Effects of rosiglitazone and aspirin on experimental model of induced type [601432]

Effects of rosiglitazone and aspirin on experimental model of induced type
2 diabetes in rats: focus on insulin resistance and inflammatory markers
Amany A. Abdina,⁎, Amal A. Baalashb, Hala E. Hamoodab
aDepartment of Pharmacology, Tanta Faculty of Medicine, Tanta, Egypt
bDepartment of Medical Biochemistry, Tanta Faculty of Medicine, Tanta, Egypt
Received 31 January 2008; accepted 21 January 2009
Abstract
Both insulin resistance and decreased insulin secretion are major features of the pathophysiology of type 2 diabetes. Inflammatory
pathways are found to be critical in mechanisms underlying insulin resistance, which is a major determinant of increased risk of
cardiovascular complications in type 2 diabetes, and so, it is a potential therapeutic target. Thiazolidinediones (e.g., rosiglitazone) actprimarily as insulin sensitizers and were discovered to have anti-inflammatory effects leading to reevaluation of their potential use in
treatment of diabetes. Acetyl salicylic acid (aspirin), which is currently recommended for cardiovascular disease (CVD) or even CVD risk
factors, is shown to ameliorate diabetic process. This work aimed to study correlation between homeostasis model assessment estimate ofinsulin resistance (HOMA-IR) with serum levels of inflammatory markers tumor necrosis factor α(TNF- α), interleukin 6 (IL-6), C-reactive
protein (CRP), and free fatty acids (FFAs) in experimental model of induced type 2 diabetes in rats, with evaluation of effects of rosiglitazone
and aspirin (low or high dose), alone or in combination. There is significant elevation of insulin resistance and serum levels of fasting
glucose, insulin, TNF- α, IL-6, CRP, and FFAs in the diabetic group when compared to the normal group, with positive significant correlation
between levels of each of TNF- α, IL-6, CRP, and FFAs with insulin resistance (HOMA-IR). Administration of rosiglitazone, low-dose
aspirin, or high-dose aspirin to diabetic rats caused nonsignificant lowering in insulin level with significant reduction of levels of otherparameters when compared to the diabetic group. Also, there is no significant difference in the measured parameters between diabetic ratsadministered a combination of rosiglitazone with high-dose aspirin and those administered a combination of rosiglitazone with low-dose
aspirin. It was concluded that aspirin and rosiglitazone offer unique approaches for treatment of type 2 diabetes due to their insulin-sensitizing
and anti-inflammatory properties, and their combination was found to provide augmented beneficial effects. Also, in view of the potentialdose-dependent adverse effects of aspirin, with no achievement of further benefit by high dose in this study, it is strongly recommended to
use low-dose aspirin as a safe and effective medication for diabetes.
© 2010 Elsevier Inc. All rights reserved.
Keywords: Type 2 diabetes; Rosiglitazone; Aspirin; Insulin resistance; Inflammatory markers
1. Introduction
Both insulin resistance and decreased insulin secretion are
major features of the pathophysiology of type 2 diabetes
(non-insulin-dependent diabetes mellitus) ( Evans, Goldfine,
Maddux, & Grodsky, 2003 ).
Insulin resistance is defined as a decreased response of the
peripheral tissues to insulin action ( Xu et al., 2003 ), and itmost often precedes the onset of hyperglycemia and predictsdevelopment of type 2 diabetes ( Saad et al., 1989; Yki-
Jarvinen, 1994 ).
Several studies left little doubt that inflammatory path-
ways are critical in the mechanisms underlying insulinresistance and type 2 diabetes, resulting in deterioratedmetabolic homeostasis in general and glucose metabolism inparticular ( Wellen & Hotamisligil, 2003 ); where even
minimal disturbances in glucose tolerance are associatedwith a chronic, generalized inflammatory reaction that links
components of the metabolic syndrome and contributes toJournal of Diabetes and Its Complications 24 (2010) 168 –178
WWW.JDCJOURNAL.COM
⁎Corresponding author.
E-mail address: amanynhr@hotmail.com (A.A. Abdin).
1056-8727/09/$ –see front matter © 2010 Elsevier Inc. All rights reserved.
doi:10.1016/j.jdiacomp.2009.01.005

the development of diabetic complications (Lobner &
Fuchtenbusch, 2004 ).
Mechanisms, linking inflammation to insulin resistance,
are being explored; and progress has been made in thisdirection ( Garg, Tripathy, & Dandona, 2003 ).
Recently, there has been increasing interest in the active
role of adipose tissue in the regulation of metabolism(Pankow et al., 2004 ).
In this context, adipocytes and macrophages (that is
derived from preadipocytes or accumulated directly) areknown to secrete inflammatory cytokines [including tumornecrosis factor α(TNF- α), interleukin 6 (IL-6), C-reactive
protein (CRP)], as well as free fatty acids (FFAs), most of
which have been implicated to play important roles in the
cascade of inflammation, systemic insulin resistance,decreased β-cell secretion of insulin, and thus type 2
diabetes ( Bastard et al., 2000; Lobner & Fuchtenbusch,
2004; Pankow et al., 2004 ).
These inflammatory markers have been proposed to be
nontraditional risk factors for cardiovascular disease (CVD)in patients with type 2 diabetes mellitus ( Haffner et al., 2002 ).As a consequence, insulin signaling in adipocytes could
become increasingly impaired, eventually leading to massiveadipocyte lipolysis, necrosis, and systemic insulin resistance(Xu et al., 2003 ). Increased lipolysis is one possible piece of
the puzzle and could in turn result in the release of a large
amount of FFAs, and an increased FFA level in the
circulation has been shown to result in resistance to insulinsignaling in skeletal muscle and liver ( Xu et al., 2003 ).
Thus, the development of drugs targeted to reverse insulin
resistance is an important issue ( Yki-Jarvinen, 2004 ).
The novel class of drugs, thiazolidinediones (e.g.,
rosiglitazone), which are selective synthetic ligands of thenuclear transcription factor peroxisome proliferator-acti-
vated receptor γ(PPAR- γ), act primarily as insulin
sensitizers. They are discovered to have anti-inflammatory
effects leading to the reevaluation of their potential use in thetreatment of diabetes, which may be of considerable clinicalsignificance during long-term therapy ( Diamant & Heine,
2003; Garg et al., 2003; Pershadsingh, 2004 ).
