CCK and diabetes mellitus: By contrast, when similar study was performed in those with type 2 DM and age- and BMI-matched controls who underwent RYGB, mucosal biopsies taken during surgery and enteroscopy done after 10 months after surgery showed that the density of cells that secrete GLP-1, CCK, and GIP increased after RYGB, which explains amelioration of diabetes and increase in insulin sensitivity after weight loss surgery (since GLP-1, CCK, and GIP have anti-inflammatory and insulin-sensitizing actions).