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56
VOLUME 9 NUMBER 2 • JUNE 2012
RESEARCH ARTICLE
SA JOURNAL OF DIABETES & VASCULAR DISEASE
especially with the metabolic syndrome with hyperinsulinaemia and
insulin resistance in the background, the CVD risk increases.
13
This
usually involves macro- and microvascular complications.
14
Most individuals who will develop cardiovascular disease at some
time in their lifetime are likely to first present to a health worker with
elevated blood pressure. In most of the epidemiological surveys on
CVD, hypertension is usually the commonest risk factor present.
15
Since diabetics die largely from cardiovascular causes, they would
therefore be burdened with many CVD risk factors. This study
was designed to determine the rate of CVD risk factors present in
normotensive diabetics compared with that of hypertensive non-
diabetics, since hypertension is the major risk factor for CVD. The
aim was to present a case for a paradigm shift in the management
of type 2 diabetes patients.
Methods
The study was conducted on 70 normotensive, type 2 DM patients,
70 hypertensive, non-diabetic patients and 71 non-diabetic,
normotensive (normal) patients attending the out-patient diabetes
clinic, cardiology clinic and general out-patient department of the
Jos University Teaching Hospital between November 2005 and May
2006. The WHO consultation on the diagnosis and classification
of DM criteria was used for diagnosis and classification of type
2 diabetes.
16
Systemic hypertension was diagnosed based on the
WHO/ISH writing group statement.
17
A history was taken, with current age, age at diagnosis, gender,
duration of disease and family history of DM or hypertension
and drug history documented. Lifestyle assessment of alcohol
consumption, quantity of cigarettes smoked and physical activity
was also carried out. Significant alcohol consumption (SAC) was
defined as three or more bottles of beer or three calabashes of local
brew per day, cigarette smoking as any smoking in the past month,
and physical inactivity (PI) as restricted to office work, house bound
or unemployed, as prescribed by Levitt
et al
.
18
Height and weight were recorded to the nearest cm and kg,
respectively, as recommended by Dowse and Zimmet,
19
and the
body mass index (BMI) in kg/m
2
was calculated. Waist and hip girths
were measured (with a dressmaker’s tape) to the nearest cm, as
detailed in the NIH guidelines,
20
and the waist-to-hip ratio (WHR)
was determined.
Fasting blood samples (10 ml) were drawn by venepuncture from
each subject into fluoride oxalate tubes and sent to the chemical
pathology laboratory of the hospital within two hours of collection.
Plasma glucosewas estimated by the glucose oxidasemethod, total and
high-density lipoprotein (HDL) cholesterol using the enzymatic endpoint
method, serum uric acid with the phosphotungstic acid method, and
serum creatinine by Jaffe’s method. Low-density lipoprotein (LDL)
cholesterol was calculated using the Friedwald formula.
21
LDL cholesterol (mmol/l) = HDL cholesterol – triglycerides
2.2
A dyslipidaemic subject was one with: TC > 5.2 mmol/l; LDL-C >
2.6 mmol/l; HDL-C < 0.9 mmol/l (male), < 1.1 mmol/l (female);
TG > 1.7 mmol/l; TC/HDL-C > 4.1 mmol/l.
(TC = total cholesterol, LDL-C = low-density lipoprotein cholesterol,
HDL-C = high-density lipoprotein cholesterol and TG = triglycerides.)
Microalbuminuria was only assayed when clinical-grade
proteinuria was absent, using the micral test method. Subjects who
tested positive for nitrite on the urine dipstick test were excluded
from the micral test.
Electrocardiography was carried out on all patients using an AT
two-plus, six-channel ECG machine (Schiller Switzerland) at 25 mm/s
paper speed. A diagnosis of left ventricular hypertrophy (LVH) was
based on Araoye’s criteria.
22
An echocardiographic LVH diagnosis was derived from inter-
ventricular septal thickness or left venticular posterior wall thickness >
12mm in diastole using the Penn cube convention. This was confirmed
by left ventricular mass (LVM), corrected for height.
23
A SONOS 1500
ultrasound system (Hewlett Packard USA) with a 3.5-mHz transducer
was used.
Statistical analysis
The results were analysed using the EPI INFO 2000 (version 1.1.2a)
statistical software. Mean (± SD) was used to describe continuous
variables and proportions for categorical data. The Student’s
t
-test
was used to assess the significance between the means of two
groups. The one-way analysis of variance was used to ascertain
the significance between means of more than two groups. The
Chi-square (
χ
2
) test was used to determine the significance of
the observed differences when comparing groups of subjects.
Probability values < 0.05 were considered significant.
Results
The mean ages (± SD) of the diabetics, hypertensives and controls
were 51.2 (10.63), 49.8 (12.03) and 49.7 (11.02) years, respectively,
F
= 0.37,
p
= 0.69. The diabetics included 34 (48.6%) males and 36
(51.4%) females. The hypertensives consisted of 33 (47.1%) males
and 37 (52.9%) females, while the normal controls were made up of
35 (49.3%) males and 36 (50.7%) females (
p
= 0.97,
χ
2
= 0.07).
The BMI and WC of the hypertensives were significantly greater
than that of the other groups (
p
< 0.01,
p
< 0.01), whereas the
WHR of the diabetics was significantly higher than that of the other
groups (
p
< 0.01). All blood pressure indices were significantly
higher in the hypertensive subjects (
p
< 0.01), whereas the heart
rate (supine and standing) was significantly higher in the diabetics
(
p
< 0.01,
p
< 0.05, respectively). See Table 1 for anthropometric
and clinical characteristics of the study subjects.
Table 1.
Anthropometric measurements and clinical characteristics of the
study population.
Parameters
Diabetics
(
n
= 70)
Hypertensives
(
n
= 70)
Control
(
n
= 71)
BMI (kg/m
2
)
27.15 ± 4.35 29.16 ± 6.07* 24.16 ± 4.34
WC (cm)
93.51 ± 11.64 95.27 ± 14.10* 85.20 ± 10.25
HC (cm)
99.03 ± 9.60 103.9 ± 14.30* 94.92 ± 14.70
WHR
0.94 ± 0.06* 0.92 ± 0.08 0.89 ± 0.05
SBP (st) (mmHg)
123.6 ± 11.07 153.3 ± 19.99* 119.0 ± 12.19
SBP (sup) (mmHg) 129.11 ± 7.81 161.37 ± 20.00* 123.89 ± 9.72
DBP (st) (mmHg)
83.03 ± 5.00 102.97 ± 14.08* 82.38 ± 6.13
DBP (sup) mmHg 80.77 ± 5.28 100.20 ± 13.26* 76.56 ± 10.98
PP (mmHg)
48.3 ± 6.13 61.2 ± 14.34* 47.3 ± 13.28
HR (st) (beats/min)
90.03 ± 12.47* 85.31 ± 13.77
83.49 ± 13.11
HR (sup) (beats/
min)
80.46 ± 10.77* 80.20 ± 13.71 71.52 ± 12.06
BMI, body mass index; WC, waist circumference; HC, hip circumference; WHR,
waist–hip ratio; SBP (st), systolic blood pressure standing; SBP (sup), systolic
blood pressure supine; DBP (st), diastolic blood pressure standing; DBP (sup),
diastolic blood pressure supine; PP, pulse pressure; HR (st), heart rate standing;
HR (sup), heart rate supine. Mean ± SD. *statistically significant difference.