Effects of Treatment of Sleep Apnea on Metabolic Syndrome

Study Overview
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Brief Summary
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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
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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.

Official Title
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A Controlled Trial of Continuous Positive Airway Pressure (CPAP) Therapy on Metabolic Control in Individuals With Impaired Glucose Tolerance and Sleep Apnea

Conditions
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Impaired Glucose Tolerance, Obstructive Sleep Apnea

Intervention / Treatment
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* Device: Continuous Positive Airway Pressure (CPAP) (Philips-Respironics RemStar Pro® CPAP)
* Device: Sham-Continuous Positive Airway Pressure (CPAP) (Philips-Respironics)


Participation Criteria
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Eligibility Criteria
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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

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 75 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Continuous Positive Airway Pressure (CPAP)<br> | Device: Continuous Positive Airway Pressure (CPAP) (Philips-Respironics RemStar Pro® CPAP)<br>* Subjects will be randomized to 8 weeks of CPAP or sham-CPAP, followed by the alternate therapy after a one month wash-out.<br>* Other names: Philips-Respironics RemStar Pro® CPAP;|
| Sham Comparator: Sham-Continuous Positive Airway Pressure (CPAP)<br> | Device: Sham-Continuous Positive Airway Pressure (CPAP) (Philips-Respironics)<br>* Subjects will be randomized to 8 weeks of CPAP or sham-CPAP, followed by the alternate therapy after a one month wash-out.<br>* Other names: Philips-Respironics Sham CPAP;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of Subjects With Normalization of Impaired Glucose Tolerance (IGT) | 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) | 20 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mean and Standard Deviation of Glucose Indices After Therapeutic CPAP vs. Sham | Reported values include: fasting glucose (mg/dL), 2 hour Oral Glucose Tolerance Test (OGTT) (mg/dL) | 20 weeks | 
| Mean and Standard Deviation of Insulin Indices After Therapeutic CPAP vs. Sham | The data for fasting and 2 hour Insulin (iIU/dL) are presented according to therapeutic CPAP vs. Sham CPAP. | 20 weeks | 
| Mean and Standard Deviation of Indices of Insulin Resistance With Therapeutic CPAP vs. Sham | Homeostasis Model Assessment-Insulin Resistance (HOMA-IR) with therapeutic CPAP vs. Sham CPAP | 20 weeks | 
| Mean and Standard Deviation of Insulin Sensitivity Index (ISI(0,120)) With Therapeutic CPAP vs. Sham | 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. | 20 Weeks |