Hindawi Publishing CorporationEvidence-Based Complementary and Alternative MedicineVolume 2013, Article ID 851267, 11 pageshttp://dx.doi.org/10.1155/2013/851267

Research ArticleAntihyperglycemic Effects of Short Term ResveratrolSupplementation in Type 2 Diabetic Patients

Ali Movahed,1 Iraj Nabipour,1 Xavier Lieben Louis,2,3,4

Sijo Joseph Thandapilly,2,3,4 Liping Yu,2,3 Mohammadreza Kalantarhormozi,1

Seyed Javad Rekabpour,1 and Thomas Netticadan2,3,4

1 Department of Endocrine and Metabolic Diseases, The Persian Gulf Tropical Medicine Research Center, Bushehr,University of Medical Sciences, Bushehr 7514763448, Iran

2Heart Failure Research Laboratory, Canadian Centre for Agri-Food Research in Health and Medicine,St. Boniface Research Centre, Winnipeg, MB, Canada R2H 2A6

3 Agriculture and Agri-Food Canada, Winnipeg, MB, Canada R3T 2M94Department of Physiology, University of Manitoba, Winnipeg, MB, Canada R3E 0J9

Correspondence should be addressed to Ali Movahed; amirali 1957@yahoo.com andThomas Netticadan; tnetticadan@sbrc.ca

Received 13 June 2013; Accepted 25 July 2013

Academic Editor: MinKyun Na

Copyright © 2013 Ali Movahed et al. This is an open access article distributed under the Creative Commons Attribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

The objective of this study was to examine the effectiveness of resveratrol in lowering blood glucose in the presence of standardantidiabetic treatment in patients with type 2 diabetes, in a randomized placebo-controlled double-blinded parallel clinical trial.A total of 66 subjects with type 2 diabetes were enrolled in this study and randomly assigned to intervention group which wassupplemented with resveratrol at a dose 1 g/day for 45 days and control group which received placebo tablets. Body weight,blood pressure, fasting blood glucose, haemoglobin A1c, insulin, homeostatic assessments for insulin resistance, triglycerides, totalcholesterol, low density lipoprotein, high density lipoprotein, and markers of liver and kidney damage were measured at baselineand after 45 days of resveratrol or placebo supplementation. Resveratrol treatment significantly decreased systolic blood pressure,fasting blood glucose, haemoglobin A1c, insulin, and insulin resistance, while HDL was significantly increased, when comparedto their baseline levels. On the other hand, the placebo group had slightly increased fasting glucose and LDL when compared totheir baseline levels. Liver and kidney function markers were unchanged in the intervention group. Overall, this study showed thatresveratrol supplementation exerted strong antidiabetic effects in patients with type 2 diabetes.

1. Background

The incidence of diabetes mellitus continues to rise world-wide, and it has far reaching consequences to the qual-ity of human life [1, 2]. Progression of uncontrolled dia-betes culminates inmicrovascular (retinopathy, nephropathy,and neuropathy) and macrovascular (cardiac, cerebral, andperipheral vascular disease) complications and prematuredeath [3, 4]. Among the two forms of diabetes, type 2 diabetesmellitus (T2DM) (formerly called non-insulin-dependentdiabetes mellitus) is the most prevalent one and is primarilycharacterized by insulin resistance and associated hyper-glycemia [5–7].

The most recent epidemiological data from the Interna-tional Diabetes Federation (IDF) has revealed that diabetescurrently affects around 371 million people globally and 4.8million die every year [8].Moreover, it has been proposed thatdeveloping countries will contribute to the majority (77.6%)of the diabetic patients globally, by the year 2030 [9, 10].Among these countries, Islamic Republic of Iran is one ofthe countries having the highest prevalence of T2DM [11, 12].These alarming epidemiological figures demonstrate the needof alternative therapeutic strategies, dietary interventions,and life style modifications, in addition to the existingpharmacological agents to prevent/manage T2DM in thesehigh risk populations.

4

2 Evidence-Based Complementary and Alternative Medicine

In the past decade, resveratrol, a naturally occurring poly-phenolic compound, found predominantly in grapes andpeanuts, has been widely documented in the scientific litera-ture for its beneficial effects in preventing and/or managingseveral diseases [13, 14]. Over the past 6 years, we havereported potent effects of resveratrol in preventing or revers-ing cardiac impairment in animal models of hypertensionand obesity [5, 15, 16]. In the obesemodel [5], we also reportedthat resveratrol reduced hyperglycemia. Several other studieshave also reported improvement in metabolic parametersin resveratrol treated animal models of insulin resistanceincluding T2DM [17–20].

Despite the strong evidence for resveratrol generatedfrom preclinical research and its widespread use as a nutri-tional supplement, well designed human clinical trials inves-tigating the antidiabetic effects of resveratrol are limited.To date, only two human studies have been completed toinvestigate the potential of resveratrol in T2DM patients[21, 22]. Both studies [21, 22] reported a modest reductionin blood glucose levels, while one showed no effect oninsulin levels [22]. Recently, Crandall et al. also showed aslight improvement in insulin sensitivity and postprandialplasma glucose in resveratrol treated prediabetic older adults[23]. However, two human clinical trials investigating themetabolic effects of resveratrol on insulin sensitivity andglucose response in obese subjects reported no clinicallysignificant effect on blood glucose [24, 25]; it must be notedthat these studies included relatively healthy (nondiabetic)subjects, and therefore the results cannot be extrapolatedto make decisive conclusions regarding the antidiabeticpotential of resveratrol. Given the discordant results achievedwith resveratrol treatment, further human clinical trials areneeded to establish the antidiabetic effects of resveratrol.

As stated earlier the increased risk and prevalence ofT2DM among Iranians make them an ideal study populationto test the efficacy of resveratrol in improving diabetes relatedmetabolic abnormalities. Accordingly, the primary objectiveof the present studywas to examinewhether supplementationwith resveratrol at a dose 1 g/day would have a clinicallyapparent blood glucose lowering effect, while the secondaryobjective was to assess the effects on insulin, metabolicmarkers, and cardiovascular risk factors. This study will alsoaddress whether resveratrol could complement the standardantidiabetic regimen [26] and render added protection inpatients with T2DM, in a randomized placebo-controlled,double-blinded parallel clinical trial.

2. Methods

2.1. Subjects and StudyDesign. Thestudywas approved by theMedical Ethics Committee of Bushehr University of MedicalSciences. The project was also registered with Clinical TrialRegistry of Iran (registration no: IRCT201111198129N1). Theinformed consent was obtained from each patient at the timeof enrolment and continued as a process throughout theinvestigation. Also, the patients had free medical care andconsultation during the study period, especially in the caseof any adverse reaction or complications.

