Type 1 Diabetes; Atherosclerosis İn Childhood
Evidence for an Association between Type 1 Diabetes and Premature Carotid
Atherosclerosis in Childhood
M.E. Atabek;
1 O. Pirgon;1 S. Kurtoglu;2 H. Imamogul3
1
Department of Pediatric Endocrinology and Diabetes; Selc¸ uk University; Faculty of Medicine; Konya; Turkey
2
Department of Pediatric Endocrinology and Diabetes; Erciyes University; Faculty of Medicine; 1 Kayseri; Turkey
3
2 Department of Radiology; Erciyes University; Faculty of Medicine; Kayseri; Turkey
Abstract.
Acute phase proteins have been suggested
to be increased in patients with type 1 diabetes. The
aim of this study was to evaluate the relationship
between serum C-reactive protein (CRP) and intimamedia
thickness (IMT) and functions of the common
carotid artery (CCA) in children and adolescents with
type 1 diabetes.Serum CRP levels were measured in
65 children and adolescents with diabetes (33 girls
and 32 boys; mean age; 12.7 ± 3.8 years; range; 7–l8;
duration of diabetes; 6.9 ± 3.6 years). Age and diabetes
duration; as well as major cardiovascular risk
factors including anthropometric and metabolic
parameters; were matched between girls and boys.
The relations of serum CRP levels to CCA structure
and functions were measured by ultrasonography as
IMT; cross-sectional compliance; cross-sectional distensibility;
diastolic wall stress (DWS); and incremental
elastic modulus (IEM).There was no
significant difference for serum CRP levels between
girls and boys (3.7 ± 1.3 vs 3.2 ± 0.4 mg/L;
p >
0.05). CRP was positively correlated with IMT
(
r = 0.49; p = 0.001); IEM( r = 0.24; p = 0.05);
DWS (
r = 0.58; p < 0.001); and body mass index
(BMI) (
r = 0.28; p = 0.05). In a multivariate
regression model; we included CRP and metabolic
and anthropometric parameters such as duration of
diabetes; HbA1c; BMI; waist:hip ratio; age; and
systolic and diastolic blood pressure as independent
variables in the model for CCA structure and functions.
CRP emerged as an independent correlation
for mean IMT (
b = 0.51; p < 0.001) and DWS
(
b = 0.61; p < 0.001). According to our findings;
CRP was associated with CCA structure and functions
in children and adolescents with type 1 diabetes.
Keywords:
Type 1 diabetes — Common carotid artery
— C-reactive protein — Atherosclerosis
Cardiovascular disease is a common cause of morbidity
and mortality in type 1 diabetes [4]; and carotid
artery stiffness and intima-media thickness (IMT)
measured by ultrasonography are correlated with
atherosclerosis and cardiovascular disease in patients
with type 1 diabetes [3; 15]. According to the literature;
acute phase proteins; known markers of lowgrade
chronic inflammation; are increased in patients
with type 1 diabetes probably independently of glycemic
control and the presence of clinical microvascular
or macrovascular diseases [13].
Inflamation mediates a key role in the pathogenesis
of atherosclerosis [22]. Various cytokines;
growth factors; and inflamatory cells are abundant in
atheromatous plaques. Among inflamation-sensitive
proteins studied to date in relation to cardiovascular
disease risk; higher C-reactive protein (CRP) concentration
is most consistently and strongly related to
risk [19]. Recently; it has been shown that CRP induces
plasminogen activator-1 expression and activity
in human aortic endothelial cells and thus has
implications for both diabetes and atherothrombosis
[8]. A previous study suggested that CRP levels are
elevated and CRP correlates with markers of endothelial
dysfunction in type 1 diabetes [21]. Using
widely available high-sensitivity assays; CRP levels of
<1; 1–3; and >3 mg/Li correspond to low-; moderate-;
and high-risk groups for future cardiovascular
events; respectively. Individuals with low-density
lipoprotein cholesterol (LDL-C) concentrations
<130 mg/dl and CRP levels >3 mg/Li represent a
high-risk group often missed in clinical practice [17].
