Autonomic Nervous System Function Following Bariatric Surgery

Autonomic Nervous System Function and Novel Determinants of Glucose Homeostasis Following Bariatric Surgery

In the proposed study, the investigators will explore three specific aims. First, the investigators will examine cross-sectionally the association of obesity on sympathetic, parasympathetic, and sympathetic/ parasympathetic nerve fiber balance. In addition, the investigators will determine the relationship of the ANS and osteocalcin. Osteocalcin will be measured before and after a mixed meal tolerance test.

In the second specific aim, the investigators will prospectively follow-up these individuals (n=30) following bariatric surgery. The effect of weight loss on measures of the ANS and osteocalcin will be examined 6 months following surgery with participants serving as their own control, pre- and post-surgical intervention.

Thirdly, the investigators will address whether the effect of weight loss on the ANS and osteocalcin differ between those who had a history of diabetes at baseline versus those with no history of diabetes.

Inclusion Criteria:

1. Individuals aged 18 - 60 years old.
2. Individuals with a BMI > 35 kg/m2.
3. Patients that have enrolled in a program to undergo weight loss by Roux-en-Y gastric bypass and having passed the pre-operative clearance program.
4. Individuals with diabetes who are currently being treated with diet, exercise, and/or oral medications will be included.

Exclusion Criteria:

1. Patients that have had previous gastric surgery, including but not limited to pancreobiliary diversion, vertical banded gastroplasty, and jejunoileostomy.
2. Individuals with known coronary artery disease (e.g., post-MI), atrial fibrillation,frequent atrial arrhythmias, frequent ventricular arrhythmias, a pacemaker, or myocardial ischemia.
3. Individuals taking the following medications that may affect the autonomic nervous system: anti- tuberculosis drugs, nitrofurantoin, metronidazole, chloramphenicol,perhexiline maleate, amiodarone, clofibrate, tricyclic antidepressants, phenytoin,methotrexate, barbiturates, neuroleptic drugs, antiparkinsonism drugs, fluoxetine, and nitrated drugs.