Seventy patients with T2DM who repeatedly visited theEndocrine Clinic of the Persian Gulf Tropical MedicineResearch Center, Bushehr University of Medical Sciences,Bushehr, Iran, were enrolled in a randomized placebo-controlled double-blinded single centre clinical trial. The fol-lowing inclusion criteriawere used to recruit the subjects whohad T2DM: (1) age between 20 and 65 years, (2) minimumof 6 months on oral hypoglycemic treatment or combinationtherapy, (3) being not on any antioxidant therapy such asvitamin supplements, and (4) having no allergy to grapes,green tea, and peanuts. Patients with type 1 diabetes, pregnantwomen, lactating mothers, and patients with severe heartdisease, hepatic disease, and renal impairment were excludedfrom the present study. The patients were randomly assignedto control and intervention groups.

2.1.1. Randomization/Blinding Procedures. Stratified random-ization was used to allocate participants to the 2 treatmentsequences so that equal numbers of men and women willbe allocated to each sequence. Thereafter, randomization ofthe participants into treatment group and placebo groupwas done by computer generated numbered sequence codeswhich were given in opaque envelopes to subjects in thefirst study visit. Both the clinical team and participants wereblinded from the time of randomization until analysis wascompleted.

2.1.2. Compliance. At each visit (once a week during theintervention period), the participant returned unused cap-sule bottles. Study compliance was assessed by countingthe remaining capsules from the bottle every week. Everyparticipant was asked to complete a questionnaire duringeach visit to monitor the type of foods consumed during thestudy, particularly to confirm that they did not have foodproducts that may contain resveratrol. No other assessmentswere done during these routine visits.

2.2. Treatment Regime. The patients in the interventiongroup received 500mg, twice a day (a total of 1 g/day) ofresveratrol capsules (99% pure, Biotivia, Bioceuticals Inter-national SrI, Italy) for a period of 45 days. The control groupreceived 500mg twice daily of placebo capsules (totally inertmicrocellulose, Biotivia, Bioceuticals International SrI, Italy)supplementation for the same period of time. Since the studywas also intended to test the effectiveness of resveratrol whenadministered in conjunction with existing treatments againstT2DM, all patients were allowed to continue their existingantidiabetic medications during the course of the study.Oral hypoglycemic agents and insulin were not modifiedduring the course of the study. Among the participants whocompleted the study, in the control group, 12, 7, 10, and2 patients were on metformin, glibenclamide, metformin+ glibenclamide, and insulin + metformin, respectively. Inthe intervention group, 9, 10, 12, and 2 patients were onmetformin, glibenclamide, metformin + glibenclamide, andinsulin + metformin, respectively. Few subjects were alsounder atorvastatin (𝑛 = 3), atenolol (𝑛 = 1), simvastatin(𝑛 = 1), and lovastin (𝑛 = 1).

5

Evidence-Based Complementary and Alternative Medicine 5

Table 2: Anthropometric, clinical, and biochemical parameters for placebo and resveratrol groups before and after resveratrol supplementa-tion.

Control/placebo group Intervention/resveratrol group

Baseline After 45 days P value Baseline treatment After treatment P value

Body weight (kg) 76.60 ± 14.27 76.60 ± 14.16 0.809 74.26 ± 11.39 74.48 ± 11.34 0.712

BMI (kg/m2) 27.83 ± 4.21 27.69 ± 4.15 0.332 27.05 ± 3.13 27.16 ± 3.13 0.395

Systolic blood pressure (mmHg) 129.31 ± 15.16 130.68 ± 13.21 0.147 129.03 ± 14.91 121.45 ± 10.26 <0.0001∗

Diastolic blood pressure (mmHg) 78.58 ± 15.39 81.55 ± 5.84 0.279 76.93 ± 19.54 78.54 ± 6.35 0.169

Fasting glucose (mg/dL) 151.24 ± 51.52 161.13 ± 53.16 0.002∗ 175.74 ± 49.63 140.80 ± 39.74 <0.0001∗

Insulin (𝜇IU/mL) 9.04 ± 5.35 8.77 ± 4.16 0.642 10.20 ± 4.33 5.37 ± 2.62 <0.0001∗

HbA1c 8.30 ± 1.43 8.50 ± 2.46 0.764 8.6 ± 1.390 7.60 ± 1.32 <0.0001∗

HOMA-IR 3.20 ± 2.37 3.43 ± 1.83 0.423 4.61 ± 2.77 1.91 ± 1.17 <0.0001∗

HOMA-𝛽 36.13 ± 8.45 35.68 ± 7.95 0.039 32.15 ± 5.32 25.80 ± 4.43 0.009∗

Triglyceride (mg/dL) 134.69 ± 45.61 123.13 ± 43.27 0.145 160.1 ± 58.96 142.28 ± 52.61 0.051

Total cholesterol (mg/dL) 168 ± 41.97 175.34 ± 41.31 0.424 203.61 ± 52.70 192.28 ± 53.13 0.156

HDL-cholesterol (mg/dL) 41.73 ± 9.52 39.69 ± 10.83 0.133 41.40 ± 8.35 46.15 ± 8.40 0.001∗

LDL-cholesterol (mg/dL) 107.95 ± 31.67 117.18 ± 29.88 0.003∗ 134.04 ± 36.18 122.71 ± 38.19 0.106

SGOT (IU/L) 24.0 ± 5.47 25.0 ± 6.71 0.212 26.0 ± 5.87 26.0 ± 7.56 0.837

SGPT (IU/L) 19.44 ± 8.79 21.65 ± 8.67 0.202 21.45 ± 7.91 22.61 ± 9.74 0.365

GGT (IU/L) 30.82 ± 17.79 29.93 ± 17.01 0.545 32.12 ± 15.32 33.38 ± 17.92 0.441

ALP (IU/L) 169.37 ± 52.63 189.41 ± 48.38 0.001∗ 185.29 ± 59.35 190.64 ± 47.55 0.372

Creatinine (mg/dL) 0.92 ± 0.24 0.97 ± 0.25 0.281 0.96 ± 0.24 0.90 ± 0.21 0.098Data is presented asmeans± SD. ∗𝑃 < 0.05 versus before treatment.HOMA-𝛽: homeostasismodel of assessment for beta cell function;HOMA-IR: homeostasismodel of assessment for insulin resistance; HbA1c: Hemoglobin A1c; HDL: high density lipoprotein; LDL: low density lipoprotein; TG: triglyceride; SGOT:serum glutamate oxaloacetate transaminase; SGPT: serum glutamate pyruvate transaminase; GGT: gamma-glutamyltransferase; ALP: alkaline phosphatase.

