Journal of Diabetes and Its Complications 27 (2013) 75–77

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Journal of Diabetes and Its Complications

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The effect of hydrochloride pioglitazone on urinary 8-hydroxy -deoxyguanosineexcretion in type 2 diabetics☆

Yuefen Wang, Shandong Ye ⁎, Yuanyuan Hu, Lili Zhao, Mao ZhengDepartment of Endocrinology, Anhui Provincial Hospital Affiliated to Anhui Medical University, Hefei 230001, PR China

☆ There are no conflicts of interest.⁎ Corresponding author.

E-mail address: ysd196406@163.com (S. Ye).

1056-8727/$ – see front matter © 2013 Elsevier Inc. Alhttp://dx.doi.org/10.1016/j.jdiacomp.2012.08.004

a b s t r a c t

a r t i c l e i n f o

Article history:

Received 29 June 2012Received in revised form 10 August 2012Accepted 14 August 2012Available online 26 September 2012

Keywords:Diabetic nephropathy8-hydroxy -deoxyguanosinePioglitazone

Objective: To observe the effects of hydrochloride pioglitazone on urinary 8-hydroxy-deoxyguanosine(8OHdG) excretion in type 2 diabetics and explore its possible reno-protective mechanisms.Methods: Ninety-eight uncontrolled type 2 diabetics were assigned randomly into group DP (pioglitazoneadd-on) and group DS (sulfonylureas add-on). At the basal and after 12weeks treatment, FBG, HbA1c, urinary8-OHdG, urinary albumin(ALB) and urinary creatinine (Cr) were determined, respectively.Results: Compared with pre-treatment, FBG, HbA1c and urinary 8-OHdG /Cr ratio(U8CR) were all obviouslydecreased in both therapy groups; urinary albumin/urinary creatinine ratio(UACR) markedly decreased ingroup DP (Pb0.01), while slightly decreased in group DS (PN0.05) after twelve weeks of observation. After12-week treatment, UACR and U8CR in group DP were significantly lower than those in group DS (both

Pb0.05) without no marked difference in FBG and HbA1c between group DP and group DS. Meanwhile, U8CRhad positive correlation with UACR (r=0.755, Pb0.01).Conclusion: Pioglitazone can decrease urinary 8-OHdG excretion and lighten oxidative stress in vivo in type 2diabetics, which may play a protective role for the kidney damage.

© 2013 Elsevier Inc. All rights reserved.

1. Introduction

Thiazolidinediones (TZDs), including pioglitazone and rosiglita-zone, exert their action by binding and acting on peroxisomeproliferator-activated receptor c (PPARc). Recent studies have shownthat TZDs exert a number of direct reno-protective effects, but Theexact mechanism(s) has not been thoroughly revealed (Sarafidis et al.,2010). Diabetes glucose metabolic disorder induced increase in ROSgeneration and oxidatie stress (Mohanty et al., 2000), which had beenconfirmed to participate in the occurrence of diabetic nephropathy(Coughlan, Mibus, & Forbes, 2008). Urinary 8-hydroxy-deoxyguanosine(8OHdG) is an excellent marker of oxidative DNA damage, whichincreaseed in diabetes (Dandona et al., 1996). The present study aims toobserve the effects of pioglitazone on urinary 8OHdG excretion indiabetics and explore its reno-protective mechanisms.

2. Materials and methods

2.1. Subjects

Ninety-eight type 2 diabetic patients with fasting blood glucose(FBG) levels between 7.0 and 13.0mm and glycated haemoglobin A1c

l rights reserved.

(HbA1c) ≥7.0% were recruited from the Department of Endocrinol-ogy, Anhui Provincial Hospital. All patients were aged between 35 and70 and had been treated previously with metformin or acarbose, or acombination of the two drugs. Patients with acute illness or chronicsystemic diseases were excluded from the study. We also excludedpatients who had taken statins, aldosterone receptor antagonists,angiotensin-converting enzyme inhibitors or angiotensin receptorantagonists in the 2-week period before the commencement of thestudy. The recruited patients were randomly assigned, usingcomputer generated random tables, to be treated with pioglitazone(group DP, N=49) or sulfonylurea (group DS,N=49). The study wasapproved by the local research ethics committee, and writteninformed consents were obtained from all subjects before thestudy commenced.