CRP was a strong predictor of cardiovascular disease
even 8 years after the initial testing [20]. Therefore; in
Correspondence to:
M.E. Atabek; email: meatabek@hotmail.com light of its possible ability to predict cardiovascular
Pediatr Cardiol xx:1–7; 2006
DOI: 10.1007/s00246-006-1199-1
disease in apparently healthy individuals with normal
or high LDL-C; prone to cardiovascular morbidity
and mortality; CRP may be an ideal marker for
screening of apparently healthy child and adolescent
patients with type 1 diabetes.
The aim of this study was to examine whether
CRP is associated with IMT and functions of the
common carotid artery (CCA) (accepted as markers
of early carotid atherosclerosis) in children and
adolescents with type 1 diabetes.
Materials and Methods
Study Population
The baseline study population consisted of 65 patients (33 girls and
32 boys; mean age; 12.7 ± 3.8 years; range; 7–18 years; duration of
diabetes; 6.9 ± 3.6 years) with type 1 diabetes diagnosed according
to the World Health Organization definition. Inclusion criteria
were >1year period from diagnosis of type 1 diabetes; which was
detected
£ 18 years of age and requiring insulin treatment. None of
the individuals studied had diseases known to affect CCA structure
and functions; such as hypertension; hyperlipidemia; and other
cardiovascular diseases; and no one was prescribed any medication
other than antidiabetic drugs. In our center; 24-hour urine samples
were obtained and estimated for albuminuria after excluding proteinuria
due to urinary tract infection. Microalbuminuria (MA)
was defined as 24-hour urinary albumin excretion (UAE) >30mg;
and overt clinical nephropathy was recorded when UAE exceeded
300 mg/24hr in at least two urine samples evaluated within a 12-
week interval. None of the patients had a diagnosis of renal disease
unrelated to diabetes during follow-up. Ophthalmoscopy through
dilated pupils was carried out in all diabetic patients to assess the
presence of retinopathy by the ophthalmologist. Dyslipidemia was
defined as serum cholesterol >200 mg/dl and/or serum triglycerides
(TG) >135 mg/dl (children
‡10 years of age ) and/or
receiving lipid-lowering therapy. Arterial blood pressure was
monitored under standard conditions after at least 5 min at rest in
triplicate at 5-min intervals. Patients were considered as hypertensive
if their arterial blood pressure (BP) exceeding the 95th
percentile using age-; gender-; and height-appropriate BP percentiles
or if they were receiving antihypertensive treatment. Trained
research personnel obtained anthropometric data. Height was
measured using a wall-mounted stadiometer; and weight was
determined using a balance scale. Body mass index (BMI) was
calculated as the ratio of weight (kg) to the square of height (m
2).
Hip circumference and waist circumference were recorded. Tanner
stage was determined by a physician and was based on breast stage
and pubic hair development in girls and on genitalia development
in boys. The institutional review board approved this study; and
written informed consent was obtained from all patients for multiple
comparisons.
Analytical Methods
CRP; BP; body weight; fasting blood glucose; serum glycated
hemoglobin (HbA1c); total cholesterol (TC); HDL cholesterol
(HDL-C); TG; LDL-C; daily insulin dose; and UAE were determined.
Blood samples were collected from the diabetic children
after an overnight fast. Serum glucose; lipid concentrations; and
urine microalbumin were assayed on a Konelab 60i analyzer
(Konelab; Espoo; Finland). Serum HbA1c concentrations were
determined by automated high-performance liquid chromatography
(normal; <6.05
%).