(SGOT, SGPT, GGT, and ALP) and a kidney functionmarker(creatinine) were unchanged with resveratrol treatment for45 days in T2DM patients (when compared with baselinevalues). At the end of the study, ALP was significantlyincreased in the control group (Table 2). Glucose levels weresignificantly reduced with resveratrol treatment in T2DMpatients (when compared with baseline levels); patients incontrol group showed a small but significant increase inglucose levels (Table 2). There was a significant decrease inHbA1c in intervention group when compared to the baselinelevels, whereas, there was no change in HbA1c levels incontrol group (Table 2). Insulin levels in intervention groupwere significantly decreased when compared to baselinelevels, while control group had no change in insulin levels(Table 2). Homeostatic model assessment of insulin resis-tance (HOMA-IR) and beta cell function (HOMA-𝛽) showedthat both parameters were significantly decreased in inter-vention groupwhen compared to the baseline levels (Table 2);however, HOMA-IR did not change in control group, while,HOMA-𝛽marginally but significantly decreased (Table 2).

When compared with baseline, HDL levels were signifi-cantly increased in the intervention group. Changes in total

triglycerides, cholesterol, and LDL levels showed a decreasingtrend but were not statistically significant (Table 2). However,the control group had increased LDL levels at the endof the study when compared to the baseline levels, whiletriglycerides, total cholesterol, and HDL were unchanged(Table 2).

A comparison of the changes in the anthropometric,clinical, and biochemical measurements during the studyperiod (end of the study period minus baseline) between theintervention and control groups are shown is Table 3. Whencompared to the controls, a significant decline was observedin systolic blood pressure, HbA1c, HOMA-IR, serum fast-ing glucose, and insulin, while significant increment wasobserved in the levels of HDL-C (𝑃 < 0.0001) in the inter-vention group. When compared to the control group, nosignificant changes were found for BMI, body weight, dias-tolic blood pressure, HOMA-𝛽, levels of total cholesterol,creatinine, and liver enzymes in the subjects supplementedwith resveratrol.

Subgroup analyses were also done to determine if resver-atrol had any additive effect when combined with met-formin and glibenclamide.The seven parameters that showed

6

8 Evidence-Based Complementary and Alternative Medicine

supplementation. Accordingly, it may be suggested that shortterm supplementation with a moderate to high dose ofresveratrol (1 g/day) as used in the current study may helpto markedly lower blood glucose levels. We speculate that,once blood glucose levels are normalized, T2DM patientsmay be administered a lower dose (less than the 1 g/day) ofresveratrol that in conjunction with dietary modificationsand appropriate exercise regimenmay help maintain loweredblood glucose levels. Whether the use of a lower dose is aneffective option in the long term is a question that needs to betested in an independent clinical trial.

A major concern in using higher doses of resveratrol inhumans would be the possibility of toxic effects to majororgans in the body. However, in a recent well-designed dose-response study, Brown et al. reported that up to 1 g resveratrolwas well tolerated in human subjects and did not result intoxic effects, while 2.5 and 5 grams resulted in some gastroin-testinal symptoms [35]. Brown et al. study was conductedon healthy subjects, while another study on older adultsshowed that 1-2 g/day dosage of resveratrol was well toleratedwithout any changes in kidney or liver function markers[23]. Our data on organ damage markers also showed thattreatment with 1 g resveratrol caused no changes to liverfunction markers (SGOT, SGPT, GGT, and ALP), as wellas a kidney function marker (creatinine) in T2DM patients,indicating that short term resveratrol supplementation at amoderate to high dose had no adverse effects on liver andkidney. However, our study was only for 45 days, and longerstudies would be necessary to confirm the safety of resveratrolat different doses. As speculated earlier, use of a lower dose(<1 g) after the 45-day treatment with 1 g resveratrol mayeliminate or minimize, if any, resveratrol related toxicity inthe long term.On the other hand, it should bementioned thatthe control group which was on standard diabetic treatmentalone had an increase in alkaline phosphatase (ALP) levels,when compared to the baseline values.

Glycated hemoglobin (HbA1c) levels in blood are anotherstable marker for blood glucose levels [36]. It must be notedthat a decrease by one point in HbA1c levels observed inthe intervention group is clinically very significant, giventhat this was achieved with 45 days of treatment. Thisresult is comparable to decrease in HbA1c levels in T2DMpatients with metformin (a frontline glycemic control drug)administration [37]. Accordingly, this data provides furtherevidence for the effectiveness of resveratrol supplementationin maintaining the lowered blood glucose levels during thestudy period. There was also a striking decrease in insulinlevels, along with significant reductions in HOMA-IR andHOMA-𝛽 in the intervention group, suggesting that additionof resveratrol to standard antidiabetic therapy is beneficialin lowering insulin levels and improving insulin sensitivityand beta cell function in T2DM patients. Brasnyo et al.[22] did not observe any difference in serum insulin valueswith resveratrol treatment in type 2 diabetic patients, butthey noted a significant reduction in HOMA-IR values; alack of effect of resveratrol on serum insulin values may beattributed to the very low dose of resveratrol (10mg/day)used in their study. Although HOMA can be used in subjectstreatedwith insulin or in subjects on insulin secretagogues for

determining 𝛽-cell function over time [38], our results needto be interpreted with caution.

Type 2 diabetes is associated with increased risk ofischemic heart disease, and higher (than normal) LDLcholesterol levels and lower HDL levels, are independentrisk factors for ischemic heart disease [39, 40]. Our datashows that HDL levels were significantly increased in theintervention group.The increase inHDL levels by 4.75mg/dLwith resveratrol treatments was comparable to that achievedwith nicotinic acid [41].Therewere trends towards a decrease,but no significant changes were observed in triglycerides,cholesterol, and LDL levels with resveratrol supplementation,while a significant increase in LDL levels was observed in thecontrol group. Metformin, glibenclamide, and insulin are allknown to have beneficial or no effect on the lipid profiles [42];therefore, other independent factors may have contributed tothe observed increase in the control group.

Subgroup analyses showed that resveratrol may have anadded effect when used in combination with glibenclamideand metformin. However, the power of the current study forsubgroup analyses is weak; hence, the results should not beoverinterpreted [43].

