Telomere length, antioxidant status and incidence of ischaemic heart disease in type 2 diabetes

Abstract

Background:
Type 2 diabetes (T2D) is associated with an increased risk of ischaemic heart disease (IHD). An accelerated process of vascular ageing induced by an increased oxidative stress exposure is suggested as potential pathway accounting for this association. However, no studies have explored the relationship between markers of vascular ageing, measures of oxidative stress and risk of IHD in T2D.

Objectives:
To explore the association between plasma antioxidant status, marker of cellular ageing (leukocyte telomere length, LTL) and 10years risk of IHD in patients with T2D.

Methods:
Between 2001 and 2002, 489 Caucasians subjects with T2D were enrolled at the diabetic clinic, University College London Hospital. Plasma total anti-oxidant status (TAOS) and LTL were measured by photometric microassay and RT-PCR, respectively. The incidence of IHD over 10years was determined through linkage with the national clinical audit of acute coronary syndrome in UK.

Results:
At baseline, TAOS was associated with LTL (age adjusted: r=0.106, p=0.024). After 10years, 61 patients developed IHD. Lower TAOS and shorter LTL at baseline predicted an increased IHD risk at follow-up (age adjusted: p=0.033 and p=0.040, respectively). These associations were independent of age, gender, cardiovascular risk factors, circulating levels of CRP and medication differences.

Conclusions:
Reduced TAOS and short LTL are interrelated pathways which predict risk of IHD in patients with T2D. Our findings suggest that antioxidant defences are important to maintain telomere integrity, potentially reducing the progression of vascular ageing in patients with T2D.

Full text

Telomere length, antioxidant status and incidence of ischaemic heart
disease in type 2 diabetes
Stefano Masi
a,b,
⁎, Francesco D’Aiuto
c,1
, Jackie Cooper
d
,KleliaSalpea
e
, Jeffrey W. Stephens
f
, Steven J. Hurel
g
,
John E. Deanfield
a,1
, Steve E. Humphries
d,1
a
National Centre for Cardiovascular Prevention and Outcomes (NCCPO), Institute of Cardiovascular Science, University College London, UK
b
Department of Clinical Gerontology, King's College London, UK
c
Periodontology Department, Eastman Dental Institute, University College London, UK
d
Division of Cardiovascular Genetics, British Heart Foundation Laboratories, Institute of Cardiovascular Science, University College London, UK
e
Institute of Molecular Biology and Genetics, Biomedical Sciences Research Center “Alexander Fleming”, Athens, Greece
f
Diabetes Research Group, College of Medicine, Swansea University, Swansea, UK
g
Department of Endocrinology, University College London Hospital, London, UK
abstractarticle info
Article history:
Received 6 J anuary 2016
Received in revised form 1 April 2016
Accepted 16 April 2016
Available online 22 April 2016
Background: Type 2 diabetes (T2D) is associated with an increased risk of ischaemic heart disease (IHD). An ac-
celerated process of vascular ageing induced by an increased oxidative stress exposure is suggested as potential
pathway accounting forthis association. However, no studies have explored the relationship between markersof
vascular ageing, measures of oxidative stress and risk of IHD in T2D.
Objectives: To explore the association between plasma antioxidant status, marker of cellular ageing (leukocyte
telomere length, LTL) and 10 years risk of IHD in patients with T2D.
Methods: Between 2001 and 2002, 489 Caucasianssubjects with T2D were enrolled at the diabetic clinic, Univer-
sity College London Hospital. Plasma total anti-oxidant status (TAOS) and LTL were measured by photometric
microassay and RT-PCR, respectively. The incidence of IHD over 10 years was determined through linkage with
the national clinical audit of acute coronary syndrome in UK.
Results: At baseline, TAOS was associated with LTL (age adjusted: r = 0.106, p = 0.024). After 10 years, 61 pa-
tients developed IHD. Lower TAOS and shorter LTL at baseline predicted an increased IHD risk at follow-up
(age adjusted: p = 0.033 and p =0.040, respectively). These associations were independent of age, gender,car-
diovascular risk factors, circulating levels of CRP and medication differences.
Conclusions: Reduced TAOS and short LTL are interrelated pathways which predict risk of IHD in patients with
T2D. Our findings suggest thatantioxidant defencesare important to maintain telomere integrity, potentially re-
ducing the progression of vascular ageing in patients with T2D.
