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188 Cardio Diabetes Medicine 2017

Obstructive Sleep Apnoea (OSA):

Cardiodiabetic issues

Professor Ram Dhillon (UK),
London North West Healthcare NHS Trust,
Plymouth University, UK, Medical Director, Rila Institute, London

Abstract parameters during a formal sleep study, either by tra-
There is increasing evidence that there is an associ- ditional polysomnography, which is also a research
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ation between obstructive sleep apnoea (OSA) and tool or now, more commonly, by way of a home
diabetes (Type 2). Furthermore, the association ex- sleep study providing a Tier 3 level study, which for
tends to cardiovascular disease, particularly hyper- clinical purposes is sufficient. An AHI of 5 or less is
tension and most recently a link between OSA and normal, 5-15 episodes are a mild grade OSA, 15-30
an increase in the progression of dementia. episodes a moderate grade OSA and an AHI score
above 30 is severe OSA.
Keywords:
Obstructive sleep apnoea (OSA); Type 2 diabetes; The Cardiometabolic consequences of OSA
cardiovascular disease; dementia The presence of OSA is an independent risk factor
for Cardiovascular Diseases (CVD) . A wide range of
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Introduction CVDs are associated with OSA, including hyperten-
sion and heart failure 10-11 . There is evidence that OSA
It is estimated that up to 4% of the UK population plays a role in the progression of atherosclerosis as
suffer OSA with ~ 2% having severe OSA (1.3 million). it has been associated with an increase in the mark-
Most importantly research suggests an occurrence ers of thrombotic risk, such as platelet activation and
of 40% of individuals with OSA having type 2 Diabe- increased fibrinogen . A linear relationship has been
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1-2
tes . It is predicted that the global burden of type 2 identified between the severity of OSA and preva-
diabetes is expected to rise form the present level of lence of hypertension .
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250 million to 380 million by 2025 . The major cause
of death amongst diabetics is cardiovascular disease The metabolic syndrome is a group of biochemical
and this is compounded by the presence of OSA . and physiological defects that are associated with
4-5
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Other studies have shown a link with the severity of the development of CVD and type 2 diabetes . These
OSA and weight gain , the latter being, in its own defects include central obesity and two additional
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6-7
right, a risk factor for developing type 2 diabetes . abnormalities from raised triglycerides, raised HDL
cholesterol, raised BP and a raised fasting plasma
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Obstructive Sleep Apnoea glucose . In patients with type 2 diabetes these mul-
tiple factors coalesce as the Metabolic Syndrome and
An apnoea is absence or cessation of breathing, for have a synergistic additional risk of CVD compared
a minimum of 10 seconds, which can be due to a to the sum of the individual risk factors .
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central issue (a neurological condition) affecting the
respiratory centre, or by far the commonest disorder There is evidence that also reveal a link between
due to a total obstruction, effectively a strangulation, OSA and cerebrovascular diseases, stroke in partic-
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of the pharyngeal airway. A hypopnoea is a reduced ular . This may be due to the association of OSA with
airflow due to a partial obstruction. Obstructive ap- hypertension, increased progression of atherosclero-
noea is graded according to the total hourly episodes sis and atrial fibrillation. A previous study reported a
of apnoea and hypopnoea per hour, the AHI index. 20% reduction in cerebral blood flow during an ob-
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These can be determined by measuring a variety of structive apnoea .
GCDC 2017