| ObjectiveTo investigate the serum 8-hydroxy-2'-deoxyguanosine (8-OHdG) level in cases with different glucose metabolism and evaluate DNA oxidative injury in different stages of glucose metabolism as well as the relevance of insulin resistance,β-cell function and 8-OHdG.It helps to understand the pathophysi- ology of the different stages of the glucose metabolism and provide the objective basis and a new way for prevention and treatment of type 2 diabetes mellitus(T2DM).Method156 patients(male 80,female 76),enrolled from Medical Examination Center of Qingdao Municipal Hospital, underwent OGTT and insulin release test and were classified into normal glucose tolerance(NGT),impaired fasting glucose(IFG),isolated impaired glucose tolerance(IGT),IFG with IGT(IFG+IGT) and type 2 diabetes mellitus(T2DM) groups based on OGTT results.The level of body mass index (BMI),blood pressure, fasting plasma glucose (FPG), fasting insulin (FINS), cholesterol (CHO), triglyceride (TG), low density lipoprotein (LDL-C), high density lipoprotein (HDL-C), glycosylated hemoglobin (HbA1c) and uric acid (UA) were measured at fasting time.With insulin resistance index (HOMA-IR) to assess insulin resistance, andβ-cell function index (HOMA-β) to assess the basal insulin secretion,with the 30-minute incremental ratio of insulin to glucose (ΔI30/ΔG30) to assess early stage of insulin secretion, insulin area under the curve (AUCI) to assess insulin secretion after glucose load.By enzyme-linked immunosorbent assay (ELISA) method to measure the serum 8-OHdG level in different glucose metabolism groups.Results①There was no significant statistical difference in age,sex,systolic blood pressure (SBP),diastolic blood pressure (DBP) and UA among groups of NGT,IFG,IGT,IFG+IGT and T2DM(P>0.05).Compared to NGT, the level of BMI,TG,CHO,LDL-C were higher and HDL-C was lower in IFG,IGT,IFG+IGT and T2DM.②The serum 8-OHdG level inceased from NGT,IFG,IGT,IFG+IGT to T2DM.Compared to NGT,there is statistical difference in the other groups(P<0.05).There was no statistical differenc among the IFG,IGT and IFG+IGT(P>0.05).There was no statistical differenc between IFG+IGT and T2DM(P >0.05).③Compared to NGT group,HOMA-IR was increased by 27%,11%,65% and 77% respectively in IFG,IGT,IFG+IGT and T2DM groups.④Compared to NGT group after adjused by HOMA-IR,the level of HOMA-βwas decreased by 34%,44%,53% and 83% respectively in IFG,IGT,IFG+IGT and T2DM groups;△I30/△G30 was decreased by 34%,44%,53% and 83%.AUCI was decreased by 18%,24% and 39% respectively in IFG,IFG+IGT and T2DM.⑤There was no correlation between 8-OHdG and age,DBP,BMI,UA (P>0.05).There was positive correlation between 8-OHdG and SBP(r=0.22, P<0.05),FBG(r=0.42, P<0.01),TG(r=0.24,P<0.05),CHO(r=0.40,P<0.01),LDL-C(r=0.28,P<0.05),HbA1c(r=0.52,P<0.01),lnHOMA-IR(r=0.27,P<0.05). There was negative correlation between 8-OHdG and lnHOMA-β(r=-0.34, P<0.01),ln△I30/△G30(r=-0.69,P<0.01),lnAUCI (r=-0.24,P<0.05).Conclusions1. From NGT,IFG,IGT,IFG+IGT to T2DM,the serum 8-OHdG level was getting higher.DNA oxidative injury was existed in early and pre-diabetes and the serum 8-OHdG level incerased as the extend of DNA oxidative injury.2. IFG was mainly expressed in lack of insulin secretion and liver insulin resistance; IGT was mainly expressed in impaired early insulin secretion. DM patients were with both severe IR andβ-cell defects.3.Insulin resistance andβ-cell function decline was an important pathophy- siological changes in type 2 diabetes mellitus and emerged before the diagnosis of diabetes.4.8-OHdG could be used as early evaluation of insulin resistance and isletβ-cell injury, 8-OHdG could be used as indicator of early prevention of diabetes.
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