© 2016 The Authors. Published by Elsevier Ireland Ltd. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/).
Keywords:
Diabetes
Cardiovascular risk
Oxidative stress
Telomeres
1. Introduction
Type 2 diabetes mellitus (T2D) is a chronic disease characterized by
multiple metabolic derangements, which disrupt the balance between
reactive oxygen species and antioxidant defences at the cellular level
[1]. Antioxidant capacity of plasma is the primary measure and marker
to evaluate the statusand potential of oxidative stressin the body. Plas-
ma contains many compounds, which function against the oxidative
stressors in the body thus protecting the cell and cellular biomolecules
from being damaged. The reduced antioxidant capacity described in
patients with diabetes results in greater exposure to oxidative stress
and subsequent damage to proteins, lipids, and DNA, which leads to a
rapid deterioration of a broad range of cellular functions and premature
cellular ageing [2,3]. These mechanisms underpin the development of
several diabetic complications, including ischaemic heart disease
(IHD) [4]. T2D can therefore be regarded as a model of accelerated
biological ageing due to increased levels of oxidative stress exposure,
and the increased risk of IHD as a manifestation of premature vascular
ageing [5].
Over the last ten years, epidemiological studies have suggested that
peripheral blood leukocyte telomere length (LTL) can be a useful bio-
marker of cardiovascular ageing. Multiple reports [6–9], including a re-
cent meta-analysisand GWAS study [10,11], suggested that LTL is onthe
causal pathways for IHD. The association between LTL and IHD is
thought to be mediated by oxidative stress exposure which is currently
International Journal of Cardiology 216 (2016) 159–164
⁎Corresponding author at: Inst itute of Cardiovascular Science, University College
London, Level 2, Nomura House, 1 St Martin's Le Grand, EC1A 4NP London, UK.
E-mail address: s.masi@ucl.ac.uk (S. Masi).
1
These authors equally contributed to this work.
http://dx.doi.org/10.1016/j.ijcard.2016.04.130
0167-5273/© 2016 The Authors. Published by Elsevier Ireland Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Contents lists available at ScienceDirect
International Journal of Cardiology
journal homepage: www.elsevier.com/locate/ijcard

considered to be an important driver of atherosclerosis and its compli-
cations [12] as well as to cause a faster LTL attrition [13].However,the
impact of a reduced antioxidant capacity on LTL and risk of IHD has
not been explored in patients with T2D.
We have studied a well characterised cohort of patients with T2D in
order to explore the relationship between a baseline measure of total
serum antioxidant capacity and LTL with subsequent risk of IHD over
10 years.
2. Methods
2.1. Study sample
The University College Diabetes and Cardiovascular disease (UDAC)
study comprises 1011 individuals, who were recruited consecutively
from the diabetes clinic at UCL Hospitals in 2001–2. The study was de-
signed to investigate the association between inflammatory/metabolic
genes and biochemical risk factors implicated in IHD in patients with di-
abetes. The study has been described in detail elsewhere[14,15]. All pa-
tients had type 1 or type 2 diabetes according to WHO criteria [16].
Anthropometric measures (height, weight and BMI), blood pressure
and blood samples as well as information on smoking history and cur-
rent medication use were collected during their routine diabetes clinic
appointment. Our analysis focuses on the subgroup of individuals of in-
dividuals with a diagnosis of T2D, of Caucasian origin and with available
measures of plasma total anti-oxidant status (TAOS), LTL and cardiovas-
cular outcome (n = 489, Fig. 1S of Supplementary Material). The ratio-
nale for the restriction of the analysis to the T2D and Caucasian groups
was to reduce the heterogeneity of our study sample, due to the
known differences in the pathogenesis of cardiovascular complication
between different types of diabetes [17] and the different LTL distribu-
tions and rates of attrition amongst ethnic groups [18,19]. Further, de-
spite multiple studies documented that LTL can predict the risk of IHD
in White American and Caucasian populations, there are no reports as
of yet on South Asian populations with or without diabetes. Ethical ap-
proval was granted by UCL/UCLH Ethics Committee and all subjects
gave written informed consent.