5. Conclusion and Summary

The results of this study clearly demonstrate that resveratrolsupplementation in the presence of standard antidiabeticmedication has major benefits in T2DM patients, whichinclude a pronounced lowering of blood glucose, HbA1c,insulin levels, and insulin resistance, as well as improvementinHDL levels (Figure 2). Unlike earlier reports [21–23] whichshowedmild effects on hyperglycemia and hyperinsulinemia,our study highlights the marked changes and the potential ofresveratrol as an antidiabetic molecule. It is also importantto note the beneficial effects of resveratrol observed onmetabolic parameters, despite the fact that there was noappreciable effect on body weight or body composition.Some of the observed reductions in HbA1c and HDL withresveratrol supplementation are very significant that they canbe compared to benefits achieved with front line antidiabeticdrugs. Other important observations which stem from thisstudy are that: (a) 1 g/day of resveratrol supplementation for45 days had no adverse effects in type 2 diabetic patients and(b) resveratrol not only complemented standard antidiabeticmedication but also provided added protection (over stan-dard antidiabetic therapy).

5.1. Study Limitations. This is a pilot study which examinedthe antidiabetic effects of resveratrol over the short term, andonly one dose of resveratrol was tested.Therewas no followupto check the metabolic parameters of the patients after theresveratrol wash-out period.The study lacks the investigationof cellular mechanisms underlying the antidiabetic effects ofresveratrol. Extensive toxicological screening was not doneon subjects to confirm the safety of resveratrol administra-tion, and the safety of administering 1 g dose of resveratrolover the long term has not been established.

7

N U T R I T I O N R E S E A R C H X X ( 2 0 1 2 ) X X X – X X X

Ava i l ab l e on l i ne a t www.sc i enced i r ec t . com

www.n r j ou rna l . com

Communication

Resveratrol supplementation improves glycemic control intype 2 diabetes mellitus☆

Jayesh Kumar Bhatt a, Sabin Thomasb, Moola Joghee Nanjana ,⁎a JSS College of Pharmacy, Ootacamund, Tamilnadu, India 643001b School of Pharmacy, The University of Nizwa, Nizwa 616, Sultanate of Oman

A R T I C L E I N F O

Abbreviations: BMI, body mass index; DM,C, low-density lipoprotein cholesterol; T2DM☆ Duality of interest: The authors declare th⁎ Corresponding author. PG Studies & Researc

fax: +91 0423 2447135.E-mail address: mjnanjan@gmail.com (M

0271-5317/$ – see front matter © 2012 Elsevidoi:10.1016/j.nutres.2012.06.003

Please cite this article as: Bhatt JK, et al,Nutr Res (2012), doi:10.1016/j.nutres.2012

A B S T R A C T

Article history:Received 26 November 2011Revised 7 June 2012Accepted 8 June 2012

Resveratrol is a naturally occurring polyphenolic compound. Numerous animal studies havebeen reported on its wide-ranging beneficial effects in the biological system includingdiabetesmellitus (DM).Wehypothesized, therefore, that oral supplementation of resveratrolwould improve the glycemic control and the associated risk factors in patients with type 2diabetes mellitus (T2DM). The present clinical study was therefore carried out to test thehypothesis. Sixty-two patients with T2DM were enrolled from Government HeadquartersHospital, Ootacamund, India, in a prospective, open-label, randomized, controlled trial.Patients were randomized into control and intervention groups. The control group receivedonly oral hypoglycemic agents, whereas the intervention group received resveratrol (250mg/d) along with their oral hypoglycemic agents for a period of 3 months. Hemoglobin A1c, lipidprofile, urea nitrogen, creatinine, andproteinweremeasured at the baseline andat the endof3 months. The results reveal that supplementation of resveratrol for 3 months significantlyimproves the mean hemoglobin A1c (means ± SD, 9.99 ± 1.50 vs 9.65 ± 1.54; P < .05), systolicblood pressure (mean ± SD, 139.71 ± 16.10 vs 127.92 ± 15.37; P < .05), total cholesterol (mean ±SD, 4.70 ± 0.90 vs 4.33 ± 0.76; P< .05), and total protein (mean±SD, 75.6 ± 4.6 vs 72.3 ± 6.2; P< .05)in T2DM. No significant changes in body weight and high-density lipoprotein and low-density lipoprotein cholesterols were observed. Oral supplementation of resveratrol is thusfound to be effective in improving glycemic control and may possibly provide a potentialadjuvant for the treatment and management of diabetes.

© 2012 Elsevier Inc. All rights reserved.

Keywords:Type 2 diabetes mellitusResveratrolMetforminGlibenclamideGlycated hemoglobinHuman

1. Introduction

Diabetes mellitus (DM) is a common, serious, chronic, andcurrently incurable metabolic disorder of worldwide signifi-cance. India is identified as the diabetes capital of the world,with the current estimated 50.8 million diabetic patients. The

diabetes mellitus; HbA1c,, type 2 diabetes mellitusat there is no duality ofh, JSS College of Pharma

.J. Nanjan).

er Inc. All rights reserved

Resveratrol supplemen.06.003

worldwide prevalence is 285 million in 2010, and by 2030, thenumber is expected to increase to 438 million. Most will havetype 2 DM (T2DM) [1].

The disease is known to be associated with a high risk ofmicrovascular and macrovascular complications and veryoften leads to premature death. Despite the availability of

hemoglobin A1c; HDL-C, high-density lipoprotein cholesterol; LDL-.interest associated with this manuscript.cy, Ootacamund, Tamilnadu, India 643001. Tel.: +91 0423 2447135;

.

tation improves glycemic control in type 2 diabetes mellitus, 8

Tab

le2–Bioc

hem

ical

andclinical

variab

lesat

base

linean

dafter3m

onth

sforth

eco

ntrol

andinterven

tion

grou

ps

Variables

Con

trol

grou

p(n

=29

)P

Interven

tion

grou

p(n

=28

)P

Base

line

After

3m

oBa

selin

eAfter

3m

o

Body

weigh

t,kg

63.10±9.02

63.31±8.92

.45

64.78±9.25

64.94±9.00

.83

BMI,kg

/m2

24.92±3.05

24.86±2.89

.57

24.66±3.57

24.60±3.62

.83

Fastingbloo

dgluco

se,m

mol/L

and(m

g/dL

)10

.11±2.56

(182

±46

.22)

10.83±2.92

(195

.03±52

.56)

.05⁎

11.82±3.58

(212

.82±64

.52)

11.02±3.86

(198

.43±69

.57)

.29

HbA

1c,m

mol/L

[2.4-4.7]a

nd

(perce

ntage

oftotalh

emog

lobin)[3.9-5.1]

