Effects of Treatment of Sleep Apnea on Metabolic Syndrome

Phase 2

Completed

Interventions: Device: Continuous Positive Airway Pressure (CPAP) (Philips-Respironics RemStar Pro® CPAP)
Device: Sham-Continuous Positive Airway Pressure (CPAP) (Philips-Respironics)

Brief Summary: The investigators performed a randomized, cross-over controlled clinical trial comparing 8 weeks of Continuous Positive Airway Pressure (CPAP) to 8 weeks of sham-CPAP in patients with moderate to severe Sleep Disordered Breathing (SDB) and impaired glucose tolerance. A rigorous assessment of metabolic responses to SDB treatment in this group is of great clinical significance because this sample is at high risk for developing diabetes. The paradigm shift of CPAP as a mode of prevention can affect clinical practice in the fields of both primary care and sleep medicine.

Detailed Description: There are few controlled studies that address whether treatment of sleep apnea improves glucose tolerance. This is a randomized, double-blind cross-over study of subjects with sleep apnea (apnea hypopnea index \> 15) and impaired glucose tolerance. Subjects will be randomized to 8 weeks of Continuous Positive Airway Pressure (CPAP) or sham-CPAP, followed by the alternate therapy after a one month wash-out. After each treatment, subjects will undergo 2-hour oral glucose tolerance testing, polysomnography, actigraphy, and measurements of indices of glucose control. The investigators intend to analyze the changes in glucose metabolism and insulin sensitivity in patients with sleep apnea with CPAP intervention.

Recruitment & Eligibility

Inclusion Criteria

moderate to severe Sleep Disordered Breathing (SDB) defined by an Apnea Hypopnea Index (AHI) > 15
had evidence of Impaired Glucose Tolerance (IGT) defined by the mean 2-hour Oral Glucose Tolerance Test (OGTT) glucose of > 140 mg/dl calculated from the two 2-hour OGTTs performed within 3 days of each other

Exclusion Criteria

Not provided

Arm && Interventions

Group	Intervention	Description
Continuous Positive Airway Pressure (CPAP)	Continuous Positive Airway Pressure (CPAP) (Philips-Respironics RemStar Pro® CPAP)	-
Sham-Continuous Positive Airway Pressure (CPAP)	Sham-Continuous Positive Airway Pressure (CPAP) (Philips-Respironics)	-

Primary Outcome Measures

Name	Time	Method
Number of Subjects With Normalization of Impaired Glucose Tolerance (IGT)	20 weeks	Number of subjects who experienced normalization of the mean 2-hour oral glucose tolerance test (OGTT) in the overall sample undergoing therapeutic CPAP vs. sham CPAP. (2-hour OGTT glucose\< 140 mg/dL)

Secondary Outcome Measures

Name	Time	Method
Mean and Standard Deviation of Insulin Indices After Therapeutic CPAP vs. Sham	20 weeks	The data for fasting and 2 hour Insulin (iIU/dL) are presented according to therapeutic CPAP vs. Sham CPAP.
Mean and Standard Deviation of Indices of Insulin Resistance With Therapeutic CPAP vs. Sham	20 weeks	Homeostasis Model Assessment-Insulin Resistance (HOMA-IR) with therapeutic CPAP vs. Sham CPAP
Mean and Standard Deviation of Insulin Sensitivity Index (ISI(0,120)) With Therapeutic CPAP vs. Sham	20 Weeks	Insulin Sensitivity Index derived from the Gutt Index, uses the plasma glucose and insulin concentration from fasting (0 min) and 120-min samples from the OGTT, to calculate (Metabolic Clearance Rate)/log (Mean Serum Insulin). The range of possible values is based on the subset ranges of fasting and oral glucose tolerance test (OGTT) insulin and fasting and OGTT glucose, which calculate to be a range of 1.6 to 206.8. An increase in the ISI (0,120) indicates an improvement in the insulin sensitivity.
Mean and Standard Deviation of Glucose Indices After Therapeutic CPAP vs. Sham	20 weeks	Reported values include: fasting glucose (mg/dL), 2 hour Oral Glucose Tolerance Test (OGTT) (mg/dL)