Patients with type 2 diabetes mellitus have a markedly
increased risk of cardiovascular complications, where insulin
Table 1
Values of HOMA-IR and serum levels of TNF- α, IL-6, CRP, FFAs, fasting glucose, and insulin in the studied groups
Parameter Group I n=10 Group II n=7 Group III n=9 Group IV n=8 Group V n=8 Group VI n=10 Group VII n=10
TNF-α(pg/ml) 29.5±2.9 52.7±4.9 45.3±4.2 40.1±3.1 38.7±2.3 34.4±2.4 33.7±2.7
Pb.001aPb.01bPb.001bPb.001bPb.001bPb.001b
NSdPb.001cPb.001c
NSe
IL-6 (pg/ml) 37.4±2.3 45.9±3.9 40.3±3.5 39.5±3.1 38.7±2.7 36.9±2.9 36.7±2.5
Pb.001aPb.05bPb.01bPb.01bPb.001bPb.001b
NSdPb.05cPb.05c
NSe
CRP (mg/dl) 7.9±1.3 12.4±1.9 9.5±1.1 9.1±2.0 8.7±2.3 8.2±1.4 8.1±1.7
Pb.001aPb.01bPb.01bPb.01bPb.001bPb.001b
NSdPb.05cPb.05c
NSe
FFAs (mmol/l) 0.35±0.16 0.84±0.28 0.57±0.17 0.49±0.20 0.52±0.19 0.39±0.14 0.40±0.15
Pb.001aPb.05bPb.05bPb.05bPb.01bPb.01b
NSdPb.05cPb.05c
NSe
Fasting glucose (mmol/l) 4.84±0.83 8.58±1.35 6.75±1.02 7.05±1.54 7.56±1.16 5.25±0.94 5.48±0.97
Pb.001aPb.01bPb.01bPb.01bPb.001bPb.001b
NSdPb.01cPb.05c
NSe
Insulin ( μU/ml) 12.13±1.52 14.21±1.71 13.13±1.26 13.82±1.08 13.45±1.51 12.56±1.12 12.48±1.43
Pb.05aNSbNSbNSbPb.05bPb.05b
NSdNScNSc
NSe
HOMA-IR 2.61±0.15 5.42±0.28 3.94±0.20 4.33±0.19 4.51±0.22 2.93±0.19 3.04±0.21
Pb.001aPb.001bPb.001bPb.001bPb.001bPb.001b
NSdPb.001cPb.001c
NSe
Values are presented as mean±S.D. Pb.05 (significant); Pb.01 or Pb.001 (highly significant). NS, nonsignificant.
aGroup II (diabetic) compared to group I (control).
bGroup III (diabetic with rosiglitazone), Group IV (diabetic with low-dose aspirin), Group V (diabetic with high-dose aspirin), Group VI (diabetic with
both rosiglitazone and low-dose aspirin), Group VII (diabetic with both rosiglitazone and high-dose aspirin) compared to Group II (diabetic).
cGroup VI (diabetic with both rosiglitazone and low-dose aspirin) and Group VII (diabetic with both rosiglitazone and high-dose aspirin) compared to
Group III (diabetic with rosiglitazone).
dGroup V (diabetic with high-dose aspirin) compared to Group IV (diabetic with low-dose aspirin).
eGroup VII (diabetic with both rosiglitazone and high-dose aspirin) compared to Group VI (diabetic with both rosiglitazone and low-dose aspirin).169 A.A. Abdin et al. / Journal of Diabetes and Its Complications 24 (2010) 168 –178

resistance is a major determinant of this increased risk and is
a potential therapeutic target ( Jayagopal, Kilpatrick, Jen-
nings, Hepburn, & Atkkin, 2003 ).
Aspirin, which is currently recommended for patients
who have CVD or even CVD risk factors, is shown to
ameliorate the diabetic process ( Rolka, Fagot-Campagna,
Narayan, 2001; Thomas, Nadackal, & Thomas, 2003 ).
Recent studies demonstrated that salicylates (including
aspirin) can reverse hyperglycemia, hyperinsulinemia, and
dyslipidemia by sensitizing insulin signaling and improve-ment of insulin resistance ( Jiang, Dallas-Yang, Liu, Moller,
& Zhang, 2003; Yin, Yamamoro, & Gaynon, 1998; Yuanet al., 2001 ).
The cellular and molecular mechanism of the hypogly-
cemic activity of aspirin has not been well elucidated ( Gao,
Zuberi, Quon, Dong, & Ye, 2003 ).
The aim of this work is to study the correlation
between insulin resistance and levels of some inflamma-tory markers (namely, TNF- α, IL-6, CRP) and FFAs in
experimental model of induced type 2 diabetes in rats,with evaluation of the effects of rosiglitazone and aspirin
(low or high dose), either alone or in combination on the
levels of these parameters.
2. Materials and methods
This work was completed on 62 albino rats weighing
150–200 g, served in seven groups as following:
Group I: 10 rats served as normal control group, allowed
for ad libitum conventional chow (60% carbohydrate,22% protein, 10% fat, 8% fiber).Group II: 7 rats were rendered as model of type 2 diabetes(Zhang et al., 2003 ), induced experimentally by single
intraperitoneal injection of streptozotocin (STZ, Sigma)15 mg/kg after ad libitum high-fat diet for 2 months (50%carbohydrate, 13% protein, 30% fat, 7% fiber).
This model was designed to mimic the picture of type 2
diabetes in human, where the high-fat diet initiated a state of
insulin resistance and then the addition of the relatively lowdose of STZ established only a relative insulin deficiency
(Zhang et al., 2003 ).In Groups III, IV, V, VI, and VII, the rats were rendered
diabetic as described before and concomitantly treated byoral gavage as follows:
Group III: nine diabetic rats received rosiglitazone (10
mg/kg, po, daily) ( Pickavance, Tadayyon, Widdowson,
Buckingham, & Wilding, 1999 ).
Group IV: eight diabetic rats received low-dose acetyl
salicylic acid (10 mg/kg, po, daily) ( Patumraj et al.,
2000 ).
Group V: eight diabetic rats received high-dose acetylsalicylic acid (120 mg/kg, po, daily) ( Yuan et al., 2001 ).
Group VI: 10 diabetic rats received both rosiglitazone and
low-dose acetyl salicylic acid.
Group VII: 10 diabetic rats received both rosiglitazoneand high-dose acetyl salicylic acid.
At the end of the work (2 days after STZ injection), serum
samples were obtained to measure levels of TNF- α(pg/ml)
and IL-6 (pg/ml) ( Zhang, Yu, Huang, Chen, & Wang, 2004 );
and CRP (mg/dl) ( Modzelewski & Janiak, 2004 ), using the
commercially available rat ELISA kits.
FFAs (mmol/l) levels were measured spectrophotome-
terically by enzymatic colorimetric method, where diphe-
nylcarbazide containing diphenylcarbazone is used as thecolored developing reagent ( Itaya, 1977 ).
Because abnormalities in insulin action are poorly
detected by a single determination of either glucose orinsulin levels ( Laakso, 1993 and American Diabetic
Association, 1998 ), the insulin resistance was evaluated by
homeostasis model assessment estimate of insulin resistance(HOMA-IR) ( Haffner et al., 2002 ) as follows:
Fasting insulin level AU=ml ðȚ /C2 Fasting glucose level mmol =l ðȚ
22:5
Fasting insulin level ( μU/ml) was measured using
commercial RIA kits ( Reaves, 1983 ), and fasting glucose
level (mmol/l) was measured spectrophotometerically byenzymatic colorimetric method ( Bdarham & Trinder, 1972 ).
2.1. Statistics
The values of the measured parameters were presented as
mean±S.D. with calculation of the percentage change in their
Table 2
Percentage change (%) in HOMA-IR and serum levels of TNF- α, IL-6, CRP, and FFAs in different groups
Parameter Group IIan=7 Group IIIbn=9 Group IVbn=8 Group Vbn=8 Group VIbn=10 Group VIIbn=10
TNF-α ↑79% ↓14% ↓24% ↓27% ↓35% ↓36%
IL-6 ↑23% ↓12% ↓14% ↓16% ↓20% ↓20%
CRP ↑57% ↓23% ↓27% ↓30% ↓34% ↓35%
FFAs ↑140% ↓32% ↓42% ↓38% ↓54% ↓52%
HOMA-IR ↑108% ↓27% ↓20% ↓17% ↓46% ↓44%
↑, increase; ↓, decrease.
aPercentage change of Group II from Group I (control).
bPercentage change of Group II, IV, V, VI, and VII, respectively, from group II.170 A.A. Abdin et al. / Journal of Diabetes and Its Complications 24 (2010) 168 –178

levels. The difference between each two groups was
determined using Student's ttest. The correlation between
insulin resistance (HOMA-IR) and each of the inflammatory
markers (TNF- α, IL-6, CRP, and FFAs) was evaluated using
Pearson correlation coefficient. Pvalues were expressed as
Pb.05 (significant), Pb.01, or Pb.001 (highly significant).