CRP measurements were determined by highly sensitive CRP
(HS-CRP). HS-CRP analysis was carried out using a nephelometry
system (Behring Diagnostics; Deerfield; IL; USA) [16]. In this
method; polystyrene particles coated with monoclonal antibodies
to CRP are agglutinated when mixed with samples containing
CRP. The intensity of the scattered light in the nephelometer depends
on the CRP content of the sample; therefore; the CRP
concentration can be determined vs dilutions of a standard of
known concentration. The method was standardized against the
International Federation of Clinical Chemistry/Community Bureau
of Reference of the Commission of the European Communities/
College of American Pathologists reference preparation [7; 23].
The intra- and interassay coefficients of variation for CRP were 3.3
and 3.2
%; respectively. The reproducibility at the assay detection
limits was 3.1
%. HS-CRP of girls and boys ranged from 1.4 to 6.4
mg/L in children and adolescents with type 1 diabetes. The normal
range of CRP in age- and sex-matched controls was 0.9–2.3 mg/L.
Moreover; we searched; for correlations between CRP and CCA
structure and functions and metabolic and anthropometric
parameters in patients with diabetes.
CCA Ultrasonography
The same sonographer; who was blinded to the participant’s case
status and risk factor levels; did all examinations. High-resolution
B-mode ultrasonography of .the right CCA was performed with an
Acuson Sequoia Acuson; Mountain View; CA; USA) or Toshiba
SSA-370A (Toshiba; Tokyo) ultrasound scanner equipped with a
linear 11-MHz transducer. The participants were examined in the
supine position with the head turned slightly to the left. Longitudinal
images of the CCA were obtained by combined B-mode and
color Doppler ultrasound examinations. The IMT of the CCA far
wall was measured with the electronic calipers of the machines; as
described by Pignoli et al. [13]. The mean IMT was calculated for
each patient as the average of three consecutive measurements of
maximum far wall thickness obtained from the CCA; 20 mm below
the corotid bulb. M-mode ultrasound examinations were recorded
on-line. The maximal end diastolic carotid lumen diameter was
measured at the R wave of the electrocardiogram. Three measurements
of each systolic and diastolic diameter were averaged.
The diameter change was calculated as the difference between the
systolic and diastolic averages [1]. The carotid artery IMT of girls
and boys ranged from 0.4 to 0.6 mm. The normal range of CCA
IMT in age- and sex-matched controls was 0.2–0.4 mm
Lumen cross-sectional area was calculated as
pdD2/4 and wall
cross-sectional area as
p(dD/2 + IMT)2 ) p(dD/2)2. Cross-sectional
compliance (CSC) and distensibility (CSD) of the CCA were
calculated from diameter changes during systole and from simultaneously
measured pulse pressure (
DP) according to the following
formulae: CSC =
p (sD2 ) dD2)/4DP; CSD = (sD2 ) dD2)/(dD2
·
DP) Diastolic wall stress DWS was calculated as mean arterial 3
pressure multiplied by d
D/2 IMT. Whereas compliance provides
information on elasticity of the artery as a hollow structure;
incremental elastic modulus (IEM) provides information on the
properties of the wall material independently from arterial geometry.
This variable was calculated as 3/(1 + lumen cross-sectional
area/wall cross-sectional area) divided by cross-sectional distensibility.
Repeatability of measurements was assessed as previously
described [1; 2].
2 Pediatric Cardiology Vol. xx; No. x; 2006
Data are expressed as mean ± SD; The Kolmogorov–Smirnov
test was applied separately for boys and girls to check the
normality of the variables. Differences between data were studied
using Student’s
t-test. Statistical correlation was assessed using the
Pearson test (
r). Multiple linear regression analysis was performed
in standard and forward stepwise selection to identify independent
factors affecting CCA IMT; CSC; CSD; DWS; and IEM and to
estimate the final predictors of their variability. Statistical significance
was taken as
p < 0.05. Statistical analysis was performed
using the Statistical Package for Social Sciences (SPSS/Windows
version 11.0; SPSS; Chicago; IL; USA).
Results
The characteristics of the study population are shown
in Table 1. The groups were matched for age and
body size. Fourteen females and 11 males were prepubertal.
