The Effects of Normobaric Hypoxia on Blood Glucose Levels.

• Change in glucose levels at altitude [ Time Frame: 1 year ] [ Designated as safety issue: No ]
  Subjects will be placed on a Reduced Oxygen Breathing Device (ROBD2) to simulate 3 different altitudes at three separate and distinct time periods (ground, 8,000 feet and 12,000 feet) then obtain c-peptide and 2-hour OGTT to determine blood glucose changes during acute normobaric hypoxia.
  
  

A total of 25 subjects (MOFH personnel and DoD beneficiaries) will be recruited from all male and female subjects whom are at least 18 years of age at the MOFH. All patients who meet the inclusion criteria will be offered the opportunity to participate by the PI, AI or study staff. We will recruit patients using the attached Recruitment Flyer and Advertisement in the Nellis Air Force Base newspaper. All subjects will have at least a one week break in between each visit and will be told to fast (not eat or drink anything) for at least 8 hours prior to Visits 1, 2 and 3.. If during the baseline (ground) test any of the 20 non-diabetic patients are found to be a diabetic, they will be notified and the attached form letter will be sent to their Primary Care Manager (PCM) alerting them to this finding so that they may begin treatment. Visit 1, our baseline testing at room air (22% oxygen), is being used as our control. If the patient exhibits hyperventilation secondary to claustrophobia, the Principal Investigator or Associate Investigator may disenroll the patient from the study. No procedures on this research protocol are part of standard of care. They are all done for research purposes only

Screening Visit:

• The subjects' medical history will be reviewed. Informed Consent and HIPAA Authorization will be obtained. Females of child bearing potential will then be sent to the laboratory for a pregnancy test (5-10 milliliters (mls), approximately 1-2 teaspoons of blood). Schedule patients for Visit 1. Patients will be told to fast for at least 8 hours prior to Visit 1.

Visit 1 (within 1 week of screening visit):

• Subjects will have an intravenous line (IV) inserted in their arm. The subjects will then be placed on the ROBD2 at room air (22% oxygen) for 2.5 hours. During the altitude simulation, the subjects will drink a sugar mixture containing 75 grams of sugar for a 2-hour OGTT (glucose levels drawn at 0, 60, 120 minutes) (5-10 milliliters (mls), approximately 1-2 teaspoons per blood draw), c-peptide tests (drawn at 0, 60, 120 minutes) (5-10 milliliters (mls), approximately 1-2 teaspoons per blood draw), and will also be asked to complete the AMS questionnaire (see attached) at 0, 60 and 120 minutes to determine if they are experiencing any adverse effects of hypoxia. Patients will be told to fast for at least 8 hours prior to Visit 2.

Visit 2 (at least 1 week after Visit 1):

• The subject will have an intravenous line (IV) inserted in their arm. The subjects will then be placed on the ROBD2 to produce altitude simulation at 8,000 feet (15.6% oxygen) for 2.5 hours. During the altitude simulation, the subjects will have a 2-hour OGTT (glucose levels drawn at 0, 60, 120 minutes) (5-10 milliliters (mls), approximately 1-2 teaspoons per blood draw), c-peptide tests (drawn at 0, 60, 120 minutes) (5-10 milliliters (mls), approximately 1-2 teaspoons per blood draw), and will also be asked to complete the AMS questionnaire (see attached) at 0, 60 and 120 minutes to determine if they are experiencing any adverse effects of hypoxia. Patients will be told to fast for at least 8 hours prior to Visit 3.

Visit 3 (at least 1 week after Visit 2):

• The subject will have an intravenous line (IV) inserted in their arm. The subjects will then be placed on the ROBD2 to produce altitude simulation at 12,000 feet (13.4% oxygen) for 2.5 hours. During the altitude simulation, the subjects will have a 2-hour OGTT (glucose levels drawn at 0, 60, 120 minutes) (5-10 milliliters (mls), approximately 1-2 teaspoons per blood draw), c-peptide tests (drawn at 0, 60, 120 minutes) (5-10 milliliters (mls), approximately 1-2 teaspoons per blood draw), and will also be asked to complete the AMS questionnaire (see attached) at 0, 60 and 120 minutes to determine if they are experiencing any adverse effects of hypoxia.

Subject's participation in this study will last approximately 3 weeks and is completed after Visit 3.

If at any time during the study, the subject is found to be diabetic, they will be notified and referred to their Primary Care Manager (PCM) to initiate standard of care treatment. If a subject becomes pregnant during the study, they will be withdrawn from the study and referred to their PCM for standard of care treatment. If patients are withdrawn from the study, no further testing is required.

Patients must agree to take precautions to prevent pregnancy during the course of this study due to the possible effects the simulation of altitude may have on an unborn child. The only completely reliable methods of birth control are total abstinence or surgical removal of the uterus. Other methods, such as the use of condoms, a diaphragm or cervical cap, birth control pills, IUD, or sperm killing products are not totally effective in preventing pregnancy. Also, women who are breastfeeding may not participate in this study.

2-hour OGTT tests are performed to see how quickly glucose is metabolized from the bloodstream for use by cells as an energy source. This test requires a patient to fast. Blood is drawn to establish a fasting glucose level. Next, a patient must drink a sugary beverage (containing a 75 gram glucose load), then blood is drawn again at 60 minutes and 120 minutes after the beverage is consumed.

If during altitude, glucose is elevated, patients will not be removed from the study.