All the statistical analyses were processed using Statistical
Program of Social Sciences for windows, version 8.0.
3. Results
Table 1 shows values of HOMA-IR and serum levels of
TNF-α, IL-6, CRP, FFAs, fasting glucose, and insulin of the
all studied groups.
The percentage changes in HOMA-IR and serum levels of
TNF-α, IL-6, CRP, and FFAs are shown in Table 2.The values of the measured parameters of the studied
groups are illustrated as follows: HOMA-IR, Fig. 1; TNF- α,
Fig. 2 ; IL-6, Fig. 3 ; CRP, Fig. 4 ; and FFAs, Fig. 5 .
(1) The results of the present work showed development
of insulin resistance in the diabetic group, which is
expressed as a significant increase in HOMA-IRwhen compared to the control group (5.42±0.28 vs.2.61±0.15; Pb.001).
(2) When compared to the normal control group, the
diabetic group showed significant increase in serum
levels of TNF- α(52.7±4.9 vs. 29.5±2.9; Pb.001), IL-6
(45.9±3.9vs.37.4±2.3; Pb.001),CRP(12.4±1.9vs.7.9±
1.3;Pb.001), FFAs (0.84±0.28 vs. 0.35±0.16; Pb.001),
fasting glucose (8.58±1.35 vs. 4.84±0.83; Pb.001), and
insulin (14.21±1.71 vs. 12.13±1.52; Pb.05).
There is significant positive correlation of the studied
parameters with HOMA-IR as follows: TNF- α,
Fig. 1. Values of HOMA-IR in the studied groups.
Fig. 2. Values of TNF- αin the studied groups.
Fig. 3. Values of IL-6 in the studied groups.
Fig. 4. Values of CRP in the studied groups.171 A.A. Abdin et al. / Journal of Diabetes and Its Complications 24 (2010) 168 –178

r=.870, Pb.05 (Fig. 6 ); IL-6, r=.952, Pb.01 (Fig. 7 );
CRP, r=.919, Pb.01 ( Fig. 8 ); FFAs, r=.982, Pb.001
(Fig. 9 ), respectively.
(3) The diabetic rats with concomitant administration of
rosiglitazone showed significant reduction of the
following studied parameters when compared to thediabetic untreated group: HOMA-IR (3.94±0.20 vs.5.42±0.28, Pb.001), TNF- α(45.3±4.2 vs. 52.7±4.9,
Pb.01), IL-6 (40.3±3.5 vs. 45.9±3.9, Pb.05), CRP
(9.5±1.1 vs. 12.4±1.9, Pb.01), FFAs (0.57±0.17 vs.
0.84±0.28, Pb.05), and fasting glucose (6.75±1.02 vs.
8.58±1.35, Pb.01), respectively. However, there is
nonsignificant change in insulin level (13.13±1.26 vs.14.21±1.71).
(4) The diabetic rats administered with low-dose acetyl
salicylic acid showed significant reduction of thefollowing studied parameters when compared to thediabetic untreated group: HOMA-IR (4.33±0.19 vs.
5.42±0.28, Pb.001), TNF- α(40.1±3.1 vs. 52.7±4.9,
Pb.001), IL-6 (39.5±3.1 vs. 45.9±3.9, Pb.01), CRP
(9.1±2.0 vs. 12.4±1.9, Pb.01), FFAs (0.49±0.20 vs.0.84±0.28, Pb.05), and fasting glucose (7.05±1.54 vs.
8.58±1.35, Pb.01), respectively. The change in insulin
level is nonsignificant (13.82±1.08 vs. 14.21±1.71).
(5) Administration of high-dose acetyl salicylic acid to
the diabetic group caused significant reduction of thefollowing studied parameters when compared to the
diabetic untreated group: HOMA-IR (4.52±0.22 vs.5.42±0.28, Pb.001), TNF- α(38.7±2.3 vs. 52.7±4.9,
Pb.001), IL-6 (38.8±2.7 vs. 45.9±3.9, Pb.01), (CRP
8.7±2.3 vs. 12.4±1.9, Pb.01), FFAs (0.52±0.19 vs.
0.84±0.28, Pb.05),
and fasting glucose (7.56±1.16 vs.
8.58±1.35, Pb.01), respectively. The change in insulin
level is nonsignificant (13.45±1.51 vs. 14.21±1.71).
(6) The diabetic rats that received the combination of
rosiglitazone with low-dose acetyl salicylic acidshowed significant reduction of the following studiedparameters when compared to the untreated diabeticgroup: HOMA-IR (2.93±0.19 vs. 5.42±0.28, Pb.001),
TNF-α(34.4±2.4 vs. 52.7±4.9, Pb.001), IL-(6 36.9±
2.9 vs. 45.9±3.9, Pb.001), CRP (8.2±1.4 vs. 12.4±
1.9, Pb.001), FFAs (0.39±0.14 vs. 0.84±0.28,
Pb.01), fasting glucose (5.25±0.94 vs. 8.58±1.35,
Pb.001), and insulin (12.56±1.12 vs. 14.21±1.71,
Pb.05), respectively.
Fig. 5. Values of FFAs in the studied groups.
Fig. 7. Correlation between IL-6 and HOMA-IR in the diabetic group.
Fig. 8. Correlation between CRP and HOMA-IR in the diabetic group.
Fig. 6. Correlation between TNF- αand HOMA-IR in the diabetic group.172 A.A. Abdin et al. / Journal of Diabetes and Its Complications 24 (2010) 168 –178

(7) The diabetic rats that received the combination of
rosiglitazone with high-dose acetyl salicylic acid
showed significant reduction of the following studiedparameters when compared to the untreated diabeticgroup: HOMA-IR (3.04±0.21 vs. 5.42±0.28, Pb.001),
TNF-α(37.7±2.7 vs. 52.7±4.9, Pb.001), IL-6 (36.7±
2.5 vs. 45.9±3.9, Pb.001), CRP (8.1±1.7 vs. 12.4±1.9,
Pb.001), FFAs (0.41±0.15 vs. 0.84±0.28, Pb.01),
fasting glucose (5.48±0.97 vs. 8.58±1.35, Pb.001),
and insulin (12.48±1.43 vs. 14.21±1.71, Pb.05),
respectively.
(8) When compared to the diabetic rats that received
rosiglitazone alone, the diabetic rats that received thecombination of rosiglitazone with low-dose acetyl
salicylic acid showed significant augmented reduc-
tion of the following studied parameters: HOMA-IR(2.93±0.19 vs. 3.94±0.20, Pb.001), TNF- α(34.4±
2.4 vs. 45.3±4.2, Pb.001), IL-6 (36.9±2.9 vs. 40.3±
3.5,Pb.05), CRP (8.2±1.4 vs. 9.5±1.1, Pb.05), FFAs
(0.39±0.14 vs. 0.57±0.17, Pb.05), and fasting
glucose (5.25±0.94 vs. 6.75±1.02, Pb.01), respec-
tively. However, there is nonsignificant change in
insulin level (12.56±1.12 vs. 13.13±1.26).
