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Obstructive sleep apnea (OSA) increasingly linked to type 2 diabetes
| Author: Timothy J. McGee DO, FCCP, ABSM |
| Article Date: 4/15/2008 |
It is well-established that obstructive sleep apnea (OSA) is common among patients with type 2 diabetes. Research has shown that 50% of male patients with diabetes suffer from sleep apnea.1,2 Increasingly researchers are documenting the specific mechanisms that link diabetes with OSA. Studies demonstrate an independent association between OSA and both insulin resistance and glucose intolerance.3,4 While both type 2 diabetes and OSA are most often associated with obesity, one study has also demonstrated a relationship between sleep apnea and glucose-insulin metabolism irrespective of age or obesity.5 The purpose of this article is to examine in more detail recent studies related to the effects of OSA on diabetic patients and the link of continuous positive airway pressure (CPAP) treatment to the amelioration of some diabetic symptoms. Based on this growing body of evidence it is clear that all patients newly diagnosed or continuing with treatment for type 2 diabetes should be screened for sleep apnea as a matter of standard practice.
What is sleep apnea?Ê
Obstructive sleep apnea (OSA) is a condition in which patients stop breathing for 10 seconds or more during sleep, sometimes hundreds of times in a night. Studies indicate that one in five adults suffer from sleep apneas, ranging in severity from mild to potentially lethal.6 Approximately one quarter of men and one in ten women are affected by some form of sleep-disordered breathing (SDB), of which OSA is the most common. OSA increases in prevalence with the age of the patient; some degree of breathing cessation is experienced during sleep by nearly one-third of men between the ages of 50 and 60.7 In spite of its prevalence as a condition, studies indicate that as many as 80% of those suffering from SDB go undiagnosed. 6 Ê Common signs and symptoms of sleep apnea include:
Obesity
Snoring
Excessive daytime sleepiness
Neck size of greater 17 in for males, 16 in for females
Morning headaches
Hypertension
Poor motivation
Memory loss/difficulty concentrating Ð decreased cognitive functioning
Depression
As the above symptoms suggest, OSA can lead to decreased productivity at work and in the home, as well as a loss of general quality of life. But even more troubling from a public health perspective, OSA has demonstrated links with other serious health risks. Comorbidities for OSA include heart disease, high blood pressure, stroke, and obesity.8-13 Diabetes is also a comorbidity, and several recent studies increasingly indicate not only the link between diabetes symptoms and OSA, but the positive effects of CPAP treatment in reducing some of these symptoms.
Studies Detail Mechanisms Linking OSA and Diabetes
Over the last several years a number of important medical studies have contributed to our understanding of the relationship between the treatment of OSA and diabetes.
In 2003, researchers at the University Turin found evidence that OSA impairs insulin sensitivity in obese patients. In this study of nearly 60 obese patients, approximately half of whom suffered from OSA, researchers found that the obese patients also suffering from OSA were markedly less sensitive to insulin that the patients with simple obesity, regardless of adiposity. Researchers concluded that this worsening in insulin sensitivity in OSA patients likely accounts for the increases vascular risk in these patients as opposed to those suffering from obesity alone. 14
Following upon this discovery researchers in Germany found in 2004 that CPAP treatment rapidly improves insulin sensitivity in patients with OSA. The study measured insulin sensitivity in 40 patients after 2 days of CPAP therapy and then again after 3 months of uninterrupted continual therapy. The study found a significant increase in insulin sensitivity in subjects after only 2 days of treatment. That increase was also found to have been sustained after 3 months of continuous CPAP usage. This study led researchers to conclude that sleep apnea is an independent risk factor for increasing insulin resistance. 15
Another study has found impaired glucose homeostasis to be related to SDB. The study demonstrated that initiating CPAP treatment improved glycemic control in a group of 24 very obese patients with type 2 diabetes. Based upon this results the researchers suggest that CPAP can be an important therapeutic approach for diabetics with SDB. 16
An important study from 2007 documents the widespread prevalence of OSA in the population of adults with type 2 diabetes. In this study of 279 diabetic patients, nearly 50% were found to suffer from OSA as well. The study also identified factors that may be associated with its presence in the population, including male sex, an age of 62 years or older, obesity, snoring, and reports of breathing cessation during sleep. As a result of the study the researchers recommended that screening for OSA be considered for all patients with type 2 diabetes. 1
Finally, a recently completed study further documents a clear role for slow-wave sleep (SWS) in the maintenance of glucose homeostasis. The study found a remarkably consistent 25% decrease of insulin sensitivity by in a population of young, lean males after three nights of suppressed SWS. This change in insulin sensitivity is comparable to that associated with a bodily weight increase of 8-13kg. This decrease leads to a reduced glucose tolerance and an increased risk of diabetes. The data suggests that reduced sleep quality with low levels of SWS may contribute to an increased risk of diabetes in aging and obese patients. 17
This date provides abundant evidence that physicians treating patients with type 2 diabetes should make a standard practice of screening these patients for OSA.