2.2. Plasma total anti-oxidant status and cardiovascular risk factor assays
Plasma samples were collected within the 12-month recruitment
period andstored immediately at −80 °C. Plasma total anti-oxidant sta-
tus (TAOS) was measured by Sampson's modification of Laight's photo-
metric microassay [20], using 2.5 μL citrated plasma samples in 96-well
ELISA plates. TAOS was selected as: a) it correlates with markers of ox-
idative damage in peripheral blood of patient with diabetes [20,21];
b) there is already evidence supporting a different anti-oxidant status
of patients with type 1 or type 2 diabetes when compared to healthy
controls [22,23]; c) it is associated with subclinical atherosclerosis coro-
nary artery disease events in observational and longitudinal studies in-
cluding patients with and without diabetes [21,24]. Inter- and intra-
assay coefficients of variation were 14.1% and 4.3%, respectively. Levels
of total cholesterol, triglycerides, HDL cholesterol and HbA1c were
assayed according to standard chemistry protocols [25]. LDL cholesterol
was calculated by the Friedwald equation.
2.3. DNA extraction and LTL assay
Leukocyte DNA was extracted by the salting-out method [26].Telo-
mere length was measured using a validated quantitative PCR-based
method as previously described [27].Briefly, the relative telomere
length was calculated as the ratio of telomere repeats to single-copy
gene (SCG) copies (T/S ratio). For each sample the quantity of telomere
repeats and the quantity of SCG copies were determined in comparison
to a reference sample in a telomere and a SCG quantitative PCR, respec-
tively. The raw data from each PCR was analysed using the comparative
quantification analysis (Rotor-Gene 6000 software, Corbett Research
Ltd., Cambridge, UK). All PCRs were performed on the Rotor-Gene
6000 (Corbett Research Ltd., Cambridge, UK). The coefficient of varia-
tion in repeated measurements was 5.6%.
2.4. Coronary heart disease data
Data on incident IHD disease was retrieved from the Myocardial Is-
chaemia National Audit Project(MINAP), held within the National Insti-
tute of Cardiovascular Outcome and Research (NICOR). This is a national
registry of patients admitted to hospitals in England and Wales with
acute coronary syndromes (ACS). It was established in 1998 to provide
participating hospitals with a common mechanism for auditing perfor-
mance against standards defined in the National Service Framework
for Coronary Heart Disease [28]. Data collection began in October 2000
and by mid-2002 all acute hospitals in England and Wales were partic-
ipating in the registry. The characteristics, organization, availability,
data quality, validation and accessibility of cardiovascular outcome
data contained in the MINAP have been previously described [29].A
new diagnosis of IHD disease was identified using hospital discharge re-
cords, markers of myocardial necrosis, results of coronary angiograms
and coded electrocardiographic findings, in accordance with the inter-
nationally agreed definition of ST-segment elevation myocardial infarc-
tion (STEMI) [30] and acute coronary syndrome without persistent ST-
segment elevation [30–32].
2.5. Statistical analysis
Mean values between groups were compared using two sample t-
tests. Normality was tested using the Shapiro–Wilk test. Variables were
log-transformed where necessary to normalise the distribution and geo-
metric means and approximated standard deviations are reported for
these variables with t-tests performed on the log-transformed data.
Where the data could not be normalised, medians and interquartile
ranges are presented and differences were tested using the Mann–Whit-
ney U test. For categorical variables, chi-squared tests were used. Associ-
ation between continuous variables was assessed by Spearman rank
correlation. Adjustment was made for covariates by including them as
terms in regression or logistic regression models. Particularly, a series of
multivariable regression models were fitted to examine whether tradi-
tional CV risk factors and other potential confounders influenced the as-
sociation observed between LTL and the risk of IHD disease. Results
from three multiple regression models are reported: model 1 = age
adjusted; model 2 = model 1 + adjustments for sex, HbA1c and
smoking; model 3 = model 2 + adjustments for total cholesterol,
blood pressure, C-reactive protein (CRP) and medications. Additionally,
we explored whether further adjustment of model 2 for specific classes
of anti-hypertensive medications (angiotensin converting enzyme, an-
giotensin receptor blockers or calcium channel blockers) had an impact
ontheassociationofTAOSorLTLwithIHD.Theαvalue for statistical sig-
nificance for associations was set at 0.05. Analyses were performed with
STATA version 13.
