Oxidative stress, antioxidant status and DNA damage in patients with impaired glucose regulation and newly diagnosed Type 2 diabetes.
Previous studies have postulated the association between oxidative stress and Type 2 diabetes. Considering the long pre-diabetic period with IGR (impaired glucose regulation) and its high risk of developing diabetes, to test this hypothesis, we have investigated oxidative stress pathways and DNA damage in patients with IGR and newly diagnosed Type 2 diabetes. The study population consisted of 92 subjects with NGT (normal glucose tolerance), 78 patients with IGR and 113 patients with newly diagnosed diabetes. Plasma MDA (malondialdehyde) and TAC (total antioxidative capacity) status, erythrocyte GSH content and SOD (superoxide dismutase) activity were determined. A comet assay was employed to evaluate DNA damage. Compared with subjects with NGT, patients with IGR had reduced erythrocyte SOD activity. Patients with diabetes had a higher plasma MDA concentration, but a lower plasma TAC level and erythrocyte SOD activity, than the NGT group. Correlation analysis revealed a strong positive association between IR (insulin resistance) and MDA concentration, but negative correlations with TAC status and SOD activity. With respect to beta-cell function, a positive association with TAC status and an inverse correlation with GSH respectively, were observed. The comet assay revealed slight DNA damage in patients with IGR, which was increased in patients with diabetes. Significant correlations were observed between DNA damage and hyperglycaemia, IR and beta-cell dysfunction. In conclusion, the results of the present study suggest that hyperglycaemia in an IGR state caused the predominance of oxidative stress over antioxidative defence systems, leading to oxidative DNA damage, which possibly contributed to pancreatic beta-cell dysfunction, IR and more pronounced hyperglycaemia. This vicious circle finally induced the deterioration to diabetes.
Song
Fangfang
F
Department of Nutrition and Food Hygiene, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China.
Jia
Wenbo
W
Yao
Ying
Y
Hu
Yafei
Y
Lei
Lin
L
Lin
Jie
J
Sun
Xiufa
X
Liu
Liegang
L
D000975:Antioxidants / Q000378:metabolism*; D004247:DNA / Q000032:analysis; D004249:DNA Damage / Q000235:genetics*; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology / Q000235:genetics / Q000378:metabolism*; D004912:Erythrocytes / Q000201:enzymology; D005260:Female; D005947:Glucose / Q000378:metabolism; D018149:Glucose Intolerance / Q000235:genetics / Q000378:metabolism*; D005978:Glutathione / Q000097:blood; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D007333:Insulin Resistance / Q000502:physiology; D008297:Male; D008315:Malondialdehyde / Q000097:blood; D008875:Middle Aged; D018384:Oxidative Stress / Q000502:physiology*; D013482:Superoxide Dismutase / Q000097:blood
D000975:Antioxidants; D004247:DNA; D005947:Glucose; D005978:Glutathione; D006442:Glycated Hemoglobin; D008315:Malondialdehyde; D013482:Superoxide Dismutase