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

Not Applicable

Completed

Brief Summary: 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: 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.

Recruitment & Eligibility

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Arm && Interventions

Group	Intervention	Description
Moderate Hypoxia	Hypoxico Altitude Training Systems	2-weeks of nightly exposure (7-12 hrs per night) to moderate hypoxia (\~2,400 meters) using the Hypoxico Altitude Training Systems device.

Primary Outcome Measures

Name	Time	Method
Insulin Sensitivity	Baseline and Post-Moderate Hypoxia (14 days)	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.

Secondary Outcome Measures

Name	Time	Method
Insulin Secretion	Baseline and Post-Moderate Hypoxia (14 days)	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.
Beta-cell Function	Baseline and Post-Moderate Hypoxia (14 days)	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).
2-hour Glucose Area-under-the-curve	0, 0.5, 1, 1.5, and 2 hours at Baseline and Post-Moderate Hypoxia (14 days)	2-hour glucose area-under-the-curve (mg/dL x hour) was determined using an oral glucose tolerance test.
2-hour Insulin Area-under-the-curve Via 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 (μU/mL x hr) was determined using an oral glucose tolerance test.