(9) Also, when compared to the diabetic rats that
received rosiglitazone alone, the diabetic rats that
received the combination of rosiglitazone with high-dose acetyl salicylic acid showed significant aug-mented reduction of the following studied para-meters: HOMA-IR (3.04±0.21 vs. 3.94±0.20,Pb.001), TNF- α(33.7±2.7 vs. 45.3±4.2, Pb.001),
IL-6 (36.7±2.5 vs. 40.3±3.5, Pb.05), CRP (8.1±1.7
vs. 9.5±1.1, Pb.05), FFAs (0.41±0.15 vs. 0.57±0.17,
Pb.05), and fasting glucose (5.48±0.97 vs. 6.75±
1.02, Pb.05), respectively. However, there is non-
significant change in insulin level (12.48±1.43 vs.13.13±1.26).
(10) There is nonsignificant difference in all studied
parameters between the diabetic rats that received
high-dose acetyl salicylic acid and those that received
low-dose acetyl salicylic acid (HOMA-IR, 4.52±0.22vs. 4.33±0.19; TNF- α, 38.7±2.3 vs. 40.1±3.1; IL-6,38.8±2.7 vs. 39.5±3.1; CRP, 8.7±2.3 vs. 9.1±2.0;FFAs, 0.52±0.19 vs. 0.49±0.20; fasting glucose,7.56±1.16 vs. 7.05±1.54; insulin, 13.45±1.1.51 vs.13.82±1.08, respectively).
(11) Also, there is nonsignificant difference in all
studied parameters between the diabetic rats thatreceived rosiglitazone and high-dose acetyl sal-icylic acid and those that received rosiglitazonewith low-dose acetyl salicylic acid (HOMA-IR,3.04±0.21 vs. 2.93±0.19; TNF- α, 33.7±2.7 vs.
34.4±2.4; IL-6, 36.7±2.5 vs. 36.9±2.9; CRP, 8.1±1.8 vs. 8.2±1.4; FFAs, 0.41±0.15 vs. 0.39±0.14;fasting glucose, 5.48±0.97 vs. 5.25±0.94; insulin,
12.48±1.43 vs. 12.56±1.12, respectively).
4. Discussion
According to the new classification and diagnostic criteria
fordiabet
es proposed by the American Diabetes Association,
the development of type 2 diabetes is linked to insulinresistance (impaired insulin sensitivity) coupled with a
failure of pancreatic cells to compensate by adequate insulinsecretion ( Fujimoto, 2000 and Gabir et al., 2002 ).
In the present work, the group of induced type 2
diabetes showed significant increase in serum levels ofglucose, insulin, and HOMA-IR value when compared tothe normal control group, which indicates development ofinsulin resistance.
Several studies documented that insulin resistance most
often precedes the onset of overt type 2 diabetes and iscompensated initially by hyperinsulinemia ( Evans et al.,
2003 and Zhang et al., 2003 ). This hyperinsulinemia is
produced by both compensatory insulin hypersecretion andby reduced hepatic extraction of insulin ( Polonsky et al.,
1988 ). But this chronic secretion of large amounts of insulin
to overcome tissue insensitivity can itself finally lead to
pancreatic beta cell failure and occurrence of hyperglycemia
(Yuan et al., 2001 ).
It is needed to know the temporal relationship of changes
in circulating proinflammatory cytokines, acute-phase mar-kers, insulin resistance, and glycemia during the develop-ment of type 2 diabetes. This will raise the question ofwhether these would be helpful in screening programsidentifying individuals at risk of diabetes, and if drugs with
anti-inflammatory properties can contribute to the manage-
ment of the disease ( Pickup, 2004 ).
The results of the present work showed significant
increased levels of each of TNF- α, IL-6, and CRP, which
are in significant positive correlation with insulin resistance(HOMA-IR) in the diabetic untreated rats.
This is in agreement with the finding of an association
between high plasma levels of TNF- α(Nilsson, Jovinge,
Neimann, Reneland, & Lithell, 1998 )I L – 6( Ridker, Henne-
kins, Buring, & Rifai, 2000 ) with insulin resistance and type
2 diabetes.
Fig. 9. Correlation between FFAs and HOMA-IR in the diabetic group.173 A.A. Abdin et al. / Journal of Diabetes and Its Complications 24 (2010) 168 –178

Also, Leinonen et al. (2003) estimated that all markers of
inflammation (including IL-6 and CRP) were positively
correlated with HOMA-IR.
Growing evidence has pointed to a correlative and
causative relationship between inflammation and insulin
resistance/type2 diabetes mellitus ( Xu et al., 2003 ).
These circulating markers of inflammation (e.g., TNF- α
and IL-6) and acute-phase reactants (e.g., CRP) are
considered strong predictors of the development of type 2diabetes and the possible associated cardiovascular compli-cations ( Pickup, 2004 ).
In this context, Temelkova-Kurktschiev et al. (2002)
reported that the inflammatory markers were related to
insulin resistance but not to insulin secretion.
Recent data have revealed that the plasma concentration of
inflammatory mediators, such as TNF- αand IL-6, is increased
in the insulin resistant states of obesity and type 2 diabetes.
They interfere with insulin action by suppressing insulinsignal transduction, and this might interfere with the anti-inflammatory effect of insulin, which in turn might promoteinflammation ( Dandona, Aljada, & Bandyopadhyay, 2004 ).
Several researches reported that the circulating TNF- αis
usually elevated in established type 2 diabetes ( Katsuki et al.,
1998; Pickup, Chusney, Thomas, & Burt, 2000; Winkler,Salamon, Speer, Simon, & Cseh, 1998 ).
Regarding IL-6 and CRP, there are contradictory results
obtained by Richardson and Tayek (2002) that their plasma
levels did not reach the statistical significant values.However, they explained that this may be due to the small
number of subjects and that an ultrasensitive assay is
required for accurate measurement of circulating concentra-tions of IL-6 and CRP.
Also, a controversial result obtained by Bastard et al.
(2000) showed that there is nonsignificant correlation
between TNF- αand insulin resistance. But this may be
attributed to the fact that the correlation was performedcollectively for the whole used groups (obese nondiabetic
and diabetic) in their study and not to the diabetic group only.
The data presented by Senn, Klover, Nowak, and Mooney
(2002) showed that IL-6 plays a direct role in insulin
resistance at the cellular level by inhibiting insulin receptor
signal transduction and insulin metabolic actions includinginhibition of insulin-induced glycogen synthesis.
Regarding TNF- α, it has been reported to inhibit insulin-
induced glucose uptake by targeting more than one
component of insulin signaling cascade including, insulin
receptor, insulin receptor substrate (IRS), and glucosetransporter 4. The mechanism of these effects is proved tobe due to stimulation of serine phosphorylation of IRS [viaactivity of the serine kinase inhibitor of nuclear factor- κβ
kinase (IKK- β)] leading to both degradation of IRS and
inhibition of tyrosine phosphorylation which is essential forinsulin signaling and action ( Gao et al., 2003 ).
In addition, the inflammatory cytokines such as TNF- α
and IL-6 were reported to down-regulate PPAR- γexpression
(Tanaka et al., 1999 ).It is known that PPAR- γis expressed abundantly in
adipose tissue, pancreatic beta cells, and macrophages,where it regulates gene transcription of various adipokines,possesses anti-inflammatory activity, and control fatty aciduptake and storage ( Yki-Jarvinen, 2004 ).
In the diabetic group, the elevated FFA level with
significant positive correlation with HOMA-IR obtainedin this work is in agreement with that estimated in manyprevious studies ( Baldeweg et al., 2000; Laws et al.,
1997; Lewis et al., 1991; Reaven, Hollenbeck, Jeng, Wu,& Chen, 1988 ).
In a study by Pankow et al. (2004) , there is no significant
association found between FFAs and HOMA-IR. The lack of
correlation between increased FFAs and HOMA-IR may be
attributed to the fact that FFAs stimulate insulin secretion andsome of this insulin is transmitted in the peripheralcirculation and is able to compensate for FFA-mediatedperipheral insulin resistance ( Boden, 1997 ).
