Bariatric surgery quickly improves tissue specific insulin sensitivity. Changes in glucose metabolism are seen within days after surgery, prior to any significant weight loss--raising the question of a difference between dietary restriction and early food intake after surgery. A major factor in the development of insulin resistance is obesity. It has been noted that by 3 months following Roux-en Y gastric bypass surgery in obese patients with (T2DM), fasting glucose and insulin levels are improved independent of weight loss, insulin resistance in muscle is lowered, and that the pro-inflammatory profile of resident microphages is lowered improving insulin sensitivity.