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OBSTRUCTIVE SLEEP APNEA AND TYPE 2 DIABETES
By Barbara Richard, BHS(RT), RPSGT, RRT
O
bstructive sleep apnea (OSA) and type 2 diabetes are twin epidemics that are occurring in North America right now. How
are these diseases linked? Does one cause the other, or do they just
exacerbate each other? These questions will be explored and the
impact of OSA on diabetic patients will be discussed in this article.
Age > 40
Overweight
Race: Aboriginal
Native American
maintaining a healthy weight.
Some may require medications
such as insulin.
THE COMMON LINK
Both OSA and type 2 diabetes
are highly prevalent in the
Asian
general population. The highest
South Asian
risk factor for both diseases is
obesity with a high central-fat
African decent
distribution – a big belly. Obesity
Native Hawaiians
rates have increased three-fold or
Family History
more since 1980 in some parts of
Increased blood pressure
North America. The explanation
for this increase is quite simple:
Increased Cholesterol
We are consuming more energyGestational Diabetes
dense, nutrient-poor foods that
Gave birth to baby > 9 lbs
are high in sugar and saturated
fats, and we are getting less
FIGURE 1. RISK FACTORS FOR
physical activity.3 This means that
TYPE 2 DIABETES.
we are taking in more calories
than our bodies are working off. The obesity epidemic is the driving
force behind the surge in OSA and type 2 diabetes. Recent studies
suggest that OSA and type 2 diabetes frequently coexist and may
actually exacerbate each other.
Latino
OBSTRUCTIVE SLEEP APNEA
Obstructive sleep apnea (OSA) is characterized by recurrent
episodes of upper airway collapse and obstruction during sleep.
These episodes of obstruction are associated with recurrent oxyhemoglobin desaturation and arousals from sleep. The prevalence
of OSA in the U.S. is currently estimated to be between 5 percent
and 10 percent. Some of the risk factors for OSA are obesity, large
neck circumference, anatomic abnormalities (such as a receding
chin), enlarged tonsils and adenoids, and a family history of OSA.
Symptoms of OSA include loud snoring, choking or gasping during sleep, excessive daytime sleepiness, early morning headaches,
inability to concentrate, memory loss and depression.
TYPE 2 DIABETES
Type 2 diabetes is a disease in which the pancreas does not produce enough insulin, or the body is resistant to the effects of insulin.
The body derives energy by making glucose (i.e., sugar) from food.
To use this glucose the body needs insulin, which is a hormone that
helps the body control the level of glucose in the blood. If someone
has type 2 diabetes, glucose builds up in the blood instead of getting into the cells and being used for energy. Type 2 diabetes is one
of the fastest-growing diseases around the world. Approximately
85 percent of people who have diabetes have type 2 diabetes. It
is estimated that more than 20 million North Americans have
diabetes, and of those affected about one third are unaware that
they have the disease.1 Eighty percent of type 2 diabetes cases can
be attributed to lifestyle. Figure 1 shows common risk factors for
type 2 diabetes.
Some of the symptoms of diabetes are unusual thirst, frequent
urination, weight change (either gain or loss), extreme fatigue or
lack of energy, blurred vision, frequent or recurring infections, and
tingling or numbness in the hands or feet. Type 2 diabetes can
remain undetected for many years as people may show no symptoms. The diagnosis often is made from associated complications or
through an abnormal blood or urine glucose test.2
People with diabetes can live a long and healthy life by keeping
their blood glucose levels in a target range. This can be done by eating healthy meals and snacks, enjoying regular physical activity and
BARBARA RICHARD, BHS(RT),
RPSGT, RRT
Barbara Richard, BHS(RT), RPSGT, RRT,
has been in the sleep field since 2005
and is a sleep technologist for Atlantic
Sleep Centre at Saint John Regional
Hospital in Saint John, New Brunswick,
Canada.
DOES DIABETES CAUSE OSA?
Research that examined diabetes as a cause of sleep apnea
suggests that the mechanism responsible is autonomic neuropathy, which results in dysfunction of the central respiratory motor
control of the diaphragm and decreased ability of the upper airway
to maintain patency during sleep. It was found that OSA was more
prevalent in diabetic patients with autonomic neuropathy than
in control patients who had diabetes without autonomic disturbances.4
DOES OSA CAUSE DIABETES?
There is increased evidence that sleep disturbances negatively
affect glucose metabolism. One study found that those with an
apnea-hypopnea index (AHI) of five or more had twice the risk
of having impaired or diabetic glucose. It further found that the
impairment in glucose tolerance was related to the severity of
oxygen desaturation during the episodes.5 Other studies found that
the cause of glucose intolerance and increased insulin resistance in
persons with OSA is the repetitive episodes of hypoxia and sleep
fragmentation that occur in OSA. Tumor necrosis factor-alpha
(TNF-alpha) and interleukin-6 (IL-6) are groups of proteins
that send out chemical signals. Overproduction of them has been
implicated in a variety of human diseases. TNF-alpha and IL-6
work together to increase insulin resistance. It was found that the
primary determinant for IL-6 levels was body mass index (BMI),
and the main factor influencing TNF-alpha values was severity of
OSA. It also was found that obese subjects with OSA had higher
plasma levels of IL-6 and TNF-alpha than obese subjects without
OSA.7
A2Zzz 19.2 | June 2010
19
Also of interest is a study showing that a healthy person easily can become a diabetic. The study involved 11 healthy, young,
male volunteers whose sleep was restricted to four hours per night.
After only six nights of sleep restriction their sympathetic nervous
system activity was increased and glucose tolerance was impaired.8
ing both CPAP and weight management could be implemented.