11.4

±−1.9(8.75±1.56

)11

.7±−1.7(8.92±1.65

).15

13.7

±−2(9.99±1.50

)13

.1±−1.9(9.65±1.54

).02⁎⁎

Systolic

bloo

dpr

essu

re,m

mHg

134.51

±14

.61

142.27

±12

.99

.000

7⁎⁎

139.71

±16

.10

127.92

±15

.37

.000

2⁎⁎

Diastolic

bloo

dpr

essu

re,m

mHg

78.62±10

.86

85.72±9.14

.000

1⁎⁎⁎

81.42±9.58

79.28±9.71

.20

Total

choles

tero

l,mmol/L

[2.59-6.21

]and(m

g/dL

)[10

0-24

0]4.89

±0.89

(191

.03±34

.91)

5.07

±0.90

(197

.93±35

.22)

.007

⁎⁎4.70

±0.90

(183

.5±35

.16)

4.33

±0.76

(169

.17±29

.85)

.004

⁎⁎

Triglyc

eride,

mmol/L

[0.56-1.98

]and(m

g/dL

)[50

-175

]1.89

±0.59

(168

.62±53

.21)

1.92

±0.56

(171

.42±50

.25)

.36

1.70

±0.63

(151

.64±56

.92)

1.71

±0.74

(152

.39±66

.51)

.94

LDL-C,m

mol/L

[<2.6]

and(m

g/dL

)[<10

0]2.80

±0.80

(108

.34±31

.01)

2.98

±0.79

(115

.43±30

.66)

.01⁎⁎

2.58

±0.83

(99.96

±32

.18)

2.26

±0.65

(87.51

±25

.23)

.05⁎

HDL-C,m

mol/L

[0.90-1.68

]and(m

g/dL

)[35

-65]

1.26

±0.17

(48.96

±6.92

)1.21

±0.24

(46.96

±9.51

).21

1.37

±0.27

(53.28

±10

.78)

1.32

±0.25

(51.25

±9.88

).42

Ureanitro

gen,m

mol/L

[3.6-17.8]

and(m

g/dL

)[10

-50]

10.44±1.42

(29.27

±3.99

)10

.51±1.33

(29.44

±3.73

).62

11.78±2.11

(33±5.92

)10

.60±2.59

(29.71

±7.27

).02⁎⁎

Creatinine,

mmol/L

[44.2-11

4.9]

and(m

g/dL

)[0.5-1.3]

83.98±9.72

(0.95±0.11

)87

.51±7.95

(0.99±0.09

).02⁎⁎

90.16±15

.02(1.02±0.17

)91

.93±17

.68(1.04±0.20

).56

Total

protein,g

/L[63-84

]and(g/dL)

[6.3-8.4]

76.5

±3.5(7.65±0.35

)77

.3±2.97.73

±0.29

.72⁎

75.6

±4.67.56

±0.46

72.3

±6.27.23

±0.62

.04⁎⁎

Figu

resin

squarebrac

kets

referto

nor

mal

reference

range

inth

elabo

ratory.V

alues

areex

pres

sedas

mea

ns±SD

(Stu

dentpa

ired

ttest

was

use

d).

⁎Not

quitesign

ifican

t.⁎⁎

P<.05.

⁎⁎⁎P<.001

.

Table 3 – Change in the biochemical and clinical variablesduring the study period (end of the study minus baseline)for the control and intervention groups

Variables Control group(n = 29)

Interventiongroup (n = 28)

P

BMI (kg/m2) −0.06 ± 0.16 −0.06 ± 0.05 .99Fasting bloodglucose (mg/dL)

13.07 ± 6.34 - 14.39 ± 5.05 .0001 ⁎

HbA1c (mmol/L)(percentage of totalhemoglobin)

0.17 ± 0.10 −0.33 ± 0.04 .0001 ⁎

Systolic bloodpressure (mm Hg)

7.76 ± 1.62 −11.78 ± 0.73 .0001 ⁎

Diastolic bloodpressure (mm Hg)

7.10 ± 1.72 −2.14 ± 0.13 .0001 ⁎

Total cholesterol(mg/dL)

6.90 ± 0.31 −14.32 ± 5.31 .0001 ⁎

Triglyceride (mg/dL) 2.80 ± 2.96 0.75 ± 9.59 .2768LDL-C (mg/dL) 7.09 ± 0.35 −12.45 ± 6.95 .0001 ⁎

HDL-C (mg/dL) −2 ± 2.59 −2.03 ± 0.90 .95Urea nitrogen(mg/dL)

0.17 ± 0.26 −3.28 ± 1.35 .0001 ⁎

Creatinine (mg/dL) 0.04 ± 0.02 0.01 ± 0.03 .0001 ⁎

Total Protein (g/dL) 0.08 ± 0.06 −0.32 ± 0.16 .0001 ⁎

Values are expressed as means ± SD.Mean values were significantly different from control group(independent sample t test or Mann-Whitney U test).⁎ P < .0001.

4 N U T R I T I O N R E S E A R C H X X ( 2 0 1 2 ) X X X – X X X

Please cite this article as: Bhatt JK, et al, Resveratrol supplementNutr Res (2012), doi:10.1016/j.nutres.2012.06.003

premature death. Indian races and ethnic groups are prone tothese complications. Not only hyperglycemia but also distur-bances of lipid metabolism are among the major causes ofchronic diabetic complications. In the present study, resver-atrol supplementation significantly decreases total cholester-ol and LDL-C.

During the study period, it was observed that the systolicblood pressure in the control group increased significantly,whereas in the intervention group, it decreased significantly.No significant differencewas observed in theweight of controland intervention groups, which may be explained by theirnormal BMI at the time of enrollment.

In conclusion, the results of the present study support ourhypothesis that resveratrol supplementation improves glyce-mic control and the associated risk factors in patients withT2DM. The study also suggests that resveratrol could be usedas an effective adjuvant therapy [21] with a conventionalhypoglycemic regimen to treat T2DM.

Our preliminary study provides data about the possibleclinical effects of resveratrol supplementation on the glycemiccontrol and cardiovascular risk factors in patients with T2DMand a base for future studies with larger number of patientsand longer duration. Further studies on these lines arein progress.

Acknowledgment

The authors thank the Indian Council of Medical Research forthe award of a Senior Research Fellowship to Jayesh KumarBhatt and Biotivia Bioceuticals International, United States,for their generous gift of resveratrol capsules. All authors have

ation improves glycemic control in type 2 diabetes mellitus, 9

Satya Dash, Changting Xiao, Cecilia Morgantini, Linda Szeto and Gary F. LewisProduction in Overweight/Obese Men

High-Dose Resveratrol Treatment for 2 Weeks Inhibits Intestinal and Hepatic Lipoprotein

Print ISSN: 1079-5642. Online ISSN: 1524-4636 Copyright © 2013 American Heart Association, Inc. All rights reserved.

