heart disease and diabetes
The nighttime breathing disorder known as sleep apnea increases a person's risk of having a heart attack or of dying by 30% over a period of four to five years, according to a Yale School of Medicine study.
These findings and another Yale study linking sleep apnea and diabetes were presented in May at the American Thoracic Society 2007 International Conference in San Francisco.
In obstructive sleep apnea, the upper airway narrows, or collapses, during sleep. Periods of apnea end with a brief partial arousal that may disrupt sleep hundreds of times a night. Obesity is a major risk factor for sleep apnea.
Sleep apnea triggers the body's "fight or flight" mechanism, which decreases the amount of blood pumped to the heart, says Dr. Neomi Shah, clinical fellow in the Department of Internal Medicine, pulmonary section. She conducted the study linking heart disease and sleep apnea.
Shah's study included 1,123 patients referred for sleep apnea evaluation. They were followed for the next four to five years to see how many had a heart attack, coronary angiography, bypass surgery or died. Previous studies showed a correlation between sleep apnea and heart disease, but this is the first large study to follow patients for five years and to adjust the findings for other traditional risk factors for heart disease.
The most effective treatment for sleep apnea is a technique called nasal CPAP (continuous positive airway pressure), which delivers air through a mask while the patient sleeps, keeping the airway open. "There is some evidence to make us believe that when sleep apnea is appropriately treated, the risk of heart disease can be lowered," Shah says.
In another Yale study presented at the conference, researchers found patients with sleep apnea are at increased risk for developing Type II diabetes, independent of other risk factors. The study looked at 593 patients at the VA Connecticut Healthcare System referred for evaluation of sleep-disordered breathing.
The researchers followed the patients for up to six years and found that patients diagnosed with sleep apnea had more than 21Ž2 times the risk of developing diabetes compared with those without the nighttime breathing disorder. The more severe a patient's sleep apnea, the greater the risk of developing diabetes.
Dr. Nader Botros, a fellow in Yale's pulmonary section, says the exact reasons for the link between sleep apnea and diabetes are not known, but researchers suspect that when the "fight or flight" response is triggered by sleep apnea, a cascade of events occurs, including the production of high levels of the hormone cortisol that ultimately leads to insulin resistance and glucose intolerance. These are pre-diabetic conditions that, if left untreated, can lead to the development of diabetes. Low oxygen levels also appear to play an important role.
"The impact of diabetes on public health is great," Botros says. "Diet and exercise, along with a medication regimen, are the mainstays of treatment, but unfortunately diabetes remains a major public health challenge. New approaches are needed to better understand the risk factors for diabetes. Understanding the link between sleep-disordered breathing and diabetes may represent one such approach."
-- By Jacqueline Weaver
T H I S
W E E K ' SS T O R I E S
Yale to increase medical and scientific research programs
with acquisition of the Bayer HealthCare complex
Acquisition to expand Yale's economic impact
Milestones in building Yale's medical and scientific research strength
Study shows stem cells curb Parkinson's disease in primatesChina proves 'a great joy' for Yale 'friends from afar'
COMMENCEMENT 2007
With pomp, Yale celebrates its newest graduates
Baccalaureate Address
Honorary Degrees
Outstanding teachers and students are awarded prizes
Former Yale gallery director has been elected an alumni fellow
NASA administrator is appointed University's first CFO
'Lights, cameras and action!' come to campus
Delegations travel to Brazil and Mexico for alumni-hosted events
Initiative seeks to promote effective use of solar power
Air pollution is shown to harm pregnant woman
SCHOOL OF MEDICINE NEWS
Sleep apnea is linked to heart disease and diabetes
Research findings on FMRP protein may lead to . . .
Residents' work-hour reductions not harmful to patients, study says
New radio show offers information, support to cancer patients
Scientific symposium will honor renowned faculty member
Students' research on wood frogs is featured in Peabody exhibit
In Memoriam: Naturalist Charles L. Remington
Performances will showcase talents of young playwrights
New Yale website illustrates the history of slavery in Connecticut
Campus Notes
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