Impact of glucose excursion and mean glucose concentration in oral glucose-tolerance test on oxidative stress among Japanese Americans

Shuhei Nakanishi, Masayasu Yoneda, Shusaku Maeda Department of Molecular and Internal Medicine, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan Aim: To evaluate the impact of glucose excursion (GE) and mean glucose concentration (MGC) on oxidative stress among persons with or without diabetes. Materials and methods: We examined 775 Japanese Americans who had normal glucose tolerance (NGT), impaired glucose tolerance, or diabetes according to the 75 g oral glucose-tolerance test, using fasting, 1-hour, and 2-hour glucose data. We calculated GE by subtracting the minimum from the maximum glucose level among three points and calculated MGC using these measurements. We investigated the relationship between GE or MGC and urinary isoprostane as a marker of oxidative stress. Results: According to tertiles of GE or MGC, GE was associated with isoprostane levels among subjects with NGT as well as those with diabetes (P=0.004 and 0.033 for trend, respectively). However, MGC was associated with isoprostane only among NGT subjects (P=0.001 for trend). Association between GE and isoprostane was significant when adjustment was made for age, sex, smoking status, body mass index, C-reactive protein, glucose tolerance status, and homeostatic model assessment (P=0.029), but the association with MGC was not significant. Conclusion: Our results suggest the possibility that GE might result in oxidative stress, and the relationship is stronger than that for MGC. Keywords: glucose excursion, glucose-tolerance test, oxidative stress