This is a descriptive, observational, longitudinal trial where the metabolism of the Roux limb of the small intestine will be analyzed in patients who have had Roux-in-Y Gastric Bypass surgery (RYGB). This analysis will include the time course of its adaptive changes in patients with Class II and Class III obesity, who have eight Type 2 diabetes (T2DM) or people who do not (study groups). It is hypothesized that intestinal remodeling and metabolic reprogramming lead to increased metabolic activity and fuel utilization by the reconfigured intestine in humans and accounts, in large part, for the improvement in glucose homeostasis after RYGB in surgery in patient with T2DM.