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58
VOLUME 9 NUMBER 2 • JUNE 2012
RESEARCH ARTICLE
SA JOURNAL OF DIABETES & VASCULAR DISEASE
In the case of physical inactivity, the prevalence (55.7%) was
significantly higher in the diabetics than in the hypertensives and
controls (
p
< 0.001,
p
< 0.001). This agrees with other reports in
the literature.
7,29
Many investigations,
30
including the Framingham
Heart study,
31,7
demonstrated that physical inactivity caused an
increased risk for coronary heart disease.
In Africa, a higher prevalence of diabetes mellitus than of
hypertension was reported among urban, sedentary office workers
than in active, rural farmers.
32
These lifestyle issues apply to
hypertension as well. The explanation for the lower prevalence of
hypertension in that study may derive from the fact that whereas
clinicians actively recommend lifestylemodifications for hypertension
in our environment, normotensive diabetics are counselled on diet
only as a non-pharmacological aspect of their treatment.
In our study, BMI, WC and WHR were the indices of obesity.
The diabetics and hypertensives were significantly more obese
than the normal controls (BMI:
p
< 0.001, WC:
p
< 0.001, WHR:
p
< 0.001). Puepet
et al
.
33
also found that BMI and WHR were
significantly higher in the diabetics than the controls. Using BMI
and WC, the hypertensives in our study were significantly more
obese than the diabetics. However, more diabetics had higher WHR
than the hypertensives.
Obesity is a major risk factor for CVD and this risk is said to
be accentuated when obesity has a predominantly abdominal
component.
34
Obesity as a CVD risk factor in both the diabetics and
hypertensives had insulin resistance as a common denominator.
Using WHR, which is thought to be the most widely used measure
of central adiposity,
35
a prevalence of 72.9% was recorded for
obesity in this study. This is in line with the study by Fadupin
et al
.
36
in Ibadan, but somewhat higher than that in other reports both
locally
37,38
and in Western populations,
7,27
which used BMI as an
index of obesity. However, using BMI, the prevalence of obesity in
our study agreed with that of other reports.
In the Hoorn study, it was observed that WHR and not BMI
was an independent predictor of the incidence of diabetes in
50- to 75-year-old individuals.
39
It also correlated better than BMI
with incidence of hypertension, and there was an inclination to
use measures of central obesity and adiposity rather than BMI in
determining risk.
40
The prevalence of dyslipidaemia (LDL > 2.6 mmol/l, TC > 5.2
mmol/l, TG > 1.7 mmol/l, TC/HDL > 4.1 mmol/l, HDL < 0.9 mmol/l
for males and < 1.1 mmol/l for females) was significantly higher in
the diabetics (82.7%) than in the hypertensives and controls (
p
<
0.001,
p
< 0.001). This was higher than the reported prevalence in
the Western population,
7,24
perhaps because lower lipid values were
used in our study (LDL-C > 2.6 mmol/l).
The observations in this study of significant elevation of total
cholesterol, LDL cholesterol and triglyceride levels is supported by
the work of Isezuo
et al.
,
41
who also reported significantly greater
dyslipidaemia in the diabetic and hypertensive patients than in the
controls. The point of difference however was that HDL cholesterol
levels were similar in all groups studied in their work. In our study
HDL cholesterol levels were lowest in the diabetics, which is typically
expected in diabetic dyslipidaemia:
10,42
high LDL-C, high TC and low
HDL-C levels.
Oxidation of lipoproteins is enhanced in the presence of
hyperglycaemia and hypertriglyceridaemia.
43
The latter is elevated
in diabetes as a result of reduced lipoprotein lipase activity.
44
The
low HDL-C levels reported here are to be expected. Lipoproteins
are glycated more readily in hyperglycaemic states. When HDL is
glycated, its clearance is increased and serum levels become low.
45
The observations in our study agreed with those of Puepet
et al
.,
33
who observed significantly higher (
p
< 0.05) TC, LDL-C
and TG levels in the diabetics than in the controls. However, the
HDL-C levels were similar in all groups, including the hypertensives
who also had higher TC, LDL-C and TG levels than the diabetics,
although not significantly so. The low HDL-C levels observed in the
diabetics in our study were supported by the work of Agboola-Abu
et al
.
37
who, interestingly, recorded an improvement in low HDL-C
levels with treatment.
The TC levels of the diabetics and hypertensives were significantly
higher than those of the controls (
p
< 0.001). The prevalence of
elevated TC levels was the same in the diabetics and hypertensives
(
p
= 1.00). Studies such as Aduba
et al
.
38
from Nigeria and Smellie
et al
.
46
also reported high TC levels in diabetics. The findings of
Adedeji and Onitiri
47
were that TC levels in hypertensives did not
differ significantly from those of normal controls.
Obeka
48
argued that the liberal consumption of alcohol and
intake of a highly thermogenic lipid diet may have been the reasons
for the higher TC levels in the hypertensive subjects in Jos than
reported elsewhere in the country.
49,50
Hypertension and diabetes
are both associated with hyperinsulinaemia, in which there is
disordered lipid metabolism.
The higher TC, LDL-C and TG levels observed in some reports with
a hypertensive diabetic subgroupmay have been related toworsening
hyperinsulinaemic states that these two conditions combined confer
on an individual. It was reported that individuals who will develop
type 2 diabetes mellitus may have higher triglyceride and lower
HDL cholesterol levels than individuals who will not develop type 2
diabetes,
10
which is one fact our study revealed.
Table 5.
Prevalence of CVD risk factors of diabetics and hypertensive
patients.
Index
(CVD risk factors)
Diabetics
n
(%)
Hyperten-
sives
n
(%)
Odds
ratio
χ
2
SAC
6 (8.60)* 4 (5.70)
1.56
6.33
#
Cigarette smoking
5 (7.10)* 0 (0.00)
Undefined 71.55
#
PI
39 (55.7)* 34 (48.6)
1.33
10.10
BMI > 25 kg/m
2
46 (65.7)
52 (74.3)*
1.51
17.61
WC (cm)
30 (42.9)
40 (57.1)*
1.77
40.33
WHR
51 (72.9)
49 (70.0)
1.15
2.06
ECG LVH
4 (5.70)
48 (68.6)* 36.14 844.55
#
Echo LVH
10 (14.3)
52 (74.3)* 17.33 729.28
TC (mmol/l)
39 (55.7)
39 (55.7)
1.00
0.00
HDL- C (mmol/l)
15 (21.4)
13 (18.6)
1.19
4.45
LDL-C (mmol/l)
33 (47.0)* 28 (40.0)
1.33
9.97
TG (mmol/l)
26 (37.1)
25 (35.7)
1.06
0.42
AI
13 (18.6)
16 (22.9)*
0.07
5.62
Dyslipidaemia
58 (82.9)* 52 (74.3)
1.68
21.9
Microalbuminuria
19 (27.2)
19 (27.2)
1.00
0.00
Hyperuricaemia (µmol/l) 6 (8.60)
19 (27.1)*
3.95 116.70
AI, atherogenic index ( TC/HDL); SAC, significant alcohol consumption; BMI,
body mass index; WC, waist circumference; WHR, waist hip ratio; ECG LVH,
electrocardiographically diagnosed LVH; Echo LVH, echocardiographically
diagnosed LVH; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-den-
sity lipoprotein cholesterol; TG, triglycerides; PI, physical inactivity.
#
Yates correction for continuity, *Statistically significant difference.