104
VOLUME 9 NUMBER 3 • SEPTEMBER 2012
REVIEW
SA JOURNAL OF DIABETES & VASCULAR DISEASE
Correspondence to: Brian Rayner
Division of Nephrology and Hypertension,
University of Cape Town, Cape Town
Tel: +27 (0)21 404-3495
e-mail:
S Afr J Diabetes Vascular Dis
2012;
9
: 104–106
Hypertension guidelines for type 2 diabetes in South
Africa: consensus and controversies
BRIAN RAYNER
Introduction
H
ypertension is common and integral to the pathophysiology
of type 2 diabetes (T2DM). It affects the majority of patients,
and is an important modifiable risk factor for both micro-
and macrovascular disease.
1
The recent publication of the South African Hypertension
Society guideline (SAHS) 2011
2
and the SEMDSA guideline for the
management of type 2 diabetes
3
affords us the opportunity to
compare the recommendations for treatment of hypertension in
T2DM and consider the consensus and controversies arising from
the publications.
Consensus
Both guidelines are unambiguous on emphasising the importance
of hypertension as a modifiable risk factor in the patient with
T2DM. Blood pressure (BP) reduction is associated with reduction
in both micro- and macrovascular complications. Both guidelines
emphasise the need for correct BP measurement techniques, the
use of combination therapy to achieve the BP goal, use of ACE
inhibitors or ARBs for patients with albuminuria, monitoring of renal
function and the use of furosemide in preference to thiazides if the
estimated glomerular filtration rate (GFR) is reduced. Additionally
neither guidelines advocate
β
-
blockers as part of the first-line
antihypertensive treatment regimen.
Both guidelines also advocate the use of ambulatory BP
monitoring (ABPM) in the assessment of patients, but the SEMDSA
guideline restricts this to patients with suspected white-coat or
office hypertension. The SAHS guideline advocates the use of ABPM
for diagnosis of hypertension, and assessment of white coating,
masking, nocturnal BP and response to treatment.
Controversies
The small differences in the SEMDSA and SAHS guidelines reflect the
current controversies articulated in the wider domain. The important
differences between the guidelines are shown in Table 1.
BP target and the J curve
Several studies have influenced the old adage ‘the lower the better in
type 2 diabetes’. The ‘lower the better’ BP targets and the J curve are
the most controversial issues currently in hypertension literature. In a
critical reappraisal of the European Hypertension Guidelines as far back
as 2009, Mancia
et al
.
questioned the target BP < 130/80 mmHg in
diabetic patients.
4
They concluded that there is a wealth of evidence for
treating BP above 140/90 mmHg, but very little to support targets of
130/80
mmHg. However, the target BP has as yet not been adjusted.
This difference in target is highlighted in the SAHS and SEMDSA
guidelines. The former suggested < 130/80 mmHg and the latter
≤ 140/80 and ≥ 120/70 mmHg. In the 2006 SAHS guideline, a lower
limit of diastolic pressure of 64 mmHg was included, but not in the
current guideline.
The guidelines are in agreement with the diastolic pressure target
of < 80 mmHg, which was based on the secondary analysis of the
HOT study.
5
A systolic target has never been established and was
extrapolated from clinical trials. However the ADVANCE study recently
showed that benefit was achieved down to a target of 134 mmHg.
6
In the ACCORD study, patients were randomised to standard versus
conventional treatment. The average difference in BP in the first year
was 133.5mmHg in the standard- versus 119.3mmHg in the intensive-
treatment group.
7
From the epidemiological perspective there should
have been a marked reduction in cardiovascular (CV) events, but the
actual results showed no benefit in the primary endpoint compared to
standard treatment, albeit with significantly lower stroke rates.
In a recent publication, the results of diabetic and non-diabetic
patientsfromtheONTARGETstudywereanalysed
posthoc
todetermine
the effect of BP on outcome.
8
At all levels of BP, cardiovascular events
were significantly increased in the diabetics. In agreement with the
ACCORD study, the risk of stroke in the diabetic patients continued
to decrease to achieved systolic BP values of 115 mmHg, with no
evidence of an upward J-curve inflection.
In contrast, for the primary outcome (CV death, myocardial
infarction, stroke or hospitalisation for congestive heart failure), the
nadir of the J curve lay at about 129.6 mmHg (122.1–137.0 mmHg)
systolic BP for diabetic patients and 129.0 mmHg (123.9–134.1
mmHg) for non-diabetic patients. Achieving systolic BP of 130 mmHg
instead of 140 mmHg reduced the risk for the primary outcome by
3.4%
in diabetic patients and 4% in non-diabetic patients; for CV
death, 0 and 1.9%, respectively; for myocardial infarction, –3.7 and
0.1%,
respectively; and for stroke, 31.4 and 21.7%, respectively.
For diastolic BP, the primary outcome in both diabetic and non-
diabetic patients showed the highest risk occurred in subjects with
the lowest or highest in-trial diastolic BP (67.2 and 86.7 mmHg,
respectively), whatever the systolic BP values. The increase in risk in
the lowest diastolic BP quartile was even greater in diabetics than
non-diabetics.
In a Cox hazards risk analysis of the subjects with initial systolic
BP < 130 mmHg, after adjusting for the baseline variables, the
Table 1.
Key differences between the SEMDSA and SAHS guidelines.
•
BP target and the J curve
•
Definition of hypertension in the diabetic patient
•
Choice of antihypertensive therapy and combination therapy
•
Hypertension algorithm
