Serum oxidized low density lipoprotein, paraoxonase 1 and lipid peroxidation levels during oral glucose tolerance test.
Increasing evidence suggests that the postprandial state is a contributing factor to the development of atherosclerosis. To evaluate the effects of acute hyperglycemia on the oxidative stress, concentrations of serum-oxidized low density lipoprotein (oxLDL), paraoxonase 1 (PON1), and thiobarbituric acid reactive substances (TBARS) were measured in subjects with normal glucose tolerance (NGT) (n=35), impaired glucose tolerance (IGT) (n=25), and diabetic glucose tolerance (DGT) (n=20). In NGT group, the 2 hours' TBARS and oxLDL levels were not statistically different when compared to baseline, and 2 hours' PON1 activities were higher when compared to baseline (p<0.01). Subjects with IGT and DGT have higher 2 hours' serum TBARS and oxLDL levels than their baseline levels (p<0.01, for each). Baseline oxLDL levels of both IGT and DGT groups were higher than NGT group (p<0.01 and p<0.01, respectively). While there were not any significant differences in 2 hours' versus baseline PON1 activities in the IGT group, the 2 hours' versus baseline PON1 activities in the DGT group were significantly lower (p<0.01). The postchallenge 2 hours' PON1 activities of both IGT and DGT groups were lower than NGT group (p<0.01 and p<0.01, respectively). Baseline oxLDL was positively correlated with 2 hours' glucose (r=0.613, p<0.01) in IGT and DGT groups. PON1 activities were correlated with HDL-cholesterol, total cholesterol, and fasting glucose (r=0.680, r=0.698 and r=0.431, respectively, for each p<0.01) in NGT. In conclusion, oxidative stress occurs at an early stage in diabetes, and protective effects of HDL against atherosclerosis may be dependent on the PON1 activities.
Serin
O
O
Taksim Education and Research Hospital, and Istanbul University, Cerrahpasa Faculty of Medicine, Department of Biochemistry, Istanbul, Turkey.
Konukoglu
D
D
Firtina
S
S
Mavis
O
O
D000284:Administration, Oral; D043303:Aryldialkylphosphatase / Q000097:blood*; D003710:Demography; D005951:Glucose Tolerance Test; D006801:Humans; D015227:Lipid Peroxidation; D008077:Lipoproteins, LDL / Q000097:blood*; D008875:Middle Aged; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis
D008077:Lipoproteins, LDL; D017392:Thiobarbituric Acid Reactive Substances; C099252:oxidized low density lipoprotein; D043303:Aryldialkylphosphatase