2.2. Methods

The patients in group DP received hydrochloride pioglitazone(Jiangsu Hengrui Medicine, Ltd, Lianyungang, China) at the dose from15 to 45 mg per day, while patients in group DS receivedsulfonylureas such as glimepiride (2–6 mg per day) or gliclazide(80–240mg per day) for 12 weeks. The dose of each drug was titratedin accordance with the patients’ blood glucose levels. All patientswere asked to keep their FBG and bedtime blood glucose between4.4 mmol/L and 8.3 mmol/L and the 2-h postprandial bloodglucoseb10 mmol/L. Gender, age, height, weight, waist circum-ference, hip circumference, systolic blood pressure (SBP), diastolic

Table 1Comparison of baseline characteristics between Group DP and Group DS.

(Values are expressed as x ±S)

Group DP Group DS

Age 52.56±9.40 52.02±9.07Number (M/F) 44(21/23) 46(24/22)Course (year) 6.54±4.71 6.42 ±3.75BMI (kg/m2) 24.02±3.46 23.16±4.33WHR 0.85±0.09 0.84±0.09SBP (mmHg) 138.29±16.17 139.76±22.33DBP (mmHg) 86.56±19.56 86.04±17.27FBG (mmol/L) 10.31±1.86 10.49±1.93HbA1c (%) 8.42±2.00 8.51±1.96

FBG, fasting blood glucose; SBP, systolic bloodpressure; DBP, diastolic blood pressure;HbA1c,glycated haemoglobin A1c. Values were expressed as x ±S.

76 Y. Wang et al. / Journal of Diabetes and Its Complications 27 (2013) 75–77

blood pressure(DBP), body mass index (BMI) and waist-hip ratio(WHR)were recorded. An overnight fasting venous blood sample wascollected to measure FBG, HbA1c. An early morning urine sample wascollected and preserved at −70°C to test urinary albumin (UALB),creatinine (Ucr), and 8OHdG .These measurements were repeatedafter 12-week treatment.

2.3. Statistical analysis

All data were expressed as means±SD and analysed by StatisticalPackage for the Social Sciences 13.0 (SPSS Inc., Chicago, IL, USA). Thedifferences between pre- and post-treatment were assessed by pairedt-tests in group DP and group DS, respectively. The changes betweengroups were assessed by independent-samples t-test. Correlationsanalysis was assessed by linear dependence relation. P-valuesb0.05were considered statistically significant.

3. Results

After 12-week observation, a total of 90 patients with type 2diabetes completed this trial with 44 in group DP and 46 in group DS.One patient was lost to follow-up, and four withdrew from the trial(three for noncompliance of target blood glucose and one for markedoedema of lower extremity) in group DP, while two patients lost tofollow-up and one withdrewwithout good control of blood glucose ingroup DS. At the end of the study, the average doses of pioglitazone,glimepiride and gliclazide were 25, 4 and 120 mg/day, respectively.

As shown in Table 1, no significant differences were found in age,gender, course, SBP, DBP, FBG and HbA1c between group DP andgroup DS.

After 12-week treatment, FBG and HbA1c significantly decreasedboth in group DP and group DS (Table 2), and the decreasedmagnitude had no significant differences between the two groups.U8CR decreased obviously in group DP(Pb0.01) and group DS(Pb0.01), however, the decreased magnitude was significantlydifferent between two groups(Table 2: −30% in group DP vs. −13%in group DS,Pb0.01). UACR decreased significantly in group

Table 2The comparisons of FBG, HbA1c, U8CR and UACR between the two groups and intra-group

Group FBG (mmol/L) HbA1c(%) U8CR(ng•mg-

Pretherapy Post-treatment Pretherapy Post-treatment Pretherapy

DP 10.31±1.86 6.98±1.10# 8.42±2.00 7.36±1.61# 22.25±5.78DS 10.49±1.93 6.70±1.20 # 8.51±1.96 7.22±1.28 # 21.03±4.02

U8CR, urinary 8OHdG/UCr ratio; UACR, UALB/UCr ratio. Values were expressed as x±S.# Pb0.01, Post-treatment vs. pre-therapy.★ Pb0.01, Group DS post-treatment vs. group DP post-treatment.Δ Pb0.05, Group DS post-treatment vs. group DP post-treatment.