No significant differences were observed
between the groups with regard to weight; height;
BMI; waist:hip ratio (WHR); pubertal stage (prepubertal
and pubertal); systolic BP; or diastolic BP; TC;
TG; LDL-C; and HDL-C. Moreover; there were no
4
significant differences regarding metabolic and
anthropometric data for both groups. The UAE of all
patients was 15.5 ± 5.1 mg/24hr. None of the patients
withdiabetes had evidence of microvascular
complications; such as diabetic retinopathy; clinical
neuropathy; and overt nephropathy. There was no
significant difference for serum CRP levels between
diabetic girls and boys (3.7 ± 1.3 vs 3.2 ± 0.4 mg/L;
p
> 0.05) (Table 1). The differences for CCA IMT;
CSC; CSD; DWS; and IEM; were not significant
between girls and boys (Table 1).
Patients with diabetes had significantly higher
values than age-and sex-matched controls (
n = 36)
for CRP (3.7 ± 1.4 vs 1.7 ± 0.2 mg/
l; p < 0.001).
Carotid artery IMT levels were significantly lower in
healthy controls (
n = 36) compared to age- and sexmatched
patients with diabetes (0.30 ± 0.08 vs
0.46 ± 0.09 mm;
p = 0.001).
CRP was positively correlated with IMT
(
r = 0.49; p = 0.001); IEM( r = 0.24; p = 0.05);
DWS (
r = 0.58; p <0.001); and BMI (r = 0.28;
p
= 0.05) in children and adolescents with type 1
diabetes (Table 2). CRP showed correlations with
IMT (
r = 0.56; p = 0.005); DWS (r = 0.70; p <
0.001); weight (
r =0.42; p =0.004); BMI (r = 0.47;
p
= 0.02); and diastolic BP (r = 0.36; p = 0.002) in
girls and with IMT (
r = 0.49; p = 0.0l) and DWS
(
r = 0.45; p = 0.03) in boys (Table 2).
In a multivariate regression model for all patients
with diabetes; we included CRP and metabolic and
anthropometric parameters such as duration of diabetes;
HbA1c; BMI; WHR; age; and systolic and
diastolic BP as independent variables in the model for
CCA structure and functions. The independent correlation
for IMT was CRP (
b = 0.51; p<0.001) and
the independent correlation for DWS was CRP
(
b = 0.61; p < 0.001); with the total variance explained
being 25 and 36
%; respectively. CRP emerged
as independent correlations for mean IMT and DWS
in both girls and boys (
b = 0.59; p = 0.005 for IMT
in girls;
b= 0.49; p = 0.02 for IMT in boys; and
b
= 0.72; p < 0.001 for DWS in girls; b= 0.43;
p
= 0.04 for DWS in boys) (Table 3).
Discussion
This study is the first to report that CRP level is
positively correlated with IMT; IEM; and DWS in
children and adolescents with diabetes. According to
our findings; CRP level might be the primary risk
factor for carotid artery stiffness and IMT in children
and adolescents with diabetes; regardless of anthropometric
and metabolic measurements such as
duration of diabetes; HbA1c; BMI; WHR; age; and
systolic and diastolic BP.
Only a few studies have evaluated the association
between CRP concentration and the development of
carotid atherosclerosis in adult subjects [9; 10]. A
Table 1.
Characteristic of 65 childern and adolescents with type 1
diabetes
Girls (
n=33) Boys (n= 32) p
Age (years) 12.4 ± 4.4 13 ± 3.6 NS
Weight (kg) 40.6 ± 14.7 45 ± 15.3 NS
Height (m) 1.45 ± 0.17 1.53 ± 0.18 NS
Body mass index 18.5 ± 2.7 18.6 ± 2.2 NS
Waist:hip ratio 0.78 ± 0.02 0.78 ± 0.04 NS
Systolic BP (mmHg) 112.1 ± 10.2 115 ± 10.5 NS
Diastolic BP (mmHg) 66.4