Greenville Avenue, Dallas, TX 75231is published by the American Heart Association, 7272Arteriosclerosis, Thrombosis, and Vascular Biology

published online September 26, 2013;Arterioscler Thromb Vasc Biol. 

http://atvb.ahajournals.org/content/early/2013/09/26/ATVBAHA.113.302342World Wide Web at:

The online version of this article, along with updated information and services, is located on the

http://atvb.ahajournals.org/content/suppl/2013/09/26/ATVBAHA.113.302342.DC1.htmlData Supplement (unedited) at:

http://atvb.ahajournals.org//subscriptions/at:

is onlineArteriosclerosis, Thrombosis, and Vascular Biology Information about subscribing to Subscriptions:

http://www.lww.com/reprints Information about reprints can be found online at: Reprints:

document. Question and AnswerPermissions and Rightspage under Services. Further information about this process is available in the

which permission is being requested is located, click Request Permissions in the middle column of the WebCopyright Clearance Center, not the Editorial Office. Once the online version of the published article for

can be obtained via RightsLink, a service of theArteriosclerosis, Thrombosis, and Vascular Biologyin Requests for permissions to reproduce figures, tables, or portions of articles originally publishedPermissions:

by guest on September 27, 2013http://atvb.ahajournals.org/Downloaded from by guest on September 27, 2013http://atvb.ahajournals.org/Downloaded from by guest on September 27, 2013http://atvb.ahajournals.org/Downloaded from by guest on September 27, 2013http://atvb.ahajournals.org/Downloaded from by guest on September 27, 2013http://atvb.ahajournals.org/Downloaded from by guest on September 27, 2013http://atvb.ahajournals.org/Downloaded from by guest on September 27, 2013http://atvb.ahajournals.org/Downloaded from by guest on September 27, 2013http://atvb.ahajournals.org/Downloaded from by guest on September 27, 2013http://atvb.ahajournals.org/Downloaded from by guest on September 27, 2013http://atvb.ahajournals.org/Downloaded from by guest on September 27, 2013http://atvb.ahajournals.org/Downloaded from by guest on September 27, 2013http://atvb.ahajournals.org/Downloaded from by guest on September 27, 2013http://atvb.ahajournals.org/Downloaded from by guest on September 27, 2013http://atvb.ahajournals.org/Downloaded from by guest on September 27, 2013http://atvb.ahajournals.org/Downloaded from 1

1

Increased production of triglyceride-rich lipoproteins (TRL), in the form of apolipoprotein B (apoB)-100 containing very

low-density lipoprotein (VLDL) from the liver and apoB-48 containing chylomicrons from the gut, in conditions such as overweight/obesity and insulin resistance, may contribute to an increased risk of atherosclerotic disease.1,2 Recently, we have shown that, in healthy human volunteers, intestinal secre-tion of apoB-48–containing TRL particles is regulated by free fatty acids,3 dietary monosaccharides (glucose and fructose),4 and hormones such as insulin5 and glucagon-like peptide-1.6 Individuals with obesity/overweight,2 insulin resistance,7 and type 2 diabetes mellitus8 have increased production of apoB-48 TRL particles. This, along with the well-established overproduction of apoB-100-containing VLDL by the liver,1 contributes to the elevated TRL seen in these individuals. Identifying novel strategies to lower TRL production by the liver and intestine may have clinical benefits in conditions

such as in overweight/obese states. In the present study, we have examined the effect of resveratrol in overweight and obese men with relatively mild metabolic abnormalities.

Polyphenol resveratrol, widely available over the counter, has been demonstrated to have numerous beneficial meta-bolic effects in vitro and in vivo in murine models. In vitro studies in hepatocytes have demonstrated that resveratrol reduces de novo lipogenesis.9 Resveratrol administration in vivo protects mice from diet-induced obesity, insulin resis-tance, and hepatic steatosis.10,11 Some, but not all,12,13 studies in humans have shown that resveratrol improves insulin sen-sitivity14–16 and lowers plasma triglyceride.14 The metabolic effects of resveratrol are thought to be mediated at least in part via indirect activation of AMP kinase and the NAD+-dependent deacetylase silent mating type information regula-tion 2 homolog (sirtuin) 1 (SIRT1).17 Adenine monophosphate kinase (AMPK) has multiple effects on lipid metabolism by

© 2013 American Heart Association, Inc.

Arterioscler Thromb Vasc Biol is available at http://atvb.ahajournals.org DOI: 10.1161/ATVBAHA.113.302342

Objective—Overproduction of hepatic apolipoprotein B (apoB)-100 containing very low-density lipoprotein particles and intestinal apoB-48 containing chylomicrons contributes to hypertriglyceridemia seen in conditions such as obesity and insulin resistance. Some, but not all, preclinical and clinical studies have demonstrated that the polyphenol resveratrol ameliorates insulin resistance and hypertriglyceridemia. Here, we assessed intestinal and hepatic lipoprotein turnover, in humans, after 2 weeks of treatment with resveratrol (1000 mg daily for week 1 followed by 2000 mg daily for week 2) or placebo.

Approach and Results—Eight overweight or obese individuals with mild hypertriglyceridemia were studied on 2 occasions, 4 to 6 weeks apart, after treatment with resveratrol or placebo in a randomized, double-blinded, crossover study. Steady-state lipoprotein kinetics was assessed in a constant fed state with a primed, constant infusion of deuterated leucine. Resveratrol treatment did not significantly affect insulin sensitivity (homeostasis model of assessment of insulin resistance), fasting or fed plasma triglyceride concentration. Resveratrol reduced apoB-48 production rate by 22% (P=0.007) with no significant effect on fractional catabolic rate. Resveratrol reduced apoB-100 production rate by 27% (P=0.02) and fractional catabolic rate by 26% (P=0.04).

Conclusions—These results indicate that 2 weeks of high-dose resveratrol reduces intestinal and hepatic lipoprotein particle production. Long-term studies are needed to evaluate the potential clinical benefits of resveratrol in patients with hypertriglyceridemia, who have increased concentrations of triglyceride-rich lipoprotein apoB-100 and apoB-48.

Clinical Trial Registration—URL: www.clinicaltrials.gov. Unique identifier: NCT01451918. (Arterioscler Thromb Vasc Biol. 2013;33:00-00.)