3. Results
3.1. Baseline characteristics
At baseline, the patients studied were overweight, exhibited subop-
timal gluco-metabolic control, and relatively high levels of blood pres-
sure (Table 1). The average TAOS was 44.8% [36.5–53.3] and it was
higher in people with longer LTL (unadjusted: r = 0.093, p = 0.046;
age adjusted: r = 0.106, p = 0.024) and higher levels of HDL-
cholesterol, while it was reduced in patients with elevated glucose,
HbA1c and triglycerides levels(Table 1). Furthermore, LTL was inversely
associated with age (r = −0.150; p = 0.002), while there were no dif-
ferences based on gender or cigarette smoking distribution, nor was LTL
160 S. Masi et al. / International Journal of Cardiology 216 (2016) 159–164

associated with traditional cardiovascular risk factors including BMI,
total cholesterol, HDL-cholesterol, systolic and diastolic blood pressure
and HbA1c. Subjects with shorter LTL tended to have elevated levels of
circulating CRP (Table 1).
3.2. Cardiovascular outcomes
After 10 years, 61 patients (12.5%) developed IHD disease. Patients
with IHD had higher baseline BMI and CRP but lower levels of HDL-
cholesterol compared to those in the non-ischaemic group (Table 2).
Notably, the IHD disease group had lower baseline TAOS compared to
the non-ischaemic group (unadjusted: p = 0.033; adjusted for age:
p = 0.016) (Fig. 1). This association was not affected by adjustments in-
cluded in model 2 (p = 0.028) and remained significant in the fully ad-
justed model (p = 0.022) (Table 3). Similarly, age-adjusted LTL was
shorter in the IHD disease group compared to the non-ischaemic
group (unadjusted: p = 0.040; adjusted for age: p = 0.039) (Fig. 2).
This difference was not affected by adjustments included in model 2
(p = 0.034) and remained significant in the fully adjusted model
(model 3, p = 0.020) (Table 4). Adjustment for medication use
(Model 3 of Table 3 and 4) as well as for different classes of anti-
hypertensives did not materially affect the association between TAOS
and IHD, nor the association between LTL and IHD (Tables 1S and 2S
of Supplementary Material).
4. Discussion
This is the first study to explore the association between LTL, antiox-
idant capacity and subsequent risk of IHD disease in patients with T2D.
We showed that baseline LTL was inversely related to TAOS and that
shorter LTL and lower TAOS at baseline predicted IHD disease risk
over 10 years, independently from traditional cardiovascular risk fac-
tors. This suggests that a reduced antioxidant capacity increases the
risk of IHD in patients with T2D, potentially accelerating the vascular
ageing process by damaging telomere sequences.
Previous reports have described associations between LTL and inci-
dence of IHD in healthy populations [6–8]. In T2D, only observational
studies have reported associations between LTL and prevalence of dia-
betes complications [33]. We now show that LTL can predict future inci-
dence of IHD disease in prospective follow-up over 10 years. This is
likely to be due to the unique ability of LTL to reflect an individual's cu-
mulative exposure to inflammation and oxidative stress. Indeed, it is
now well established that oxidative stress exposure increases LTL short-
ening and contributes to the initiation and progression of atherosclero-
sis. A higher oxidative stress exposure results in LDL oxidation, vascular
inflammation and increased vulnerability of atherosclerotic plaques to
rupture [12]. Similarly, oxidative stress exerts a major influence on telo-
mere dynamics for two principal mechanisms. Firstly, the GGG triplets
on the telomere sequence are highly sensitive to the hydroxyl radical
[13]. Thus, conditions characterised by increased levels of oxidative
Table 1
Baseline characteristics of the study sample and their associations with TAOS and LTL.
