CARDIOVASCULAR JOURNAL OF AFRICA • Vol 24, No 4, May 2013
148
AFRICA
Exercise and fitness in diabetes and
heart disease: when do we reach the
limits?
Carl
Lavie,
John
Ochsner
Heart
and
Vascular
Institute, New Orleans
Cardiorespiratory fitness is graded: low
fitness is defined as the lowest quintile of
individuals assessed according to their time
on the treadmill, adjusted for gender and
age. Small improvements in fitness result
in a significant reduction in incidence of
diabetes and mortality. Physical inactiv-
ity and low fitness increases total mortality
1.7- to two-fold in males. Fitness overrides
fatness as a cause of cardiovascular disease.
There are multiple mechanisms mediat-
ing the effect of fitness. An important factor
is improvement in mood and anxiety. The
exercise dose is important, more not neces-
sarily being better. Resistance training is
important in addition to aerobic exercise; 40
minutes per day of vigorous exercise prob-
ably provides the maximal benefit.
Modern drug therapy for type 2
diabetes: a cardiological perspective
Mansoor Husain, Toronto General Hospital
Research
Institute
The DECODE study showed that IGT
increases mortality risk. HbA
1c
level has
been shown to correlate with macrovascular
disease and heart failure. Reducing HbA
1c
level has not been shown to change this
outcome.
Good glycaemic control improves quali-
ty of life and microvascular disease. A meta-
analysis of sulphonylureas showed that they
increase in mortality 2.5- to three-fold.
There are no convincing data on survival for
any other hypoglycaemic therapy.
GLP-1 is rapidly degraded (2.5 min)
therefore only a small proportion reaches
the heart. GLP metabolites may be the active
substances affecting cardiovascular func-
tion. Experimental evidence has shown that
DPP4 inhibition and GLP1 agonism improve
survival in mice after myocardial infarction
(MI). GLP1 agonism but not DPP4 inhibi-
tion has reduced experimental infarct size.
The Hatter lecture:
Blood pressure control in diabetes:
what are the limits, what are the
drugs and how are they defined?
Morris Brown, University
of Cambridge, UK
Brown discussed the control of hypertension
in diabetics, pointing out that in all hyperten-
sives, the risk for MI is greater than that for
stroke, although the less linear relationship
of blood pressure to stroke makes it easier
to detect changes in the frequency of stroke
than of MI when blood pressure is reduced.
Masked hypertension occurs more frequent-
ly in diabetics and carries a risk equivalent to
that of stage 1 hypertension. Treating blood
pressure to target level in diabetics does
not restore the cardiovascular risk to that of
normotensive (untreated) diabetics.
Brown has found evidence of primary
hyperaldosteronism in hypertensives. This
may be identified by inappropriate suppres-
sion of the renin level. Hypokalaemia is
found less frequently. About 10% of this
group have adrenal micro-adenomas, which
may be identified by PET scanning. Early
identification and excision may cure the
hypertension but is less likely to be effec-
tive in those whose elevated blood pressure
is long standing.
Debate: diabetologist vs cardiologist
The major aim in the therapy of
type 2 diabetes (DM2) lies in limiting
microvascular damage
Steven
Kahn
(diabetologist)
University
of
Washington,
Seattle
The 10-year mortality rate was 40% in
UKPDS. The mortality rate in diabetes was
lower in a high-income group of patients.
In the high-income group, the expenditure
on diabetes far exceeded the expenditure in
middle- and lower-income groups.
Around 50% of all-cause mortality in
diabetes is non-cardiovascular. The combi-
nation of diabetes and chronic kidney disease
(CKD) had an all-cause mortality rate of
30% compared to 7.5% in a group in whom
neither condition was present. Similarly, the
combination of CKD and albuminuria had
a mortality of 47% compared to those with
neither condition.
The 10-year results of UKPDS showed
reductions in both mortality and MI. In the
ACCORD study, although negative overall,
better results were obtained in the subgroups
with albuminuria. The most recent NHANES
report on diabetics found worsening percent-
ages of glycaemic control, blood pressure
control, control of low-density lipoprotein
(LDL) cholesterol and diminishing numbers
on statin therapy, with a very low percent-
age of patients achieving control of all these
parameters.
The major aim in the therapy of DM2
lies in limiting macrovascular damage
Bryan
Williams
(cardiologist),
University
College London
Increased pulse pressure develops with
ageing and begins earlier in diabetes. The
presence of an increased pulse pressure in
diabetes is strongly correlated with mortal-
ity. The pathogenesis involves loss of elas-
tin, collagen deposition and modification
of the collagen by advanced glycation end-
products, which result in cross linkage of
collagen, aortic stiffness, loading of the left
ventricle and a reduced work capacity.
In diabetics there is a loss of the reflected
wave in the aorta with transmission of
pulsatile flow more distally in the peripheral
circulation. This leads to increased pulsatil-
ity in the microcirculation and promotes
microvascular disease. Diabetes differs from
the effects seen in hypertension and ageing
in that autoregulation within the microcircu-
lation is impaired.
Beyond warfarin: are there any limits?
Stefan
Hohnloser,
JW
Goethe
University,
Frankfurt
The results of the RE-LY, ROCKET-AF
and ARISTOTLE trials were reviewed.
Given the reduced stroke risk, diminu-
tion of intracranial bleeding and ease of
use, Hohnloser preferred the use of one
of the novel oral anticoagulants to warfa-
rin, although admitting that cost constraints
were problematic. His preference overrode
considerations of good control of the INR
on warfarin or moderate chronic kidney
injury (GFR 30–60 ml/min).
Debate: Lifestyle changes vs drugs:
which best limits cardiovascular
disease?
Tim
Noakes,
University
of
Cape
Town
and
Peter
Libby,
Brigham
and
Women’s
Hospital, Harvard Medical
School, Boston
The debate between Tim Noakes and Peter
Libby was an excellent closing event, both
arguing well. Noakes proposed that lifestyle
with increased exercise and a low-carbohy-
drate diet could in his view achieve excel-
lent results on general health, including
levels of blood glucose and lipids. Thus drug
therapy could often be avoided. However, no
controlled studies were presented.
Libby agreed that the standard recom-
mended low-fat diet was not the best. He
gave his support to the Mediterranean diet
(fresh vegetables, high fruit intake, fish
rather than meat, and nuts and olive oil).
In the first controlled outcome diet study
ever (
New
Engl
J
Med
, April 2013), the
Mediterranean diet decreased cardiovascu-
lar outcomes and total mortality compared
with a low fat diet. However, Libby argued,
the major problem with any diet was poor
long-term adherence, less than 40% at one
year, so that in clinical practice drug therapy
was more effective.
AJ Dalby, JL Aalbers
