OBSTRUCTIVE SLEEP APNEA AND IMPAIRED GLUCOSE REGULATION

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The purpose of this study is to learn whether obstructive sleep apnea (OSA), a condition in which breathing is affected during sleep, can cause abnormal blood sugar (glucose) processing, which could lead to diabetes, or pre-diabetic conditions. In addition, both OSA and diabetes are linked to autonomic dysfunction of the parasympathetic and sympathetic nervous system, which controls heart rate and blood pressure. It is unclear whether the autonomic dysfunction found in OSA is due to diabetic or pre-diabetic conditions, or whether it caused by OSA independently. OSA and diabetes are commonly found in overweight individuals and both can cause increased risk of heart disease and strokes. Autonomic dysfunction is thought to increase the risk of heart disease in both of these conditions. OSA is a treatable condition, utilizing nasal continuous positive airway pressure (CPAP), which blows air into the nose, overcoming the obstruction to airflow that occurs in OSA. During this study, subjects identified by their doctors as having symptoms of OSA and referred for a sleep study (polysomnogram or PSG) will be asked to participate in this study. Patients will undergo a PSG to determine whether they have OSA. The following morning, patients will be asked to undergo a glucose tolerance test (OGTT) in which blood is taken before and after drinking a sugary drink. Several tests of the autonomic system will be performed. Patients who are diagnosed with OSA will be brought back to the sleep lab to determine what kind of CPAP is needed for their treatment and given a prescription. After 6 months, patients will be asked to return for a second OGTT and repeat autonomic tests. By performing this study, we hope to learn whether patients with OSA have an increased prevalence of diabetes or pre-diabetic condition, characterize the autonomic dysfunction associated with these disorders, and determine whether nasal CPAP will improve glucose metabolism and/or autonomic function in people who do have abnormal processing of blood sugar.