Characteristics N = 489 Association with
TAOS
Association with
LTL
rprp
Age, years
e
67 [24–91] 0.078 0.089 −0.150 0.002
Smoking, %
c
77 (16%) −0.0007 0.987 −0.019 0.685
BMI, Kg/m2
b
29.4 ± 5.6 −0.058 0.204 −0.0025 0.957
SBP
f
,mmHg
b
141 ± 19 0.075 0.104 0.061 0.192
DBP
f
,mmHg
b
79 ± 11 0.067 0.145 −0.034 0.473
Total cholesterol,
mmol/L
a
5.15 ± 1.06 −0.035 0.450 0.040 0.396
LDL, mmol/L
a
2.79 ± 0.92 0.023 0.625 0.068 0.149
HDL, mmol/L
b
1.29 ± 0.37 0.132 0.004 −0.003 0.942
Triglyceride, mmol/L
b
1.93 ± 1.09 −0.178 0.0001 −0.055 0.239
CRP, mg/L
b
1.76 ± 1.51 0.074 0.106 −0.092 0.051
Glucose, mmol/L
b
10.00 ± 4.31 −0.164 0.0003 −0.054 0.251
Hba1c, % (mmol/mol)
b
7.66 ± 1.64 −0.100 0.030 0.011 0.817
TAOS, %
d
44.8 [36.5–53.3] ––0.106 0.024
Age adjusted LTL, T/S
ratio
b
0.97 ± 0.21 0.106 0.024 ––
Statin treatment, %
c
124 (26%) −0.010 0.833 0.022 0.646
BP lowering, %
c
316 (65%) −0.0007 0.987 −0.013 0.785
Apart from theassociation with age, all other associations with LTL were adjusted for age.
The αvalue for statistical significance for associations was set at 0.05.
a
Mean ± standard deviation for normally distributed variables.
b
Geometric mean ± approximate standard deviation for log-normally distributed
variables.
c
N (percentage) for binary variables.
d
Median [interquartile range] for not normally distributed variables.
e
Age is show as median [range].
f
SBP: systolic blood pressure; DBP: diastolic blood pressure.
Table 2
Baseline differences between ischaemic and non-ischaemic groups.
Characteristics Non-ischaemic
N = 428
Ischaemic
N=61
p value
Age, years
e
66 [24–91] 67 [44–84] 0.725
Smoking, %
c
70 (17%) 7 (12%) 0.344
BMI, Kg/m2
b
29·1 ± 5.6 30.9 ± 5.8 0.026
SBP
f
,mmHg
b
142 ± 18 140 ± 23 0.444
DBP
f
,mmHg
b
79 ± 11 76 ± 10 0.037
Total cholesterol, mmol/L
a
5.18 ± 1.08 4.94 ± 0.97 0.094
LDL, mmol/L
a
2.80 ± 0.93 2.69 ± 0.90 0.353
HDL, mmol/L
b
1.30 ± 0.38 1.17 ± 0.29 0.004
Triglyceride, mmol/L
b
1.90 ± 1.08 2.17 ± 1.08 0.087
CRP, mg/L
b
1.70 ± 1.46 2.17 ± 1.90 0.041
Glucose, mmol/L
b
9.94 ± 4.33 10.38 ± 4.15 0.471
Hba1c, % (mmol/mol)
b
7.67 (60) ± 1.67 7.63 (60) ± 1.43 0.865
TAOS, %
d
44.5 [36.9–53.3] 40.5 [32.3–47.8] 0.033
Age adjusted LTL, T/S ratio
b
0.98 ± 0.21 0.92 ± 0.18 0.040
Statin treatment, %
c
94 (22%) 30 (50%) b0.001
BP lowering, %
c
268 (63%) 48 (79%) 0.019
Differences between ischaemic and non-ischaemic groups were assessed using unpaired
t-test fornormally or log-normally distributedvariables. Wherethe data could not be nor-
malised,medians and interquartile rangesare presentedand differences weretested using
the Mann–Whitney U test. χ[2] tests were used for categorical variables.
a
Mean ± standard deviation for normally distributed variables.
b
Geometric mean ± approximate standard deviation for log-normally distributed
variables.
c
N (percentage) for binary variables.
d
Median [interquartile range] for not normally distributed variables.
e
Age is show as median [range].
f
SBP: systolic blood pressure; DBP: diastolic blood pressure.
Fig. 1. Box plot showing difference of TAOS at bas eline between isc haemic and non-
ischaemic groups (median and IQR); p = 0.033.
161S. Masi et al. / International Journal of Cardiology 216 (2016) 159–164

stress exposure, such as T2D, can result in a longer stretch of telomeres
being lost with each cell replication [13]. This has previously been con-
firmed by Sampson et al., who documented an association between ox-
idative DNA damage and monocyte telomere length in patients with
T2D [34]. Secondly, in contrast to genomic DNA,telomeric DNA was re-
ported to be deficient in the repair of single-strand breaks [35].Asare-
sult, telomeres appearto be especially vulnerable to the accumulation of
ROS-induced DNA-strand breaks [36].