Similarly, sleep centers can easily screen OSA patients for type
2 diabetes. Screening tests include: waist measurement, blood
pressure measurement and fasting lipids and glucose followed by a
glucose tolerance test where applicable.
CPAP AND DIABETES
CONCLUSION
More research is needed to study the effect of continuous positive airway pressure (CPAP) therapy on diabetes. The effects of
CPAP therapy on glucose control in subjects with OSA and type
2 diabetes have been inconsistent, but most of these studies did not
take into account CPAP compliance. One study that did consider
compliance found that subjects who used CPAP for more than four
hours per night had reduced post-meal glucose levels compared
with people who used CPAP for less than four hours per night. The
authors of this study believed that the failure to account for poor
compliance may have masked a positive treatment effect of CPAP
in previous studies of diabetic subjects with OSA. They also concluded that treatment of significant OSA in patients with impaired
glucose tolerance, or impaired fasting glucose levels, might prevent,
or delay the progression of, diabetes.8 Poor compliance with CPAP
may cause poor compliance with diabetic treatment.
More research is needed on the link between OSA and type
2 diabetes, and how CPAP affects diabetes. If the AHI can be
lowered and oxygen desaturation and sleep fragmentation avoided,
this will normalize blood glucose levels. Clinicians must consider
the possible diagnosis of OSA in patients with type 2 diabetes. As
sleep professionals it is our responsibility to educate our patients
on the risks associated with OSA and diabetes and to encourage
weight loss management and CPAP compliance. Billions of health
care dollars are spent every year on diabetes and OSA. For many of
these patients these diseases can be prevented. We must remember
that restful and regular sleep is just as important to our health as
regular exercise and a balanced diet.
REFERENCES
1. World Health Organization. Facts and figures [Internet].
Geneva (Switzerland): WHO Diabetes Programme; c2010.
Available from: http://www.who.int/diabetes/facts/en/.
2. Canadian Diabetes Association. What is diabetes? [Internet].
Toronto, Ontarion (Canada): CDA; c2005-2010. Available
from: http://www.diabetes.ca/about-diabetes/what/.
3. World Health Organization. Obesity and overweight [Internet]. Geneva (Switzerland): WHO Global strategy on diet,
physical activity and health; c2010. Available from: http://
www.who.int/dietphysicalactivity/publications/facts/obesity/
en.
4. Chasens ER. Obstructive sleep apnea, daytime sleepiness, and
type 2 diabetes. Diabetes Educ. 2007 May-Jun;33(3):475-82.
5. Collop N. The effect of obstructive sleep apnea on chronic
medical conditions. Cleve Clin J Med. 2007 Jan;74(1):72-8.
6. Punjabi NM, Polotsky VY. Disorders of glucose metabolism
in sleep apnea. J Appl Physiol. 2005 Nov;99(5):1998-2007.
7. Spiegel K, Leproult R, Van Cauter E. Impact of sleep debt
on metabolic and endocrine function. Lancet. 1999 Oct
23;354(9188):1435-9.
8. Babu AR, Herdegen J, Fogelfeld L, Shott S, Mazzone T. Type
2 diabetes, glycemic control, and continuous positive airway
pressure in obstructive sleep apnea. Arch Intern Med. 2005
Feb 28;165(4):447-52.
9. Chasens ER, Olshansky E. Daytime sleepiness, diabetes, and
psychological well-being. Issues Ment Health Nurs. 2008
Oct;29(10):1134-50.
DAYTIME SLEEPINESS & DIABETES
A qualitative study asked people with type 2 diabetes what it
was like to attempt to manage their chronic disease while struggling with sleepiness. Results show that sleepiness was a daily
burden that affected their memory to take medications and check
their blood sugar levels. It also affected their motivation to prepare
healthy meals and exercise. The study also found that their mood
was affected, which had a negative impact on their relationship
with family and friends.9 The daytime effects of untreated OSA can
hinder the effective self management of type 2 diabetes.
IDF CONSENSUS STATEMENT
The International Diabetes Federation (IDF) comprises associations from more than 160 countries. In June 2008 the IDF released
a consensus statement concluding that all type 2 diabetes patients
with symptoms of sleep disordered breathing (SDB) should be
screened for OSA, and that all OSA patients should be screened
for diabetes.10
A MODEL PARTNERSHIP
It is our responsibility as sleep professionals to get this information out to both diabetic patients and physicians. One approach
would be to work in collaboration with other specialists. For
example, the sleep center where I work has formed a successful
partnership with the Heart Failure Clinic at our hospital. We assisted the Heart Failure Clinic in the development of sleep-related
questionnaires, and they now screen their patients through questionnaires and symptom checklists. Patients who are found to be at
risk for OSA are referred to our sleep center for follow up. First we
conduct a type 3 unattended portable monitoring study, and then
the patients receive a consultation with one of our sleep physicians.
A similar approach could be taken with diabetic teaching clinics.
A simple questionnaire, such as the Berlin Questionnaire, could
help screen the patients for OSA. Those who are found to be at risk
for OSA could be referred to a sleep center or local hospital for a
sleep study. If OSA is confirmed, then a treatment regimen includ-
10. Shaw JE, Punjabi NM, Wilding JP, Alberti KG, Zimmet
PZ. Sleep-disordered breathing and type 2 diabetes: a report
from the International Diabetes Federation Taskforce on
Epidemiology and Prevention. Diabetes Res Clin Pract. 2008
Jul;81(1):2-12. Available from: http://www.idf.org/webdata/
docs/DRCP%2081(1)%20Shaw%20et%20al.pdf. 
A2Zzz 19.2 | June 2010