SA JOURNAL OF DIABETES & VASCULAR DISEASE
REVIEW
VOLUME 7 NUMBER 2 • JUNE 2010
65
Meeting of the Minds
Common goals, different viewpoints: cardiologists and endocrinologists face off in a
series of stimulating debates
JL Aalbers, P Wagenaar
S
ervier’s Meeting of the Minds, part two, which took place in Cape
Town in March 2010, once again brought together cardiologists
and endocrinologists to share their often opposing views on key issues
relevant to both disciplines.
Should pre-hypertension in type 2 diabetes be treated?
Dr Geoff Bihl, private practice nephrologist, Somerset West
Arguing in favour of treatment, Dr Geoff Bihl, a nephrologist from the
Winelands Kidney and Dialysis Centre in Somerset West, pointed out
that high blood pressure imparts a significant risk for cardiovascular
morbidity and mortality, even in the general population, and that this
risk is two to four times higher in type 2 diabetics. ‘That’s the first argu-
ment for treatment’, he said. ‘Early treatment of hypertension – which
might be considered normal/high-normal or pre-hypertension in non-
diabetics – is therefore essential in diabetic patients. While the opti-
mal blood pressure in diabetics is not clearly defined, anything above
130/80 mmHg should be viewed as requiring treatment.’
Not all diabetics are the same, so it is very important to individualise
treatment. Factors to take into account include:
duration of diabetes
•
macrovascular disease
•
microvascular disease (including that of the kidney)
•
age of the patient
•
presence of autonomic neuropathy.
•
‘It has also been shown that overly quick and aggressive blood pres-
sure reduction can be detrimental in these patients’, continued Dr Bihl.
‘Rather, we should be aiming for a gentle and slow reduction to below
130/80 mmHg over time.’
Pre-hypertension is commonly associated with the metabolic syn-
drome, which is an important factor in the pathogenesis of chronic
kidney disease. Raised blood pressure is a common cause of altered
kidney function, and treating pre-hypertension in diabetics also helps
lower their risk on this front. ‘Treating pre-hypertension has been
shown to reduce the risk of progression to end-stage renal disease by
46%’, said Dr Bihl.
The ADVANCE study showed a reduced relative risk of 17% in com-
bined primary outcomes – major macro- and microvascular events –
with good blood pressure control. ‘We need to look at five- to 10-year
outcomes, and these have shown that good blood pressure control has
profound effects on cardiovascular and renal risk.’
Dr Bihl summarised his key arguments as follows. ‘Diabetics are at
a high risk of cardiovascular and renal morbidity and mortality. The
risk starts early and is worsened by pre-hypertension, which needs to
be defined and diagnosed early. Most diabetics will progress to overt
hypertension. Once lifestyle modifications have been implemented,
the renin–angiotensin–aldosterone system (RAAS) requires early and
aggressive management with drugs such as the ACE inhibitors and
ARBs, which are well researched and inexpensive.’
The case against treatment of pre-hypertension
Dr Aslam Amod, private practice endocrinologist, Durban
Arguing the contrary view, Durban-based endocrinologist Dr Aslam
Amod said that there is no debate about whether increasing blood
pressure confers risk. ‘Ischaemic heart disease and stroke risk rise log-
linearly with increasing systolic and diastolic blood pressure. The term
pre-hypertension was first used in 1939 and resurrected in a 2002
Lancet
study. The question is rather whether pharmacological treat-
ment of pre-hypertension makes a difference.’
In American, but not European guidelines, the term ‘pre-hyperten-
sion’ (120–140 mmHg systolic BP) has superseded the use of ‘normal’
(120–130 mmHg) and ‘high normal’ (130–140 mmHg). Dr Amod’s first
concern therefore is that the definition of pre-hypertension in diabe-
tes is vague, especially when it comes to the diastolic measurement.
‘We treat above 130 mmHg systolic and 80 mmHg diastolic BP, which
means we’re treating normal diastolic and high-normal systolic BP.
Should we be setting the diastolic level at 75 mmHg or even 70 mmHg,
and systolic at 120–129 mmHg?’
Regardless, he argued that pharmacological therapy should not be
used. Few studies have been done in this regard in diabetics, however,
so data have to be extrapolated from studies of pre-hypertension in
non-diabetics.
The TROPHY study, which concluded that treating pre-hypertension
prevented the progression to hypertension, showed that pre-hyperten-
sives receiving candesartan experienced a reduced risk of incident heart
disease and that the treatment was safe and effective. Dr Amod, how-
ever, questioned these findings, pointing out that the patients’ blood
pressures were recorded while on treatment, that their hypertension
was treated rather than prevented and that the study was therefore
compromised. A study of ramipril in pre-hypertension, published in the
Journal of Hypertension
, was similarly compromised by the fact that it
entailed treatment of the endpoint being measured.
He also challenged the findings of the ADVANCE study that blood
pressure reduction in diabetics, even those without hypertension, was
beneficial. He argued that the baseline blood pressure of all involved –
130/80 mmHg – could be construed as hypertensive in this population,
and the lack of any evaluation of patients in the 120–129 mmHg systo-
lic band meant that one could only conclude that those with a history
of hypertension benefited.
By contrast, two lifestyle-modification trials evaluating low-sodium
diets showed a 30% risk reduction in cardiovascular endpoints, sug-
gesting that lifestyle modification had a better outcome than drug
treatment.
Correspondence to: JL Aalbers
Special Assignments Editor, South African Journal of Diabetes and Vascular
Disease
Tel: +27 (0)21 976-4378
Fax: 086 610 3395
e-mail:
P Wagenaar
Gauteng correspondent
S Afr J Diabetes Vasc Dis
2010;
7
: 65–69.