We found an increased risk of IHD disease in T2D patients with re-
duced antioxidant capacity. A decreased antioxidant capacity is associ-
ated with an increase in oxidative stress which is thought to be on the
causal pathway for diabetic vascular complications. Our study supports
this hypothesis by demonstrating an inverse relationship of TAOS with
risk of IHD disease risk. In line with our findings, Broedbaek et al. recent-
ly showed that higher urinary markers of nucleic acid oxidation are as-
sociated with increased mortality in newly diagnosed patients with T2D
[37]. Despite this, the majority of clinical trials of antioxidants have
failed to show significant improvement in CV outcomes in patients
with diabetes [38,39]. This may be due to the inability of exogenously
provided compounds (like antioxidant vitamins) to reach intracellular
compartments and prevent oxidative damage to key proteins, lipids
and nucleic acids [40].
The association between TAOS and LTL with incident IHD disease
was independent of traditional cardiovascular risk factors. For example,
while people with lower TAOS had higher HbA1c and triglycerides with
lower HDL-cholesterol, adjustment for these cardiovascular risk factors
did not attenuate the association between TAOS and IHD. Similarly,
higher CRP tended to be associated with shorter LTL, as expected [41–
43], but addition of CRP to our fully adjusted model did not affect our re-
sults. This finding could be partially due to comparable cardiovascular
risk factors burden between groups included in this study. Indeed LDL
cholesterol levels were similar between the ischaemic and control
groups, although use of statin was more prevalent in the former. This
observation suggests that, whilst optimal treatment could normalize
cardiovascular risk factors of people with T2D, this might not restore
the antioxidant defences and counteract their impact on the cellular
aging process. This hypothetical mechanism could explain the increased
residual risk of cardiovascular events observed in people with T2D de-
spite the improved cardiovascular risk factor burden.
Our study has limitations, which may lead to an underestimation of
the strength of the associations between LTL and TAOS with incident
IHD disease. Firstly, the primary outcome was IHD due to the limited in-
formation available on other atherosclerotic complications of diabetes. It
is now well established that people with diabetes experience “silent”IHD
during their lifetime. Secondly, the lack of data on non-cardiac causes of
mortality precluded the opportunity to use an event-free survival ap-
proach in our statistical analysis. This, together with the similar follow-
up length for all participants (range 9.3 to 10.5 years), led us to use logis-
tic regression as preferred analytical models to explore the associations
between TAOS and LTL with IHD. Thirdly, we could not perform measures
of intracellular antioxidants. TAOS provides an estimation of total antiox-
idant capacity, which in turn is dependent on the contributions of albu-
min, bilirubin and urate. We cannot exclude therefore that measures of
intracellular oxidative stress or the assessment of additional extracellular
antioxidants could provide better estimation of the influence of antioxi-
dant capacities on LTL and risk of future cardiovascular events. These fac-
tors do not attenuate, however, the importance of the biological
associations emerging from our data. Larger epidemiological studies
with multiple measures of LTL and oxidative stress will be necessary to
provide a more accurate estimation of the associations between TAOS,
LTL and IHD.
Table 3
Multivariable models assessing differences of TAOS between non-ischaemic and ischae-
mic heart disease groups.
Models Variables Logistic regression
OR
a
(95% CI) p values
Model 1 Age (1 year increase) 1.01 (0.98–1.03) 0.537
TAOS (1 quintile increase) 0.78 (0.64–0.95) 0.016
Model 2 Age (1 year increase) 1.01 (0.98–1.03) 0.555
Sex (female: male) 0.61 (0.34–1.11) 0.104
Hba1c (1 SD increase) 1.04 (0.78–1.38) 0.788
smoking (current vs. non) 0.67 (0.29–1.57) 0.361
TAOS (1 quintile increase) 0.80 (0.65–0.98) 0.028
Model 3 Age (1 year increase) 1.00 (0.97–1.03) 0.880
Sex (female: male) 0.45 (0.23–0.86) 0.017
Hba1c (1 SD increase) 0.98 (0.71–1.34) 0.984
Smoking (current vs. non) 0.73 (0.30–1.78) 0.494
SBP (1 SD increase) 1.13 (0.76–1.68) 0.552
DBP (1 SD increase) 0.64 (0.43–0.96) 0.030
Blood pressure medications 1.58 (0.79–3.19) 0.197
Lipid lowering medications 3.29 (1.77–6.11) 0.0002
CRP (1 SD increase) 1.48 (1.09–2.03) 0.013
TAOS (1 quintile increase) 0.78 (0.63–0.96) 0.022
a
Odds ratio for a unit increase of the independent variable.
