Assessment of Insulin Resistance, NAFLD, Predictors of CV Morbidity, and Subcutaneous Adipose and Visceral Adipose Gene Expression in Patients Undergoing Gastric Bypass Surgery
Condition: Morbid Obesity; Insulin Resistance; Non-Alcoholic Fatty Liver Disease
MeSH terms: Liver Diseases; Fatty Liver; Non-alcoholic Fatty Liver Disease; Obesity; Insulin Resistance; Obesity, Morbid
Study type: Observational

Summary: 
      The purpose of this research is to further study the effect weight loss after gastric bypass
      surgery has on the heart and blood pressure and on how the body uses or metabolizes the
      sugars, fats and proteins we eat. Additionally, the researchers want to study fat tissue for
      gene patterns which may be responsible for where we carry fat on our bodies, as well as look
      carefully at a possible link between adipose tissue and insulin resistance. The researchers
      also want to evaluate the liver for the presence of fatty liver, which is common in people
      with obesity and is associated with insulin resistance, as well as study the liver for gene
      patterns which may be associated with non-alcoholic liver disease.

      Evaluating cardiovascular function and endocrine function before and after gastric bypass
      surgery, as well as studying adipose and liver tissue may help us understand the link between
      obesity, insulin resistance, fatty liver disease, high blood pressure and health problems
      such as diabetes and heart disease. Consequently, this may help in the future by identifying
      those who will benefit most from gastric bypass surgery.
    

Detailed description: 
      Obesity is associated with insulin resistance and diabetes. Since both of these conditions
      have been implicated in cardiovascular complications, this association may explain obesity
      related illnesses and deaths. Gastric bypass is considered the "gold standard" surgical
      weightloss procedure and has been demonstrated to cure diabetes and insulin resistance. Some
      severely obese patients, however, have normal insulin-glucose metabolism. The differences in
      metabolic healthy in severely obese individuals has not been fully recognized or understood.
      This research will study insulin-glucose metabolism in a population of severely obese
      individuals undergoing gastric bypass. This investigation is based on the following
      hypotheses:

        1. Severely obese individuals can be categorized by degree to which insulin-glucose
           homeostasis is impaired.

        2. The degree of insulin resistance correlates with risk for cardiovascular disease. Weight
           loss in obese individuals with insulin resistance, will correlate with improvement in
           parameters associated with cardiovascular disease. Obese individuals with better insulin
           sensitivity will not have a high risk for cardiovascular disease and therefore will not
           experience this risk reduction in cardiovascular disease.

        3. Insulin resistance is a consequence of pathological storage of excess energy intake;
           therefore, individuals who are insulin resistant and obese will differ from individuals
           who are obese, but not insulin resistant with regards to gene expression in subcutaneous
           adipose tissue and visceral adipose tissue.

      Subjects will be studied for evidence of end organ dysfunction and predictors of morbidity
      and mortality preoperatively and postoperatively. Additionally, gene expression in the
      subcutaneous and visceral adipose depots of subjects will be studied
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Severely obese patients undergoing gastric bypass surgery
      
Biospecimen description: 
      Subcutaneous and visceral adipose tissue.