Key Words: apolipoproteins B ◼ chylomicrons ◼ intestines ◼ lipoproteins, VLDL ◼ resveratrol

Received on: June 10, 2013; final version accepted on: September 15, 2013.From the Department of Medicine, Physiology, and the Banting and Best Diabetes Centre, University of Toronto, Ontario, Canada (S.D., C.X., C.M.,

L.S., G.F.L.); and Scuola Superiore Sant’Anna, Pisa, Italy (C.M.).*These authors contributed equally to this article.The online-only Data Supplement is available with this article at http://atvb.ahajournals.org/lookup/suppl/doi:10.1161/ATVBAHA.113.302342/-/DC1.Correspondence to Gary F. Lewis, MD, FRCPC, Toronto General Hospital, 200 Elizabeth St, EN12-218, Toronto, Ontario M5G 2C4, Canada. E-mail

gary.lewis@uhn.ca

High-Dose Resveratrol Treatment for 2 Weeks Inhibits Intestinal and Hepatic Lipoprotein Production in

Overweight/Obese MenSatya Dash,* Changting Xiao,* Cecilia Morgantini, Linda Szeto, Gary F. Lewis

Original Article

2

Research Design and Methods

Participants

8 overweight or obese individuals (BMI range 27-40) with mild to moderate

hypertriglyceridemia (TG >1.5, range 1.6-3.9 mmol/l) were recruited via advertisements in

the local press. Their demographic and biochemical parameters are shown in Table 1.

Participants had no prior medical illnesses and were taking no medications. They underwent

a 2-hour, 75 gram oral glucose tolerance test, routine screening blood tests and urinalysis.

Those with evidence of diabetes, anemia, coagulopathy, renal dysfunction or impaired liver

function tests were excluded. The Human Research Ethics Board of the University Health

Network, University of Toronto, approved the study and all subjects gave written, informed

consent prior to their participation.

Each participant was studied on 2 occasions, 4-6 weeks apart, in a randomized, double blind,

crossover trial. They were randomized to receive two weeks of placebo or resveratrol

(Transmax, Biotivia Longevity Biologicals, New York, NY) [1g/d (500mg twice per day) for

one week, followed by 2g/d (1g twice per day) for the second week] preceding the

lipoprotein kinetics study. Each participant was reviewed after one week of treatment to

ensure there were no adverse effects and to ensure compliance by pill counting.

Lipoprotein kinetic studies

Participants were admitted to the Metabolic Test Centre of the Toronto General Hospital

after two weeks of treatment. Fasting blood samples were taken for measurement of

plasma glucose, insulin and lipids. They had a standardized meal comprising rice, chicken,

vegetables and jell-o at 5pm on both occasions. The following day a lipoprotein kinetics

3

Journal of Gerontology: MEDICAL SCIENCES © The Author 2012. Published by Oxford University Press on behalf of The Gerontological Society of America.Cite journal as: J Gerontol A Biol Sci Med Sci All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.doi:10.1093/gerona/glr235

1

RESVERATROL (3,5,4′-trihydroxystilbene) is a plant-derived polyphenolic compound mainly known for its

antioxidant and phytoestrogenic properties. Interest in this compound has increased in recent years, first from its iden-tification as a chemopreventive agent for skin cancer and subsequently from reports that it activates sirtuins and extends the life span of lower organisms, including rodents (1). Resveratrol has demonstrated promising effects on insulin secretion, insulin sensitivity, and glucose tolerance in a variety of animal models (2,3). Notably, resveratrol pre-vented the negative metabolic effects of excess calorie intake, improving glucose tolerance, lowering insulin levels, and significantly increasing survival of middle-aged mice (4). Resveratrol has also been shown to increase mitochondrial biogenesis and appears to mimic the beneficial effects of caloric restriction on glucose metabolism (5–7).

Resveratrol has also been proposed to have cardioprotective effects. Resveratrol possesses weak activity as a phytoes-trogen (8), antioxidant properties (9), and has been shown to both enhance synthesis and decrease inactivation of

the vasorelaxant nitric oxide (10). Resveratrol may also promote vascular relaxation by inhibiting synthesis of the potent vasoconstrictor thromboxane A2 and by other nitric oxide-independent mechanisms (11).

However, despite the many health claims made on its behalf and its widespread use as a nutritional supplement, formal studies of resveratrol in humans are very limited and no studies of its metabolic effects have been reported. Further, questions about resveratrol bioavailability, dosing range, and safety also need to be addressed (12–14). We therefore conducted a pilot study of resveratrol treatment as an initial step in assessing its potential to improve glucose tolerance, insulin sensitivity, and vascular function. For this initial in-vestigation, we studied the effects of resveratrol in subjects with impaired glucose tolerance (IGT) who have definite but not-yet-severe metabolic dysregulation, which may be most amenable to intervention. We chose to focus on older adults for two important reasons. First, IGT is in large part an age-related phenomenon, affecting up to 30% of older adults (15) and constitutes a major risk factor for

Pilot Study of Resveratrol in Older Adults With Impaired Glucose Tolerance

Jill P. Crandall,1,2,3 Valerie Oram,1 Georgeta Trandafirescu,1,2 Migdalia Reid,1 Preeti Kishore,1,2,3 Meredith Hawkins,1,2,3 Hillel W. Cohen,4 and Nir Barzilai1,2,3

1Division of Endocrinology, Department of Medicine, 2Diabetes Research and Training Center, 3Institute of Aging Research, and 4Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, New York.

Address correspondence to Jill P. Crandall, MD, 1300 Morris Park Avenue, Belfer 701, Bronx, NY 10461. Email: jill.crandall@einstein.yu.edu

Background. Resveratrol, a plant-derived polyphenol, has shown promising effects on insulin sensitivity and glucose tolerance in animal models and is also reported to have cardioprotective properties, but human studies are limited. In a pilot study, we tested the hypothesis that resveratrol improves glucose metabolism and vascular function in older adults with impaired glucose tolerance (IGT).

Methods. Ten subjects aged 72 ± 3 years (M ± SD) with IGT were enrolled in a 4-week open-label study of resveratrol (daily dose 1, 1.5, or 2 g). Following a standard mixed meal (110 g carbohydrate, 20 g protein, 20 g fat), we measured 3-hour glucose and insulin area under the curve (AUC), insulin sensitivity (Matsuda index), and secretion (corrected insulin response at 30 minutes). Endothelial function was assessed by reactive hyperemia peripheral arterial tonometry (reactive hyperemia index) before and 90 minutes postmeal. Results did not differ by dose, so data were combined for analysis.

