobs David R, Shin Hai-Rim, Song Kyungeun, Lee In-Kyu, Kim Bowan, Hider Robert C
Department of Preventive Medicine and Health Promotion Research Center, School of Medicine, Kyungpook National University, Daegu, Korea.
Diabetes Care. 2006 May;29(5):1090-5. doi: 10.2337/diacare.2951090.
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.
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).
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.
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.
最近，我们在一项前瞻性队列研究中报告，2型糖尿病补充维生素C的使用者心血管疾病死亡率增加。由于维生素C在存在具有氧化还原活性的铁时可能会引起氧化应激，我们推测非转铁蛋白结合铁（NTBI），一种易于发生氧化还原活性的铁形式，可能存在于2型糖尿病患者中。
我们使用高效液相色谱法测量了48例已知糖尿病患者（诊断后至少5年病程）、49例新诊断糖尿病患者和47例健康对照者（年龄和性别频率匹配）的血清NTBI水平。
NTBI在糖尿病患者中普遍存在：新诊断糖尿病患者中为59%，晚期糖尿病患者中为92%。三组之间的平均NTBI值差异显著，已知糖尿病患者的值最高，对照组最低（0.62±0.43 vs. 0.24±0.29 vs. 0.04±0.13微摩尔/升铁）。三组之间血清总铁或转铁蛋白饱和度百分比非常相似，但在已知糖尿病患者中，NTBI与血清总铁（r = 0.74，P < 0.01）和转铁蛋白饱和度百分比（r = 0.70，P < 0.01）密切相关。
与我们的假设一致，这些数据表明NTBI在2型糖尿病患者中普遍存在，且与疾病严重程度呈强梯度关系。需要进行前瞻性队列研究以阐明NTBI水平升高的临床相关性。