Several mechanisms of how elevated FFA levels decrease
insulin sensitivity have been proposed, including the Randlehypothesis concerning inhibition of insulin-stimulated
glucose transport. It also should be noted that FFAs regulate
gene expression, especially those involved in lipid andcarbohydrate metabolism ( Evans et al., 2003 ).
ChronicallyelevatedFFAsmayalsoimpairinsulinsecretory
function through toxic effects on pancreatic beta cells aspredicted by the “lipotoxic ity
hypothesis ”(Unger, 1995 ).
Finally, increased flux of FFAs from adipose tissue due to
lipolysis of visceral adipose depots (triglycerides) to the
nonadipose tissue (e.g., liver, skeletal muscle) may lead to
excessive endogenous glucose production and progression tofrank type 2 diabetes ( Rebrin et al., 1995 and Lewis,
Carpentier, Adeli, & Giacca, 2002 ).
Because insulin resistance both precedes and predicts
type 2 diabetes, thus, development of drugs targeted toreverse it is an important issue ( Yki-Jarvinen, 2004 ).
Also, due to link between insulin resistance and inflam-
matory process, it is suggested that the therapeutic strategiesthat limit inflammation and reduce levels of inflammatorymarkers may be a promising tool ( Marx et al., 2003 ).
The insulin sensitizer thiazolidinediones is the first drug
to address the basic problem of insulin resistance in type 2diabetes ( Yki-Jarvinen, 2004 ).
The results of the present work showed that rosiglitazone
significantly reduced insulin resistance (HOMA-IR) and
glucose level, with nonsignificant decrease in insulin level,
which supposed that the improvement in glycemic control isattributed to mechanisms that involve insulin action ratherthan insulin secretion.
It has been hypothesized that the insulin-sensitizing
effects of thiazolidinediones may occur at least in partthrough decreased lipolysis of adipose tissue and subsequentreduction in circulating FFAs ( Mora & Pessin, 2002 ).
Lewis et al. (2002) reported that PPAR- γactivators
(thiazolidinediones), which overcome insulin resistance ofadipose tissue by improving adipocyte FFA esterification,174 A.A. Abdin et al. / Journal of Diabetes and Its Complications 24 (2010) 168 –178

are postulated to be more effective in reducing the
deleterious metabolic effects of fat dysregulation.
Recent experimental data suggest that thiazolidinediones
(TZDs, glitazones), in addition to their metabolic effects,exhibit anti-inflammatory properties ( Marx et al., 2003 and
Mohanty et al., 2004 ).
Yki-Jarvinen (2004) documented that thiazolidinediones
exert their insulin-sensitizing actions either (1) directly, bypromoting fatty acid uptake and storage in adipose tissuewhile sparing other insulin-sensitive tissues (mainly skeletalmuscle and liver, and possibly pancreatic beta cells) from theharmful metabolic effects of high concentrations of FFAs(the“fatty acid steal ”hypothesis), or (2) indirectly, by means
of altered adipocytokine release.
The results of the present work showed that rosiglitazone
significantly reduced levels of the inflammatory markers andFFAs in the diabetic rats.
Pickup (2004) stated that although the chronic hypergly-
cemia is not sufficient to induce inflammation, it maycontribute to it. So, the improvement in glycemic controlmay therefore reduce the inflammatory response.
It was established that the decrease in blood glucose level
in type 2 diabetes is accompanied with reduced levels ofinflammatory markers ( Arnalich et al., 2000 and Yoo &
Desiderio, 2003 ).
The results of the present work are in agreement with that
reported by Miyazaki et al. (2001) that rosiglitazone
consistently lowers FFA concentrations in clinical studies.This is confirmed by other recent researches by Goldstein,
Cobitz, Hand, and Chen (2003) and Chen et al. (2004) who
proved that rosiglitazone significantly reduced FFA levelconcomitantly with improvement of insulin resistance(HOMA-IR). Meriden (2004) reviewed that rosiglitazone
was reported to significantly reduce levels of CRP and FFAsin diabetic cases.
In a study by Haffner et al. (2002) , rosiglitazone was
shown to improve HOMA-IR and reduce CRP but without
significant reduction of IL-6 level. They explained that
rosiglitazone treatment has been associated with increase insubcutaneous fat, which is a significant source of IL-6expression.
In addition, Gee et al. (2004) obtained results of an overall
improvement in insulin regulation and lipid profile, althoughno significant differences were noted in levels of TNF- αand
CRP during the treatment period with rosiglitazone. To
explain such conflict, Spranger et al. (2003) emphasized that
the pathogenesis of type 2 diabetes depends on the
combination pattern of inflammatory cytokines rather thanon a single cytokine, and they proved that the elevated levelsof IL-6 or TNF- αalone are not independently associated
with risk of type 2 diabetes.
As reviewed by Nowak and Jaber (2003) , the evidences
do not support a particular dose of aspirin to be
recommended for cardiovascular protection in diabetic
patients. The dose of aspirin may be different from that forother populations and requires further evaluation.For this reason, low and high doses of acetyl salicylic acid
were used in the present research to revaluate their effects onglycemic control and inflammatory markers.
The present work showed significant lowering effects on
the degree of insulin resistance, levels of the inflammatory
markers, and FFAs in the diabetic rats by either low or high
dose of aspirin.
Several different clinical studies including in vitro ( Gao
et al., 2003 and Jiang et al., 2003 ), in vivo with high doses
(6.2 g/day, Hundal et al., 2002 ; 120 mg/kg per day, Yuan
et al., 2001 ; 1 g t.d.s/day, Mata-Segreda, Fernandez-
Azofeifa, Madrigal, & Morales, 1989 ), and in vivo with
low doses (100 mg/day, Contreras et al., 1997 ) established
that acetyl salicylic acid improved insulin resistance withdecrease in glucose concentrations and reduction ofinflammatory markers including CRP.
The present work showed that administration of aspirin
either in low dose or high dose to the diabetic rats resulted insignificant lowering of both insulin resistance (HOMA-IR)and glucose level without nonsignificant effect on insulinlevel, suggesting that aspirin ameliorates glycemic control by
insulin-sensitizing effects.
Previously, Giugliano et al. (1985) suggested that the
acute insulinotropic effect of acetylsalicylate infusion was
due to inhibition of endogenous prostaglandin E (PGE)synthesis, and the concurrent infusion of PGE
2abolished this
effect. But this study focused on the acute effect ofacetylsalicylate on insulin secretion but not the tissuesensitivity to this insulin on long-term use.
More recent studies ( Colwell, 2001; Gao et al., 2003;
Hundal et al., 2002; Jiang et al., 2003 ) proposed several
possible mechanisms to mediate the insulin-sensitizingeffect of aspirin. First, the molecular events proved theability of salicylates to inhibit IRS-1 serine phosphoryla-tion, which is strongly implicated in development of insulinresistance, by targeting the serine kinases (e.g., IKK- β).
Second, the insulin-sensitizing effect may be attributed to
its direct antilipolytic action leading to reduction of the rate
of lipolysis and lowering FFA levels. Third, salicylateswere proved to decrease insulin clearance and hepaticglucose production. Finally, salicylates were shown tosignificantly reduce the inflammatory markers (CRP) eitherby low or high dose, where an anti-inflammatory mechan-ism was suggested.
