If you suffer from type 2 diabetes or hypertension, you should be evaluated for obstructive sleep apnea by a physician who is board-certified in sleep medicine. This is a recommendation recently issued for the first time by the American Academy of Sleep Medicine. This new guideline could have a significant impact on diagnostic procedures for tens of millions of adults in the United States. Type 2 diabetes and hypertension are all-too-common conditions among U.S. adults, and their numbers are rising alarmingly. More than 25 million people in the U.S. have diabetes, and approximately 90 to 95% of these are cases of type 2 diabetes. Hypertension—high blood pressure—affects a third of American adults, roughly 67 million people.
OSA frequently is found in people with type 2 diabetes and with cardiovascular conditions, including hypertension. Estimates vary, but it is believed that approximately half of patients with high blood pressure also have obstructive sleep apnea. The overlap may be even higher with type 2 diabetes, with a majority of these patients also suffering from the sleep disorder.
There is an enormous body of research to suggest that people who suffer from OSA are at significantly increased risk for diabetes and hypertension, and vice versa. The relationships of OSA to diabetes and hypertension are complicated and appear to be multi-directional. All three conditions share risk factors, particularly obesity. In addition to exploring the consequences of shared risk factors, scientists are also investigating other biological connections between sleep apnea, hypertension and type 2 diabetes. We don’t know all of the connections between these three health issues, but we do know that in the cases of both type 2 diabetes and hypertension, the presence of obstructive sleep apnea is extremely common and can complicate treatment if left unattended. OSA, like many sleep disorders, continues to be seriously under-diagnosed. Those with un-diagnosed sleep apnea are at particular risk for complications of diabetes and hypertension.
The Sleep Heart Health Study is a long-term, ongoing, population-based investigation of the health consequences of sleep-disordered breathing on cardiovascular health. This research has revealed a strong association between the disordered breathing that is a symptom of sleep apnea and hypertension. The results are striking in particular because they indicate the risks of OSA to high blood pressure are not limited to traditional high-risk groups such as the obese, men, and older adults. Instead, the study has found elevated risk for high blood pressure among middle aged and older adults, men and women, people who are overweight and those who are normal weight. Other recent research has also demonstrated the relationship between OSA and high blood pressure:
- The risk of hypertension appears to increase with the severity of obstructive sleep apnea. Researchers at the University of Wisconsin School of Medicine analyzed data on sleep and blood pressure for 709 adults over a 4-year period. They found the risk of hypertension increased with the frequency of apnea episodes per hour of sleep. Those with 15 or more apnea episodes per hour were at 3 times the risk for hypertension as those without sleep apnea.
- Severe OSA has also been strongly linked to resistant hypertension. Resistant hypertension is a form of high blood pressure that does not respond to medication. When a group of men and women with resistant hypertension were tested for obstructive sleep apnea, researchers found 83% had the sleep disorder.
Attempting to treat high blood pressure through medications or other therapies without also addressing the possible presence of OSA may undermine the success of treatment.
The same likely is true for Type 2 diabetes. Research has established links between obstructive sleep apnea and diabetes, which have been described as “interacting epidemics.” Studies indicate that OSA may disrupt normal glucose metabolism and increase insulin resistance, which is the underlying biological mechanism of type 2 diabetes:
- Researchers at the University of Chicago found the presence of OSA in patients with type 2 diabetes was linked to a decline in glucose control. Compared to diabetes patients without obstructive sleep apnea, those with mild, moderate, and severe sleep apnea demonstrated poorer glucose control. As severity of OSA increased, glucose control in these patients deteriorated significantly.
- Obesity is an important risk factor for both obstructive sleep apnea and type 2 diabetes. But research indicates that a relationship between the two conditions may exist independent of obesity. Researchers at Penn State University found an association between insulin resistance and sleep apnea in a group of non-obese middle-aged men.
There’s some good news behind this AASM recommendation as well. In both hypertension and type 2 diabetes patients with OSA, treatment for sleep apnea can not only improve the sleep disorder, but also help improve the other conditions as well. Research shows that effectively treating OSA can lead to improvements in hypertension and type 2 diabetes:
- Regular use of CPAP, the most common treatment for OSA, appears to play a role in lowering glucose levels, according to new research from the University of Chicago’s Sleep, Metabolism and Health Center. Patients with both sleep apnea and type 2 diabetes who used CPAP continuously for 1 week lowered both their daily average glucose levels and their morning glucose levels. (Morning spikes in glucose levels are common among those with type 2 diabetes.)
- CPAP also can help reduce both nocturnal and daytime blood pressure in patients with obstructive sleep apnea. A single night of CPAP use resulted in a reduction of nighttime systolic blood pressure, and 2 months of sustained CPAP lowered daytime systolic blood pressure as well. Other research has shown that 12 weeks of CPAP therapy resulted in lowered daily blood pressure values.
This recommendation by the AASM makes a great deal of sense, based on the abundance of evidence we have linking these conditions and the complications we know can arise when sleep apnea is left untreated. Now it is up to patients and doctors to follow through and make sure these evaluations take place, with qualified physicians. If you are one of the millions who suffer from either type 2 diabetes or hypertension, your can improve your health and lower your risks if you are properly evaluated for obstructive sleep apnea.
Michael J. Breus, PhD
The Sleep Doctor™