Results. At baseline, body mass index was 29 ± 5 kg/m2, fasting plasma glucose 110 ± 13 mg/dL, and 2-hour glucose 183 ± 33 mg/dL. After 4 weeks of resveratrol, fasting plasma glucose was unchanged, but peak postmeal (185 ± 10 vs 166 ± 9 mg/dL, p = .003) and 3-hour glucose AUC (469 ± 23 vs 428 ± 19, p = .001) declined. Matsuda index improved (3.1 ± 0.5 vs 3.8 ± 0.5, p = .03), and corrected insulin response at 30 minutes was unchanged (0.6 ± 0.1 vs 0.5 ± 0.5, p = .49). There was a trend toward improved postmeal reactive hyperemia index (baseline vs resveratrol postmeal delta −0.4 ± 0.2 vs 0.2 ± 0.3, p = .06). Weight, blood pressure, and lipids were unchanged.

Conclusions. At doses between 1 and 2 g/day, resveratrol improves insulin sensitivity and postmeal plasma glucose in subjects with IGT. These preliminary findings support the conduct of larger studies to further investigate the effects of resveratrol on metabolism and vascular function.

Received July 12, 2011; Accepted November 13, 2011

Decision Editor: Luigi Ferrucci, MD, PhD

at Albert E

instein College of M

edicine on January 4, 2012http://biom

edgerontology.oxfordjournals.org/D

ownloaded from

10

CRANDALL ET AL.2

the development of both diabetes and cardiovascular disease (16). In addition, although lifestyle modification was excep-tionally effective in preventing progression from IGT to diabe-tes in older participants (age 60–85) in the Diabetes Prevention Program, metformin was not (17), highlighting the need for alternate pharmacologic approaches for older adults with IGT.

MethodsAdults aged 65 and older were screened with a 75-g oral

glucose tolerance test and those with fasting plasma glucose <126 mg/dL and 2-hour glucose ≥140 mg/dL were eligible to enroll. Subjects were excluded if they had a recent car-diovascular event, evidence of significant liver or renal dis-ease; any active cancer; or prior history of estrogen-dependent neoplasm. Because of the possibility of CYP450-related drug interactions (18), treatment with the following drugs was exclusionary: antiepileptics, mexilitene, quinidine, cyclo-sporine, tacrolimus, HIV protease inhibitors, or high-dose statin therapy (>20 mg atorvastatin or rosuvastatin; >40 mg simvastatin, pravastatin, or lovastatin). Individuals taking resveratrol or antioxidant vitamins (other than a standard mul-tivitamin preparation) within the prior 3 months were also ex-cluded. The study protocol was approved by the Albert Einstein College of Medicine Institutional Review Board, and all par-ticipants provided written informed consent.

Resveratrol capsules were obtained from Biotiva, LLC, and independent verification of the resveratrol content of the capsules used in this study was performed in the labora-tory of Rong-Fong Shen, PhD, Proteomics and Analytical Biochemistry Unit, National Institute on Aging at the National Institutes of Health. Subjects were randomly assigned to take open-label resveratrol for 4 weeks in one of the three doses: 1, 1.5, and 2 g/day, taken in divided doses. Subjects were instructed to maintain their usual dietary and physical activity patterns during their participation in the study.

Standard Meal TestSubjects were studied following an overnight fast and

after a test meal containing 110 g carbohydrate, 20 g protein, and 20 g fat. The meal consisted of standard breakfast foods: cereal, bread, juice, and milk. Blood sampling was performed fasting and 30, 60, 120, and 180 minutes following the meal through an indwelling intravenous catheter. Subjects were instructed to consume a standard meal and snack at home on the night prior to the standard meal test, in order to mini-mize metabolic variability between tests. The assigned resve-ratrol dose was administered with the standard meal during the test conducted at the conclusion of the 4-week treatment period. Insulin sensitivity was estimated using homeostasis model assessment (HOMA-IR): insulinfasting (mU/mL) × glucosefasting (mmol/L)/22.5 (19) and also from insulin and glucose levels obtained following the standard meal chal-lenge using the Matsuda index: 10,000/√([fasting plasma glucose × fasting plasma insulin] [mean glucose × mean

insulin]) (20,21). Insulin secretion was estimated using the corrected insulin response at 30 minutes: insulin30min (mU/mL)/glucose30min (mg/dL) × (glucose30min [mg/dL] − 70) (19). b-Cell function was assessed using the oral disposition index (DIO) calculated using the formula: (DI0–30/DG0–30) (1/I0) (22). Insulin and glucose area under the curve (AUC) were calcu-lated using the trapezoidal method. Percent body fat was mea-sured using bioimpedance analysis (RJL Systems, Clinton Township, MI).

Endothelial function testing was performed fasting and 90 minutes following the standard meal, using reactive hyperemia peripheral arterial tonometry (RH-PAT) (23,24). RH-PAT employs a finger plethysmographic device to detect pulsatile arterial volume changes, which are sensed by a pressure transducer and transferred to a computer for analysis (EndoPAT; Itamar Medical). Studies are performed with the patient at rest, in a comfortable thermoneutral envi-ronment, and any antihypertensive medications were held until after completion of the 90-minute postmeal test. Fin-gertip probes are placed on the index finger of both hands, and 5 minutes of baseline recording is obtained. Blood flow is then occluded in one arm for 5 minutes, using a standard blood pressure cuff. Recording continues in both fingers during occlusion and for 5 minutes after release of the cuff. The reactive hyperemia index is calculated as the ratio of the average pulse amplitude in the posthyperemic phase divided by the average baseline amplitude, with nor-malization to the signal in the control arm to compensate for any systemic changes. Test–retest repeatability testing in our laboratory among healthy controls resulted in a coeffi-cient of variability of 15.2% for tests performed 2 hours apart and 16.4% for tests performed 1–4 weeks apart.

Assays were performed in the core laboratories of the Einstein Institute for Clinical and Translational Research: chemistry profiles, complete blood count, urinalysis, glucose, lipoproteins, insulin (radioimmunoassay), high sensitivity c-reactive protein (latex-enhanced tur bidimetric assay), and adiponectin (radioimmunoassay; Linco).

Statistical AnalysisData are presented as mean (±SD) for baseline values and

mean (±SEM) for baseline versus resveratrol comparisons. Baseline and posttreatment variables (peak and AUC glucose, insulin, Matsuda index, etc.) were compared using a paired t-test. Since there were no apparent differences among the three resveratrol doses studied, the groups were combined for analysis. For RH-PAT index, the pre- and postmeal delta was also analyzed (baseline vs resveratrol) using paired t-test. Data analyses were performed using GraphPad Instat, v3.

ResultsTen subjects (seven female) with a mean age of 72 ± 3

years were enrolled. The subjects were overweight to obese and moderately insulin resistant, with a mean body mass

at Albert E

instein College of M

edicine on January 4, 2012http://biom

edgerontology.oxfordjournals.org/D

ownloaded from

11