Contradictory results were obtained in a previous study
byBratusch-Marrain, Vierhapper, Komjati, and Waldhausl
(1985) that showed that administration of acetyl salicylic
acid (aspirin) to type 2 diabetic patients (3 g/day for 3days) caused impairment of tissue sensitivity to insulinduring a hyperglycemic clamp study. However, on theother hand, there was decrease in fasting hyperglycemiathat was explained by the enhancement of plasma responseto insulin.
The results of the present work showed nonsignificant
difference between low and high doses of aspirin whenadministered to the diabetic rats.175 A.A. Abdin et al. / Journal of Diabetes and Its Complications 24 (2010) 168 –178

Eccles, Freemantle, and Mason (1998) reviewed the
guidelines on use of aspirin and reported that the trials have
used different doses of aspirin for protection and treatment ofCVDs with no evidence that aspirin in doses more than75 mg daily provides greater benefit.
Although each of rosiglitazone and aspirin is currently
prescribed alone or in combination for type 2 diabetesmellitus, but there is no available coherent information aboutthe effect of their combination on insulin resistance,inflammatory markers and FFAs.
In the present work, the groups administered the
combination of rosiglitazone and aspirin (either in low orhigh dose) showed significant decrease in insulin resis-
tance, levels of circulating inflammatory markers, fasting
glucose, insulin, and FFAs when compared to the diabeticuntreated group.
This significant decrease in insulin level associated with
significant improvement of insulin resistance denotes goodglycemic control by such combination and is in agreementwith the fact that insulin level always reflects changes ininsulin sensitivity, where there is compensatory hyperinsu-
linemia in response to insulin resistance, and vice versa, the
insulin level decreased when insulin resistance is improved(Cook & Taborsky, 1996 ).
When the groups administered the combination of
rosiglitazone and aspirin (either in low or high dose) werecompared to that administered rosiglitazone alone, there issignificant augmented decrease in insulin resistance, levelsof circulating inflammatory markers, fasting glucose, and
FFAs. These results are in context with the previously
discussed results of the present work, which proved thateither rosiglitazone or aspirin (at low or high dose) canindividually reduce insulin resistance and decrease levels ofinflammatory markers and FFAs.
4.1. Conclusion
Insulin resistance forms a hallmark of type 2 diabetes
mellitus and is a major determinant of its cardiovascular
complications, where the inflammatory pathways play animportant role. Therefore, diabetes therapy should focus onthis underlying mechanism to provide glycemic control anddecrease risk of cardiovascular complications.
Aspirin and rosiglitazone offer unique approaches for
the treatment of type 2 diabetes due to their insulin-
sensitizing and anti-inflammatory properties. Their combi-
nation was found to produce augmented beneficial effectswhen compared to rosiglitazone alone, providing goodglycemic control and consequently decrease risk ofcardiovascular complications.
In view of the potential dose-dependent adverse effects of
aspirin, with no further benefit achieved by high doses, it isstrongly recommended to use low-dose aspirin as a safe and
effective medication for diabetes.
In the future, inhibition of the serine kinase IKK- β
pathway by aspirin may provide a promising valuable targetfor discovery of other new drugs for treatment of type 2
diabetes, which needs further researches and evaluation.
References
American Diabetic Association. (1998). Consensus development conference
on insulin resistance: 5 –6 November 1997. Diabetes Care ,21,
310−314.
Arnalich, F., Hernanz, A., Lopez-Maderuelo, D., Camacho, J., Madero, R.,
Vazquez, J. J., & Montiel, C. (2000). Enhanced acute-phase response
and oxidative stress in older adults with type II diabetes. Hormone and
Metabolic Research ,32, 407−412.
Baldeweg, S. E., Golay, A., Natali, A., Balkau, B., Del Prato, S., & Coppack,
S. W. (2000). Insulin resistance, lipid and fatty acid concentrations in867 healthy Europeans. European Journal of Clinical Investigation ,30,
45−52.
Bastard, J. P., Jardel, C., Bruckert, E., Blondy, P., Capeau, J., Laville, M.,
Vidal, H., & Hainque, B. (2000). Elevated levels of interleukin 6 arereduced in serum and subcutaneous adipose tissue of obese women afterweight loss. Journal of Clinical Endocrinology and Metabolism ,85(9),
3338−3342.
Bdarham, D., & Trinder, P. (1972). Enzymatic determination of glucose.
Analyst ,97, 142−145.
Boden, G. (1997). Role of fatty acids in the pathogenesis of insulin
resistance and NIDDM. Diabetes ,46(1), 3−10.
Bratusch-Marrain, P. R., Vierhapper, H., Komjati, M., & Waldhausl, W. K.
(1985). Acetyl-salicylic acid impairs insulin-mediated glucose utiliza-
tion and reduces insulin clearance in healthy and non-insulin-dependent
diabetic man. Diabetologia ,28(9), 671 −676.
Chen, X. P., Yang, W. Y., Bu, S., Xiao, J. Z., Liu, X. L., Wang, N., & Zhao,
W. H. (2004). Effects of rosiglitazone and metformin on insulin
resistance in high-fat diet rats. Zhonghua Nei Ke Za Zhi ,43(4),
280−283.
Colwell, J. A. (2001). Aspirin therapy in diabetes is underutilized. Diabetes
Care,24, 195−196.
Contreras, I., Reiser, K. M., Martinez, N., Giansante, E., Lopez, T., Suarez,
N., Postalian, S., Molina, M., Gonzalez, F., Sanchez, M. R., Camejo, M.,
& Blanco, M. C. (1997). Effects of aspirin or basic amino acids oncollagen cross-links and complications in NIDDM. Diabetes Care ,20
(5), 832 −835.
Cook, D., & Taborsky, G. J. R. (1996). B-cell function and insulin secretion.
In H. Rifkin, & D. Porte Jr (Eds.), Ellenberg and Rifkin's Diabetes
mellitus, theory and practice (4th edition, pp. 89 −103). Elsevier Science
Publishing Co.
Dandona, P., Aljada, A., & Bandyopadhyay, A. (2004). Inflammation: The
link between insulin resistance, obesity and diabetes. Trends in
Immunolog y,25(1),
4−7.
Diamant, M., & Heine, R. J. (2003). Thiazolidinediones in type 2 diabetes
mellitus: Current clinical evidence. Drugs ,63(13), 1373 −1405.
Eccles, M., Freemantle, N., & Mason, J. (1998). North of England evidence
based guideline development project: Guideline on the use of aspirin assecondary prophylaxis for vascular disease in primary care. BMJ,316,
1303−1309.
Evans, J. L., Goldfine, I. D., Maddux, B. A., & Grodsky, G. M. (2003). Are
oxidative stress-activated signaling pathways mediators of insulinresistance and β-cell dysfunction? Diabetes ,52,1−8.
Fujimoto, W. Y. (2000). The importance of insulin resistance in the
pathogenesis of type 2 diabetes mellitus. American Journal of Medicine ,
108(suppl), 9 −14.
Gabir, M. M., Hanson, R. L., Debelea, D., Imperatore, G., Roumain, J.,
Bennett, P. H., & Knowler, W. C. (2002). The 1997 American Diabetes
Association and 1999 World Health Organization criteria for hypergly-
cemia in the diagnosis and prediction of diabetes. Diabetes Care ,23,
1108−1112.
Gao, Z., Zuberi, A., Quon, M. J., Dong, Z., & Ye, J. (2003). Aspirin inhibits
serine phosphorylation of insulin receptor substrate 1 in tumor necrosis176 A.A. Abdin et al. / Journal of Diabetes and Its Complications 24 (2010) 168 –178

factor-treated cells through targeting multiple serine kinases. Journal of
Biological Chemistry ,278(27), 24944 −24950.