Screening for Sleep Apnea and Making a ReferralÊ
A number of simple and cost-effective screening methods for OSA are readily available to physicians. Simple questionnaires such as the Epworth Sleepiness Scale (ESS) or the Berlin Questionnaire as well as portable sleep screeners and pulse oximetry are all common screening methods. Sleep-screening questions can even be added to patient history questionnaires as a routine form of screening before the patient sees the physician. When a patient screens positive for SDB via one of these methods, they should be referred to a sleep lab where they will undergo a polysomnography test (PSG).
A variety of treatments exist for those diagnosed with OSA at the sleep lab. However, CPAP is the gold standard treatment of OSA. A wide variety of CPAP devices exist to provide customized therapy for the individual needs of all patients.Ê
ConclusionÊ
The growth in recent clinical data documenting the link between CPAP treatment and the decrease in symptoms of type 2 diabetes is a clear indication that treatment for diabetes and OSA should go hand in hand. Longstanding data suggesting the under diagnosis of SDB and the linking of SDB to a number of serious health risks reinforces the importance of screening every patient for OSA. In particular, with relation to diabetes, evidence is now abundant that treatment improves glycemic control. In light of this evidence, and considering the simplicity and availability of objective and cost-effective screening methods, it appears advisable for physicians to make screening for OSA a standard practice whenever a patient is diagnosed with type 2 diabetes.
Einhorn et al Endocr Pract 2007
Resnick et al Diabetes Care 2003
Punjabi et al Am Journ Ep 2004
Punjabi et al Am Journ Resp Crit Care Med 2002
Meslier et al European Resp Journ 2003
Young el al Am Journ Resp Crit Care 2002
Young et al NEJM 1993
Javaheri et al. Circulation 1999Ê
Schafer et al. Cardiology 1999Ê
Somers et al. Circulation 2004Ê
Sjostrom et al. Thorax 2002Ê
OÕKeeffe & Patterson. Obes Surgery 2004Ê
Yaggi. NEJM 2005Ê
Tassone et al Clin End 2003
Harsch et al Am Journ Resp Crit Care Med 2004
Babu et al Arch Intern Med 2005
Tasali et al PNAS
What is sleep apnea?Ê
Obstructive sleep apnea (OSA) is a condition in which patients stop breathing for 10 seconds or more during sleep, sometimes hundreds of times in a night. Studies indicate that one in five adults suffer from sleep apneas, ranging in severity from mild to potentially lethal.6 Approximately one quarter of men and one in ten women are affected by some form of sleep-disordered breathing (SDB), of which OSA is the most common. OSA increases in prevalence with the age of the patient; some degree of breathing cessation is experienced during sleep by nearly one-third of men between the ages of 50 and 60.7 In spite of its prevalence as a condition, studies indicate that as many as 80% of those suffering from SDB go undiagnosed. 6 Ê Common signs and symptoms of sleep apnea include:
Obesity
Snoring
Excessive daytime sleepiness
Neck size of greater 17 in for males, 16 in for females
Morning headaches
Hypertension
Poor motivation
Memory loss/difficulty concentrating Ð decreased cognitive functioning
Depression
As the above symptoms suggest, OSA can lead to decreased productivity at work and in the home, as well as a loss of general quality of life. But even more troubling from a public health perspective, OSA has demonstrated links with other serious health risks. Comorbidities for OSA include heart disease, high blood pressure, stroke, and obesity.8-13 Diabetes is also a comorbidity, and several recent studies increasingly indicate not only the link between diabetes symptoms and OSA, but the positive effects of CPAP treatment in reducing some of these symptoms.
Studies Detail Mechanisms Linking OSA and Diabetes
Over the last several years a number of important medical studies have contributed to our understanding of the relationship between the treatment of OSA and diabetes.
