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VOLUME 9 NUMBER 2 • JUNE 2012
59
SA JOURNAL OF DIABETES & VASCULAR DISEASE
RESEARCH ARTICLE
Hyperuricaemia was significantly more prevalent in the
hypertensives than in the diabetics and the controls (
p
< 0.001,
p
< 0.001). Interestingly, the prevalence of hyperuricaemia was
significantly higher in the control group than in the diabetics (
p
<
0.001). The higher prevalence of hyperuricaemia observed in the
hypertensives (27.1%) may have been due to drugs such as thiazide
diuretics, which are taken for the control of blood pressure, and
these drugs increase serum uric acid as a metabolic consequence.
The prevalence of hyperuricaemia was 8.6% in the diabetics and
19.7% in the controls. It is believed that once diabetes develops,
serum uric acid levels fall. This action is a function of glycosuria
stimulating renal urate excretion. Therefore, serum concentrations
of uric acid are elevated in insulin resistance but not necessarily in
diabetes.
51
Interestingly, in studies of type 2 diabetes, persistent hyper-
uricaemia correlated with poor metabolic control, hyperfiltration
and decreased risk of progression of renal disease.
52
Hyperuricaemia
is therefore thought to be more important in the development
of insulin resistance than in the maintenance of the pre-diabetic
state.
The prevalence of microalbuminuria was 27.2% in our study,
having removed subjects with overt proteinuria. This observation
is in line with that reported by Alebiosu
et al.
,
53
who reported a
prevalence of 25.3%, but contrasts with findings of other Nigerian
investigators. Adedapo
et al
. in Ibadan
54
reported a prevalence
of 60% among diabetic patients and 30% among the controls.
The contribution of background renal insult was highlighted as
the probable reason for the high prevalence of microalbuminuria.
Tranche
et al.
,
27
working in a Western population, reported a
prevalence of 34.7%.
Microalbuminuria has been related to insulin resistance and
can occur prior to the onset of diabetes.
55
The higher prevalence
of microalbuminuria in these other reports may possibly be due
to differences in age, duration of disease, the influence of blood
pressure, which was removed in our study, and the prevalence of
obesity in the study population. The prevalence of 27.2% recorded
in our study was significantly higher than in the controls (
p
< 0.001)
and the same as that observed for the hypertensives (
p
= 1.00)
The prevalence of echo-diagnosed LVH was significantly higher
in the diabetics (14.3%) than in the controls (
p
< 0.001). This was
higher than the prevalence of 4.76% reported by Tranche
et al
.
27
in
their cohort. The higher prevalence recorded in our study may be
related to the known fact that blacks have an increased tendency
to develop LVH.
56
However it is unclear whether this is due to
genetic or environmental factors. The observation of LVH in the
normotensive diabetics and even in the controls was not surprising
since it is known that LVH may precede hypertension.
57.
It is not surprising that a prevalence of echo-diagnosed LVH of
74.3% was observed in the hypertensive group in our study, since
LVH occurs as an early response to hypertension.
58
LVH has been
demonstrated among diabetic African patients and up to 50% of
asymptomatic patients may present with these abnormalities.
59,60.
This was in contrast to the prevalence of 14.3% recorded in the
normotensive diabetics in our study. There is a paucity of data on
echo-diagnosed LVH among normotensive diabetics. However,
Osuntokun
et al
.
61
found that 11% of 556 diabetic Nigerian patients
had an abnormal ECG, mainly LVH and strain pattern, associated
with hypertension.
Electrocardiographic (ECG) diagnosis of LVH depends on the
criteria used and there is a paucity of data on ECG-diagnosed LVH
in normotensive diabetics in both African and Western populations.
Araoye
et al
.
62
reported a prevalence of 70.5% using Sokolow-Lyon
criteria in a study of 288 hypertensive Nigerians. ECG-diagnosed
LVH was observed in 68.6% of the hypertensives and 5.7% of the
diabetics. Huston
et al.
63
reported ECG-diagnosed LVH of 3–29%,
based on different criteria, in a population of civil servants in Benin,
Nigeria. The prevalence of ECG-diagnosed LVH was significantly
higher (11–49%) among those with hypertension, which was 19%
of the population.
There was no significant difference in mean serum creatinine levels
between all three groups (Table 2). However, in the study of Puepet
et al
.,
33
the mean serum creatinine level of the diabetics studied
was significantly higher than that of the controls (
p
= 0.03). An
interesting observation in this study was that mean serum creatinine
level of the normal group was higher than that of the diabetics and
hypertensives but not significantly so (
p
= 0.55). The reason for this
could not readily be found but may have been a reflection of renal
dysfunction in the population. In one study, individuals with normal
blood pressure were found to have chronic kidney disease, albeit
lower than those with atherosclerotic disease states.
64
It has been shown that there is a strong correlation between
serum creatinine levels and cardiovascular event rates. The hazards
ratio for a patient with a serum creatinine level of 1.4 to 2.0 mg/dl
was 40% higher than that of the normal controls, for the patient
with microalbuminuria, 59% higher, and for the patient with both
increased serum creatinine levels and microalbuminuria, 108%
higher.
65
The high cardiovascular risk conferred by minor renal
dysfunction could perhaps be explained by the known endothelial
cell dysfunction in incipient renal disease. However, creatinine is
a notoriously insensitive reflection of glomerular filtration as it is
strikingly influenced by muscle mass and other confounding factors.
Conclusion
This study found that apart from markers of left ventricular
hypertrophy and hyperuricaemia, the diabetic patients equaled
the hypertensive subjects with regard to cardiovascular disease
morbidity. Interestingly, they were worse off with regard to
significant alcohol use, cigarette smoking and physical inactivity. This
calls for a paradigm shift in the management of diabetic patients.
Lifestyle modification must be stressed for diabetics as much as for
hypertensive patients. The diabetic patients’ prescribed diet would
need to be adjusted since their lipid profiles were worse than the
hypertensives, and regular cardiovascular evaluation should form
part of their monitoring.
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