Garg, R., Tripathy, D., & Dandona, P. S. (2003). Insulin resistance as a
proinflammatory state: Mechanisms, mediators, and therapeutic inter-
ventions. Curr Drug Targets ,4(6), 487 −492.
Gee, M. K., Zhang, L., Rankin, S. E., Collins, J. N., Kauffman, R. F., &
Wanger, J. D. (2004). Rosiglitazone treatment improves insulinregulation and dyslipidemia in type 2 diabetic cynomolgus monkeys.Metabolism ,53(9), 1121 −1125.
Giugliano, D., Ceriello, A., Saccomanno, F., Quatraro, A., Paolisso, G., &
D'Onofrio, F. (1985). Effects of salicylate, tolbutamide, and prostaglan-din E2 on insulin responses to glucose in noninsulin-dependent diabetesmellitus. Journal of Clinical Endocrinology and Metabolism ,61(1),
160−166.
Goldstein, B. J., Cobitz, A. R., Hand, L. M., & Chen, H. (2003). Are the
metabolic effects of rosiglitazone influenced by baseline glycaemiccontrol? Current Medical Research and Opinion ,19(3), 192.
Haffner, S. M., Greenberg, A. S., Weston, W. M., Chen, H., Williams, K., &
Freed, M. I. (2002). Effect of rosiglitazone treatment on nontraditionalmarkers of cardiovascular disease in patients with type 2 diabetesmellitus. Circulation ,106, 679−684.
Hundal, R. S., Petersen, K. F., Mayerson, A. B., Randhawa, P. S., Inzucchi,
S., Shoelson, S. E., & Shulman, G. I. (2002). Mechanism by which highdose aspirin improves glucose metabolism in type 2 diabetes. Journal of
Clinical Investigation ,109, 1321 −1326.
Itaya, K. (1977). Amore sensitive and stable colorimetric determination of
free fatty acids in blood. Journal of Lipid Research ,18, 663−665.
Jayagopal, V., Kilpatrick, E. S., Jennings, P. E., Hepburn, D. A., & Atkin,
S. L. (2003). Biological variation of homeostasis model assessment-derived insulin resistance in type 2 diabetes. Diabetes Care ,25,
2022−2025.
Jiang, G., Dallas-Yang, Q., Liu, F., Moller, D. E., & Zhang, B. B. (2003).
Salicylic acid reverses phorbol 12-myristate-13-acetate (PMA)- andtumor necrosis factor- α(TNF-α ) induced insulin receptor substrate 1
(IRS1) serine 307 phosphorylation and insulin resistance in human
embryonic kidney 293 (HEK293) cells. Journal of Biological Chemistry ,
278(1), 180 −186.
Katsuki, A., Sumida, Y., Murashima, S., Murata, K., Takarada, Y., Ito, K.,
Fujii, M., Tsuchihashi, K., Goto, H., Nakatani, K., & Yano, Y. (1998).Serum levels of tumor necrosis factor- αare increased in obese patients
with noninsulin-dependent diabetes mellitus. Journal of Clinical
Endocrinology and Metabolism ,83, 859−862.
Laakso, M.
(1993). How good a marker is insulin level for insulin
resistance? Am J Epidemiol ,137, 959−965.
Laws, A., Hoen, H. M., Selby, J. V., Saad, M. F., Haffner, S. M., & Howard,
B. V. (1997). Differences in insulin suppression of free fatty acid levelsby gender and glucose tolerance status. Relation to plasma triglyceride
and apolipoprotein B concentrations. Insulin Resistance AtherosclerosisStudy (IRAS) Investigators. Arteriosclerosis, Thrombosis, and Vascular
Biology ,17,6 4−71.
Leinonen, E., Hurt-Camejo, E., Wiklund, O., Hultén, L. M., Hiukka, A., &
Taskinen, M. R. (2003). Insulin resistance and adiposity correlate withacute-phase reaction and soluble cell adhesion molecules in type 2diabetes. Atherosclerosis ,166, 387−394.
Lewis, G. F., Carpentier, A., Adeli, K., & Giacca, A. (2002). Disordered fat
storage and mobilization in the pathogenesis of insulin resistance andtype 2 diabetes. Endocrine Reviews ,23(2), 201 −229.
Lewis, G. F., O'Meara, N. M., Soltys, P. A., Blackman, J. D., Iverius, P. H.,
Pugh, W. L., Getz, G. S., & Polonsky, K. S. (1991). Fastinghypertriglyceridemia in noninsulin-dependent diabetes mellitus is animportant predictor of postprandial lipid and lipoprotein abnormalities.
Journal of Clinical Endocrinology and Metabolism, 72, 934−944.
Lobner K., and Fuchtenbusch M., (2004): Inflammation and diabetes.
MMW Fortschr Med. 146(35-36):32 –3, 35 –6.
Marx, N., Froehlich, J., Siam, L., Ittner, J., Wierse, G., Schmidt, A.,
Scharnagl, H., Hombach, V., & Koenig, W. (2003). Antidiabetic
PPAR γ-activator rosiglitazone reduces MMP-9 serum levels in type 2diabetic patients with coronary artery disease. Arteriosclerosis, Throm-
bosis, and Vascular Biology ,23, 283−288.
Mata-Segreda, J. F., Fernandez-Azofeifa, E., Madrigal, X., & Morales, A. C.
(1989). Clinical evaluation of acetylsalicylic acid to improve glycemia intype II diabetic patients. Acta Physiologica et Pharmacologica
Latinoamericana ,39(1), 9−13.
Meriden, T. (2004). Progress with thiazolidinediones in the management of
type 2 diabetes mellitus. Clinical Therapeutics ,26(2), 177 −190.
Miyazaki, Y., Glass, L., Triplitt, C., Matsuda, M., Cusi, K., Mahankali, A.,
Mahankali, S., Mandarino, L. J., & DeFronzo, R. A. (2001). Effect ofrosiglitazone on glucose and non-esterified fatty acid metabolism in type2 diabetic patients. Diabetologia ,44, 2210 −2219.
Modzelewski, B., & Janiak, A. (2004). Pentoxiyphilline as a cyclooxygen-
ase (cox-2) inhibitor in experimental sepsis. Medical Science Monitor ,
10(7), BR233 −BR237.
Mohanty, P., Aljada, A., Ghanim, H., Hofmeyer, D., Tripathy, D., Syed, T.,
Al-Haddad, W., Dhindsa, S., & Dandona, P. (2004). Evidence for a
potent antiinflammatory effect of rosiglitazone. Journal of Clinical
Endocrinology and
Metabolism ,89(6), 2728 −2735.
Mora, S., & Pessin, J. E. (2002). An adipocentric view of signaling and
intracellular trafficking. Diabetes Metabolism Research and Reviews ,
18, 345−356.
Nilsson, J., Jovinge, S., Neimann, A., Reneland, R., & Lithell, H. (1998).
Relation between tumor necrosis factor- and insulin sensitivity in elderlymen with non-insulin-dependent diabetes mellitus. Arteriosclerosis,
Thrombosis, and Vascular Biology ,18, 1199 −1202.
Nowak, S. N., & Jaber, L. A. (2003). Aspirin dose for prevention of
cardiovascular disease in diabetics. Annals of Pharmacotherapy ,37(1),
116−121.
Pankow, J. S., Duncan, B. B., Schmidt, M. I., Ballantyne, C. M., Couper,
D. J., Hoogeveen, R. C., & Golden, S. H. (2004). Fasting plasma free
fatty acids and risk of type 2 diabetes. Diabetes Care ,27,7 7−82.