In 2003, researchers at the University Turin found evidence that OSA impairs insulin sensitivity in obese patients. In this study of nearly 60 obese patients, approximately half of whom suffered from OSA, researchers found that the obese patients also suffering from OSA were markedly less sensitive to insulin that the patients with simple obesity, regardless of adiposity. Researchers concluded that this worsening in insulin sensitivity in OSA patients likely accounts for the increases vascular risk in these patients as opposed to those suffering from obesity alone. 14
Following upon this discovery researchers in Germany found in 2004 that CPAP treatment rapidly improves insulin sensitivity in patients with OSA. The study measured insulin sensitivity in 40 patients after 2 days of CPAP therapy and then again after 3 months of uninterrupted continual therapy. The study found a significant increase in insulin sensitivity in subjects after only 2 days of treatment. That increase was also found to have been sustained after 3 months of continuous CPAP usage. This study led researchers to conclude that sleep apnea is an independent risk factor for increasing insulin resistance. 15
Another study has found impaired glucose homeostasis to be related to SDB. The study demonstrated that initiating CPAP treatment improved glycemic control in a group of 24 very obese patients with type 2 diabetes. Based upon this results the researchers suggest that CPAP can be an important therapeutic approach for diabetics with SDB. 16
An important study from 2007 documents the widespread prevalence of OSA in the population of adults with type 2 diabetes. In this study of 279 diabetic patients, nearly 50% were found to suffer from OSA as well. The study also identified factors that may be associated with its presence in the population, including male sex, an age of 62 years or older, obesity, snoring, and reports of breathing cessation during sleep. As a result of the study the researchers recommended that screening for OSA be considered for all patients with type 2 diabetes. 1
Finally, a recently completed study further documents a clear role for slow-wave sleep (SWS) in the maintenance of glucose homeostasis. The study found a remarkably consistent 25% decrease of insulin sensitivity by in a population of young, lean males after three nights of suppressed SWS. This change in insulin sensitivity is comparable to that associated with a bodily weight increase of 8-13kg. This decrease leads to a reduced glucose tolerance and an increased risk of diabetes. The data suggests that reduced sleep quality with low levels of SWS may contribute to an increased risk of diabetes in aging and obese patients. 17
This date provides abundant evidence that physicians treating patients with type 2 diabetes should make a standard practice of screening these patients for OSA.
Screening for Sleep Apnea and Making a ReferralÊ
A number of simple and cost-effective screening methods for OSA are readily available to physicians. Simple questionnaires such as the Epworth Sleepiness Scale (ESS) or the Berlin Questionnaire as well as portable sleep screeners and pulse oximetry are all common screening methods. Sleep-screening questions can even be added to patient history questionnaires as a routine form of screening before the patient sees the physician. When a patient screens positive for SDB via one of these methods, they should be referred to a sleep lab where they will undergo a polysomnography test (PSG).
A variety of treatments exist for those diagnosed with OSA at the sleep lab. However, CPAP is the gold standard treatment of OSA. A wide variety of CPAP devices exist to provide customized therapy for the individual needs of all patients.Ê
ConclusionÊ
The growth in recent clinical data documenting the link between CPAP treatment and the decrease in symptoms of type 2 diabetes is a clear indication that treatment for diabetes and OSA should go hand in hand. Longstanding data suggesting the under diagnosis of SDB and the linking of SDB to a number of serious health risks reinforces the importance of screening every patient for OSA. In particular, with relation to diabetes, evidence is now abundant that treatment improves glycemic control. In light of this evidence, and considering the simplicity and availability of objective and cost-effective screening methods, it appears advisable for physicians to make screening for OSA a standard practice whenever a patient is diagnosed with type 2 diabetes.
Einhorn et al Endocr Pract 2007
Resnick et al Diabetes Care 2003
Punjabi et al Am Journ Ep 2004
Punjabi et al Am Journ Resp Crit Care Med 2002
Meslier et al European Resp Journ 2003
Young el al Am Journ Resp Crit Care 2002
Young et al NEJM 1993
Javaheri et al. Circulation 1999Ê
Schafer et al. Cardiology 1999Ê
Somers et al. Circulation 2004Ê
Sjostrom et al. Thorax 2002Ê
OÕKeeffe & Patterson. Obes Surgery 2004Ê
Yaggi. NEJM 2005Ê
Tassone et al Clin End 2003
Harsch et al Am Journ Resp Crit Care Med 2004
Babu et al Arch Intern Med 2005
Tasali et al PNAS