Effect of 2-Week Nightly Moderate Hypoxia on Glucose Tolerance in Individuals With Type 2 Diabetes

Study Overview
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Brief Summary
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The purpose of this study is to determine if 2 weeks of nightly exposure (7-12 hours per night) to moderate hypoxia ( 2,400 meters or 7,500 feet) improves glucose metabolism in people with type 2 diabetes.

Detailed Description
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Exposure to hypoxia has been advocated as a possible therapeutic aid against obesity. Indeed, our laboratory has provided the first evidence that intermittent, nightly exposure to moderate hypoxia is beneficial in improving insulin sensitivity in healthy obese patients and, therefore, lowers the risk of developing type 2 diabetes. Benefits included reduced fasting glucose levels and improved whole-body (skeletal muscle) and hepatic insulin sensitivity. Whether such intermittent hypoxia improves glucose metabolism in people with type 2 diabetes is unknown.

Official Title
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Effect of 2-Week Nightly Moderate Hypoxia on Oral Glucose Tolerance in Individuals With Type 2 Diabetes

Conditions
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Type 2 Diabetes

Intervention / Treatment
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* Device: Hypoxico Altitude Training Systems


Participation Criteria
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Eligibility Criteria
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INCLUSION CRITERIA: Aged 20-65 yrs Body mass index (BMI) < 55 kg/m2 Body weight 450 lbs or less (to accommodate body composition assessment) Have either been diagnosed with type 2 diabetes, or fasting blood glucose between 125 and 200 mg/dL, or have a hemoglobin A1c ≥ 6.5% Non-smokers Weight stable over the previous 3 months (<3 kg fluctuation) Known diagnosis of sleep apnea and ownership of a continuous positive airway pressure (C-PAP) device that must be worn throughout the nights spent in the tent If no known presence of sleep apnea, be willing to spend one night in a sleep laboratory (Louisiana Sleep Foundation) to assess presence of sleep apnea EXCLUSION CRITERIA: Diagnosed with T2DM ≥ 15 years ago Pregnant Women Current insulin treatment Treatment with sulfonylureas or glitinides Treatment with a GLP-1 agonist Any other diabetes medication other than an oral agent is exclusionary unless otherwise cleared by medical investigator. Chronic Obstructive Pulmonary Disease (COPD) Congestive heart failure Prior severe cardiovascular events such as stroke or myocardial infarction If treated for T2DM with other oral agent, no change in the treatment for 1 month before the study and the duration of the study Previously known diagnosis of sleep apnea without ownership of a continuous positive airway pressure (C-PAP) device or agreement to use owned CPAP device during the nights spent in the tent Presence of sleep apnea following a positive home sleep test (HST), or have unsafe oxyhemoglobin saturation levels (less than 78%) during a one night sleep monitoring assessment conducted at the Louisiana Sleep Foundation without ownership of a continuous positive airway pressure (C-PAP) device or agreement to use owned C-PAP device during the nights spent in the tent History of high altitude sickness History of altitude sickness Does not have access to a bed or sleeping surface equivalent to or smaller than a queen size mattress

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Moderate Hypoxia<br>2-weeks of nightly exposure (7-12 hrs per night) to moderate hypoxia ( 2,400 meters) using the Hypoxico Altitude Training Systems device. | Device: Hypoxico Altitude Training Systems<br>* Participants will sleep in a tent (which will fit his/her personal mattress) simulating an altitude of  2,400 meters for 7-12 hours each night for a period of 14 days. Baseline testing measures will include a oral glucose tolerance test (OGTT) and body composition (iDXA). Post-treatment testing measures will include OGTT only.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Insulin Sensitivity | Insulin sensitivity was determined using an oral glucose tolerance test. Insulin sensitivity was estimated using the whole-body insulin sensitivity index (WBISI), also known as the Matsuda Index (unitless): WBISI = 10,000 / [square root of (Glu0 x Ins0) x (mean glucose x mean insulin during an oral glucose tolerance test)] where Glu0 and Ins0 denote baseline glucose and insulin concentrations. | Baseline and Post-Moderate Hypoxia (14 days) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Insulin Secretion | Insulin secretion was determined using an oral glucose tolerance test. Insulin secretion was estimated using the Insulinogenic Index (IGI), an index of first-phase insulin response, and calculated from the ratio of the increments of serum insulin to glucose measured at 30 minutes: IGI (unitless) = (Ins30 - Ins0)/(Glu30 - Glu0), where insulin and glucose from 0 and 30 minutes are used. | Baseline and Post-Moderate Hypoxia (14 days) | 
| Beta-cell Function | Beta-cell function was determined using an oral glucose tolerance test. Beta-cell function was estimated by the Disposition Index, or the product of insulin sensitivity and insulin secretion: DI (unitless) = Matsuda Index (WBISI) x Insulinogenic Index (IGI). | Baseline and Post-Moderate Hypoxia (14 days) | 
| 2-hour Glucose Area-under-the-curve | 2-hour glucose area-under-the-curve (mg/dL x hour) was determined using an oral glucose tolerance test. | 0, 0.5, 1, 1.5, and 2 hours at Baseline and Post-Moderate Hypoxia (14 days) | 
| 2-hour Insulin Area-under-the-curve Via Oral Glucose Tolerance Test | 2-hour insulin area-under-the-curve (μU/mL x hr) was determined using an oral glucose tolerance test. | 0, 0.5, 1, 1.5, and 2 hours at Baseline and Post-Moderate Hypoxia (14 days) |