Patumraj, S., Tewit, S., Amatyakul, S., Jariyapongskul, A., Maneesri, S.,
Kasantikul, V., & Shepro, D. (2000). Comparative effects of garlic andaspirin on diabetic cardiovascular complications. Drug Delivery ,7(2),
91−96.
Pershadsingh, H. A. (2004). Peroxisome proliferator-activated receptor-
gamma: therapeutic target for diseases beyond diabetes: quo vadis?Expert Opinion on Investigational Drugs ,13(3), 215 −228.
Pickavance, L. C., Tadayyon, M., Widdowson, P. S., Buckingham, R. E., &
Wilding, J. P. (1999). Therapeutic index for rosiglitazone in dietaryobese rats: separation of efficacy and haemodilution. BJP,3(3),
171−180.
Pickup, J. C. (2004). Inflammation and activated innate immunity in the
pathogenesis of type 2 diabetes. Diabetes Care ,27, 813−823.
Pickup, J. C., Chusney, G. C., Thomas, S. M., & Burt, D. (2000). Plasma
interleukin-6, tumor necrosis factor alpha and blood cytokine productionin types 2 diabetes. Life Science ,67, 291−300.
Polonsky, K. S., Given, B. D., Hirsch, L., Shapiro, E. T., Tillil, H., Beebe, C.,
Galloway, J. A., Frank, B. H., Karrison, T., & Van Cauter, E. (1988).
Quantitative study of insulin secretion and clearance in normal and obese
subjects. Journal of Clinical Investigation ,81, 435−441.
Reaven, G. M., Hollenbeck, C., Jeng, C. Y., Wu, M. S., & Chen, Y.D.
(1988). Measurement of plasma glucose, free fatty acid, lactate, and
insulin for 24 h in patients with NIDDM. Diabetes ,37, 1020 −1024.
Reaves, W
. G. (1983). Insulin antibody determination in theoretical and
practical considerations. Diabetologia ,24, 399−403.
Rebrin, K., Steil, G. M., Getty, L., & Bergman, G. M. (1995). Free fatty acid
as a link in the regulation of hepatic glucose output by peripheral insulin.
Diabetes ,44(9), 1038 −1045.
Richardson, A. P., & Tayek, J. A. (2002). Type 2 diabetic patients may have
a mild form of an injury response: a clinical research center study. Am J
Physiol ,282, E1286 −E1290.
Ridker, P. M., Hennekens, C. H., Buring, J. E., & Rifai, N. (2000).
C-reactive protein and other markers of inflammation in the
prediction of cardiovascular disease in women. N Engl J Med ,342,
836−843.177 A.A. Abdin et al. / Journal of Diabetes and Its Complications 24 (2010) 168 –178

Rolka, D. B., Fagot-Campagna, A., & Narayan, K. M. V. (2001). Aspirin use
among adults with diabetes. Estimates from the third national health and
nutrition examination survey. Diabetes Care ,24, 197−201.
Saad, M. F., Knowler, W. C., Pettitt, D. J., Nelson, R. G., Mott, D. M., &
Bennett, P. H. (1989). Sequential changes in serum insulin concentration
during development of non-insulin-dependent diabetes. Lancet ,1,
1356−1359.
Senn, J. J., Klover, P. J., Nowak, I. A., & Mooney, R. A. (2002). Interleukin-
6 induces cellular insulin resistance in hepatocytes. Diabetes ,51,
3391−3399.
Spranger, J., Kroke, A., Mohlig, M., Hoffmann, K., Bergmann, M. M.,
Ristow, M., Boeing, H., & Pfeiffer, A. F. H. (2003). Inflammatorycytokines and the risk to develop type 2 diabetes. Results of the
prospective population-based European Prospective Investigation
into Cancer and Nutrition (EPIC)-Potsdam Study. Diabetes ,52,
812−817.
Tanaka, T., Itoh, H., Doi, K., Fukunaga, K., Shintani, M., Yamashita, J.,
Chun, T. H., Inoue, M., Masatsugu, K., Sawada, N., Saito, T.,Nishimura, H., Yoshimasa, Y., & Nakao, K. (1999). Down regulation ofperoxisome proliferator-activated receptor γexpression by inflamma-
tory cytokines and its reversal by thiazolidinedione. Diabetologia ,42,
702−710.
Temelkova-Kurktschiev, T., Siegert, G., Bergmann, S., Henkel, E., Koehler,
C., Jaross, W., & Hanefield, M. (2002). Subclinical inflammation is
strongly related to insulin resistance but not insulin secretion in a high
risk population for diabetes. Metabolism ,51, 743−749.
Thomas, T., Nadackal, G. T., & Thomas, K. (2003). Aspirin and diabetes:
inhibition of amylin aggregation by nonsteroidal anti-inflammatory
drugs. Experimental and Clinical Endocrinology & Diabetes ,111(1),
8−11.
Unger, R. H. (1995). Lipotoxicity in the pathogenesis of obesity-dependent
NIDDM: genetic and clinical implications. Diabetes ,44, 863−870.Wellen, K. E., & Hotamisligil, G. S. (2003). Obesity-induced inflammatory
changes in adipose tissue. Journal of Clinical Investigation ,112(12),
1785−1788.
Winkler, G., Salamon, F., Salamon, D., Speer, G., Simon, K., & Cseh, K.
(1998). Elevated tumour necrosis factor alpha levels can contribute to the
insulin resistance in type II (non-insulin-dependent) diabetes and
obesity. Diabetologia ,41, 860−862.
Xu, H., Barnes, G. T., Yang, Q., Tan, G., Yang, D., Chou, C. J., Sole, J.,
Nichols, A., Ross, J. S., Tartaglia, L. A., & Chen, H. (2003). Chronicinflammation in fat plays a crucial role in the development of obesity-
related insulin resistance. Journal of Clinical Investigation ,112(12),
1821−1830.
Y
in, M. J., Yamamoro, Y ., & Gaynon, R. B. (1998). The anti-inflammatory agents
aspirin and salicylate inhibi t the activity of IKB kinase. Nature ,396,7 7 −80.
Yki-Jarvinen, H. (1994). Pathogenesis of non-insulin-dependent diabetes
mellitus. Lancet, 343,9 1−95.
Yki-Jarvinen, H. (2004). Thiazolidinediones. Drug Therapeutics ,351(11),
1106−1118.
Yoo, J. Y., & Desiderio, S. (2003). Innate and acquired immunity intersect in
a global view of the acute-phase response. Proc Natl Acad Sci U S A ,
100, 1157 −1162.
Yuan, M., Konstantopoulos, N., Lee, J., Hansen, L., Li, Z. W., Karin, M., &
Shoelson, S. E. (2001). Reversal of obesity- and diet-induced insulinresistance with salicylates or targeted disruption of Ikk(beta). Science ,
293(5535), 1673 −1677.
Zhang, F., Ye, C., Li, G., Ding, W., Zhou, W., Zhu, H., Chen, G., Luo, T.,
Guang M Liu, Y., Zhang, D., Zheng, S., Yang, J., Gu, Y., Xie, X., & Luo,M. (2003). The rat model of type 2 diabetic mellitus and its
glycometabolism characters. Experimental Animmals ,52(5), 401 −407.
Zhang, L., Yu, J., Li, D., Huang, Y., Chen, Z., & Wang, X. (2004). Effects of
cytokines on carbon tetrachloride-induced hepatic fibrogenesis in rats.
World Journal of Gastroenterology ,10(1), 77 −81.178 A.A. Abdin et al. / Journal of Diabetes and Its Complications 24 (2010) 168 –178