Relationship Between Changes in Gut Hormones After Gastric Bypass and Gastric Banding and Improvements in Diabetes

Inclusion Criteria: * Male and female participants age 18 years or older with a body mass index greater than \>35 kg/m2 but less than \<60 kg/m2 who undergo gastric bypass or gastric banding at the University of Pennsylvania. * Type 2 diabetes (defined as a pre-existing diagnosis, the use of oral antidiabetic medications or insulin, or a fasting plasma glucose greater than or equal to \> 126 mg/dl and confirmed by a oral glucose tolerance test) * Ability to provide written informed consent Exclusion Criteria: * A diagnosis of type 1 diabetes * Daily insulin requirement exceeding 1 unit/kg/d * Poor preoperative glycemic control, as indicated by an HbA1c greater than 10.0% * Duration of diabetes greater than\> 10 years * Pregnant women (or those who intend to become pregnant during the study period) * Women who are currently breastfeeding * Participants with moderate anemia (hemoglobin less than\< 12 g/dl for men and less than\< 11 g/dl for women) * Use of medications known to affect weight, including chronic oral or inhaled glucocorticoid use and the use of certain psychiatric medications (olanzepine, risperidone, and lithium) * history of any major active rheumatologic, pulmonary, dermatologic disease, or inflammatory conditions * oral history of positive HIV status * any major surgery in the past 3 months * regular use of alcoholic beverages (greater than 7 drinks/week) * prior reaction to human albumin