DP(Pb0.01), while slightly without statistical significance in groupDS (Table 2).

In addition, the change of U8CR was positively correlated with thechange in UACR (r=0.755, Pb0.01).

4. Discussion

Recent studies (Balakumar, Kadian, & Mahadevan, 2012) havedemonstrated that TZDs can reduce urinary albumin excretion andameliorated glomerular sclerosis, then delay the progression ofdiabetic nephropathy (DN) independent of its hypoglycaemic effect.Toblli et al (Toblli et al., 2009). reported that treating type 2diabetes rats with pioglitazone (0.6 mg kg−1 per day) for 4–5months considerably reduced proteinuria and creatinine clearancerate, which associated with ameliorated renal fibrosis and preservedrenal function independent of glycaemic control. Similarly, Lee et al(Lee et al., 2007) suggested that pioglitazone (10 mg kg−1 per day)can reduce proteinuria and ameliorate DN beyond its hypoglycae-mic effect in Type 2 diabetic rats. Morikawa et al (Morikawa et al.,2011) demonstrated that combination of pioglitazone and renin-angiotensin system inhibitors showed therapeutic benefit in thereduction of urinary albumin excretion for type 2 diabetic patientswith hypertension and microalbuminuria after 52 weeks oftreatment. In this study, we found that pioglitazone loweredUACR more significantly than sulfonylurea, although they had asimilar glycaemic control, which indicated that pioglitazone had aneffective reno-protection not entirely dependent on glycaemiccontrol in diabetics.

Although the mechanisms responsible for diabetic nephropathy(DN) are not fully understood, accumulating evidences indicate thatoxidative stress has been demonstrated to be involved in theoccurrence and development of DN (Singh, Winocour, & Farrington,2011). High blood glucose levels can result in the overproduction ofreactive oxygen species (ROS) by cells and tissue. ROS generated invivo can cause oxidative damage to lipids, proteins and nucleic acids.As a result, the DNA is constantly being damaged and modifiedoxidatively. It should be noted that DNA oxidative damage can alsooccur from exogenous ROS. Normal DNA repair removes 8-OHdGadducts which are excreted andmeasurable in the urine (Breton et al.,2007; Wu et al., 2004). 8-OHdG in urine is a widely accepted markerof oxidative DNA damage and oxidative stress. Nishikawa et al. (2003)suggested that hyperglycemia independently increases urinary8-OHdG in patients with type 2 diabetes and urinary 8-OHdG is auseful biomarker of not only microvascular but also macrovascularcomplications in patients with type 2 diabetes. Previous research(Garg et al., 2000) has shown troglitazone has a potent and rapidbiological inhibitory effect on ROS generation. Our results showed thatpioglitazone had a similar effect of glycemic control compared tosulfonylurea, but a dramatical decrease in U8CR, which suggested thatpioglitazone decreased urinary 8-OHdG excretion independent of itshypoglycaemic effect. Further analysis found that urinary U8CR had apositive correlation with UACR in type 2 diabetics. The exactmechanism(s) of PPAR-γ agonists such as pioglitazone in lowering

before and after therapy.

1•Cr-1) UACR (mg•g-1•Cr-1)

Post-treatment rateofdecline Pretherapy Post-treatment rateofdecline

15.00±3.29#,★ 0.30±0.18 ★ 98.96±27.80 65.33±23.52#,Δ 0.36±0.16 ★

18.24±3.95 # 0.13±0.12 97.96±31.87 90.47±29.78 0.14±0.08

77Y. Wang et al. / Journal of Diabetes and Its Complications 27 (2013) 75–77

urinary 8-OHdG remain not entirely clear. It May be through thefollowing approaches: TZD-mediated activation of PPAR induces geneexpression of glutathione peroxidase 3 (GPx3), which reducesoxidative stress levels (Chung et al., 2009). Pioglitazone increasedPPAR expression and activity in the aging kidney, which paralleleddecreased oxidative stress (Yang et al., 2009).

5. Conclusion

In conclusion, our primary results showed that pioglitazone cansignificantly reduce the urinary albumin and 8-OHdG excretion intype 2 diabetics, and the effects were not entirely dependent onglycemic control.

Acknowledgments

The research presented in this article was financially supported bythe Foundation of Anhui Provincial Health Department ResearchProgram (NO.09A009) of China.

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