Fig. 2. Box plot showing difference of LTL at baseline between ischaemic and non -
ischaemic groups; analysis adjusted for age; p = 0.040.
Table 4
Multivariable models assessing differences of LTL between non-ischaemic and ischaemic
heart disease groups.
Models Variables Logistic regression
OR
a
(95% CI) p values
Model 1 Age (1 year increase) 1.00 (0.98–1.03) 0.816
T/S ratio (1 SD increase) 0.74 (0.55–0.99) 0.039
Model 2 Age (1 year increase) 1.00 (0.98–1.03) 0.819
Sex (female: male) 0.56 (0.31–1.04) 0.067
Hba1c (1 SD increase) 1.02 (0.77–1.35) 0.880
Smoking (current vs. non) 0.59 (0.24–1.45) 0.248
T/S ratio (1 SD increase) 0.72 (0.53–0.97) 0.034
Model 3 Age (1 year increase) 0.99 (0.96–1.03) 0.705
Sex (female: male) 0.42 (0.21–0.83) 0.013
Hba1c (1 SD increase) 1.00 (0.72–1.39) 0.984
smoking (current vs. non) 0.72 (0.28–1.85) 0.497
SBP (1 SD increase) 1.09 (0.72–1.64) 0.681
DBP (1 SD increase) 0.67 (0.43–1.02) 0.062
Blood pressure medications 1.73 (0.82–3.62) 0.148
Lipid lowering medications 3.83 (2.02–7.25) 0.00004
CRP (1 SD increase) 1.29 (0.94–1.78) 0.121
T/S ratio (1 SD increase) 0.69 (0.50–0.94) 0.020
a
Odds ratio for a unit increase of the independent variable.
162 S. Masi et al. / International Journal of Cardiology 216 (2016) 159–164

5. Conclusions
A single measure of antioxidant capacity and LTL predicted 10 years
IHD risk in patients with diabetes. This association is likely to depend
upon an increased damage of the telomere sequence in people with di-
abetes and suggests that a process of early vascular ageing induced by
oxidative stress contributes to increase cardiovascular morbidity and
mortality in diabetes.
Author contribution
Design of original surveyand participant recruitment: SEH, JWS, SJH;
study design: SM, SEH, JED, FDA; telomere assay design and set up: SEH,
KS; telomere assays: SM; biochemical assays: KS, JWS; statistical analy-
sis: JK; data interpretation: SM, SEH, JED, FDA; manuscript preparation:
SM, FDA; manuscript critical revision: SEH, JED, JK, KS, JWS, SJH.
Conflict of interest
The authors report no relationships that could be construed as a con-
flict of interest.
Acknowledgments
This research was funded by the BHF (PG/08/008) and supported by
the National Institute for Health Research (NIHR), University College
London Hospitals (UCH), Biomedical Research Centre (BRC). The au-
thors acknowledge the MINAP group at the NICOR (National Institute
for Cardiovascular Outcomes Research) for accessing the vascular inci-
dent data. SEH is the British Heart Foundation Professor of Cardiovascu-
lar Genetics and UCL. SM was supported by the Rosetrees Trust, was
awarded of a NIHR Career Development Fellowship and of the
European Grant in Hypertension from the European Society of Hyper-
tension and Servier and holds a Clinical Lectureship in Geriatric Medi-
cine supported by NIHR. FD holds a Clinical Senior Lectureship Award
supported by the UK Clinical Research Collaboration. The UDAC Study
was established by JWS within a D iabetes UK clinical training fellowship
(BDA: RD01/0001357).
Appendix A. Supplementary data
Supplementary data to this article can be found online at http://dx.
doi.org/10.1016/j.ijcard.2016.04.130.
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